How to cut rigid foam insulation

When Chris Ellis of Brewster, Mass., was looking for the right tool to cut rigid-foam insulation, he tried a utility knife, a kitchen knife, and a saw. None of those options worked especially well. So Chris created something that works beautifully. As Chuck Miller demonstrates in this video tip, a 2-in. putty knife with a sharpened blade cuts through the foam like butter.

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After watching this vid a little while ago I used the sharpened putty knife to do my basement in November going through a few dozen 2″ sheets of extruded foam and the approach works very well. I’d cut on the concrete floor using a thin piece of plywood as the straight edge. I was surprised to find such a clear “grain” in the foam; it can be sliced up very easily length-wise but across the foam it’s always trickier.

Anyway, the sharper the knife the better. I used a cheap harbor freight cutoff wheel tool to grind down one edge into a pretty sharp blade. Also, to avoid ripping the top when cutting across, score a thin trench first, then deeper on each pass.

I cut several sheets with a circular saw before this and the sharp putty knife is cleaner (no dust), quieter, and much faster, not to mention more accurate, too. I cannot imagine a better way to do it, thanks!

In the art world, foam board insulation is used as a flexible backing for decorations and mosaics. Foam board insulation is perfect for insulating a small area while reducing humidity and dampness.

You can generally use a utility knife when there are slighter cutting requirements of foam board insulation. If you need several cuts, you can use a circular, jigsaw, or table saw to save time and effort.

By cutting foam board insulation carefully and with the right tools, you can make a perfect artery in rigid insulation foam.

If a utility knife is the best tool for cutting thin boards, a saw is the best tool for cutting foam board insulation. You can use a circular saw blade or a grinder for cutting rigid board insulation to ensure smooth and firmly cutting. In this context, I will give you proper guidelines about how to cut foam board insulation.

What Is Foam Board Insulation?

Rigid foam board insulation is excellent insulation, commonly found in tropical areas, especially in hot regions. It is moisture-resistant and is easy to put in place. Rigid sheets of polystyrene, polyisocyanurate, or polyurethane insulation make up foam board insulation.

You can use foam board insulation to insulate every exposed cavity in your home from top to bottom, including walls. You can also use it while remodeling and the drywall are down. It’s even possible to mount it in your pole barn’s open cavities.
Foam board insulation has a high thermal resistance and minimizes heat transfer by structural elements like wood and steel studs.

What Is Best Tool for Cutting Foam Insulation Board?

  • Utility knife
  • Worktable
  • Felt-tip marker
  • Circular saw
  • Jigsaw
  • Metal cutting or all-purpose jigsaw blade
  • Old steel circular saw blade
  • Vise
  • Grinder

Cutting Foam Board Insulation (Step by Step Guide)

Step-1: Preparation of the cut process

Place rigid foam on a flat surface to begin. If you hold the board flat while you work, it will be easier to cut precisely. If you don’t have a work table, find a flat and smooth surface to cut your foam insulation.

Ensure you have a protective shield in place, such as a knife barrier, when cutting rigid foam insulation on decorative tables. You could scratch the table if you do this. You can use straps to adhere all sides of the insulation to the work surface. To make a perfect artery, align the string line with the cutting line.

Step-2: Measure your cut

Measure the length and width of the rigid foam you’ll need for a particular project before you cut it. To make sure your rigid foam insulation is long and wide enough, compare these measurements to the length and width that it currently has. Check the length and width of the item 2-3 times to ensure accuracy.

Step-3: Mark your cutting line

For doing this, you need to draw a cutting line on the foam. You can then take a straightedge ruler on the rigid foam to make the sign you can follow for cutting the foam. Draw a line down the side of your straightedge with your pencil. Then double-check the marking to ensure it’s accurate.

The straightedge should be installed across the cutting line to help you make a perfect alignment. This will prevent the rigid foam insulation from dropping or collapsing when being cut.

Step-4: Choose 1 of 6 Different Cutting Method

Method-1: Cut Thin Sheets with Utility Knife

To do so, use a segmented blade to cut your insulated foam. You should use this type of utility knife because they are more efficient than other options at cutting rigid insulation foam. You can buy them on the internet or in most hardware stores. Now, you may follow these steps.

Rigid foam insulation board claims to be easy to cut. It says right on the board, usually. But when someone saw me doing that in the Home Depot parking lot, he said, “You’re a braver soul than me!” But if you know my trick, it’s not hard. Here’s how to cut rigid foam insulation board, with simple hand tools, and minimal mess. The best way to cut foam board even allows you to cut it right in the Home Depot parking lot, so the board will fit in a small SUV.

Thin foam board will cut with just a utility knife, but you can easily cut the thicker 2-inch boards, even with just simple tools.

Using a drywall saw

How to cut rigid foam insulation

Rigid foam insulation board cuts easily with a drywall saw but it makes a mess. The best way is even easier, with little to no mess.

If worse comes to worse, you can cut rigid foam insulation board with a drywall saw. It cuts really easily. And if you have to cut a small amount, say, less than a couple of inches, this probably is the easiest way. Draw your line, stand the board up, then saw along the line as close as possible.

It’s not especially hard, but it can take a few minutes, especially if you have to cut the full length of an 8-foot sheet. And I don’t like the mess. The polystyrene shavings attract static electricity so it really likes to stick to the broom or vacuum cleaner.

And if you need to make a small cutout, this is probably the best way to do it. The 2×3 cuts to accommodate an electrical box come to mind. You might be able to minimize the mess by cutting with a utility knife first, then finishing the cut with the saw.

So I prefer another method that’s much faster, more precise, and makes less mess.

Best way to cut rigid foam insulation

The best way to cut rigid foam insulation requires very simple tools:

  • A board, 6-8 feet long (I prefer a 1×4, but a 2×4 will work)
  • Knee pads (optional but recommended)
  • A utility knife
  • A permanent marker
  • A tape measure

Sometimes the knife, marker, and tape measure are optional, especially in the parking lot.

You can get the board at the store too. Be sure to check the cull lumber section. Cull lumber is my very favorite DIY trick.

Using the factory spacing to get perfect 16-inch widths

How to cut rigid foam insulation

By placing a 1×4 over a shallow cut, either made from the factory or one you cut yourself with a utility knife, rigid foam board snaps easily.

If you look closely at the foam board, at least the thicker ones, there are slight grooves cut into it at 16-inch intervals. If you placed your studs exactly 16 inches apart, you can use these to break your board into perfect 16-inch widths. If you haven’t framed your studs yet, use one of these as a spacer when you do, to make your life easier.

To break the board into perfect 16-inch widths, just place your 1×4 board right along one of the grooves. Stand on the board, or kneel on the board if you have knee pads, kneel on it. Then reach down and pull the board up toward you. It snaps along the line surprisingly easily. You can do it yourself in the parking lot of the store, just park in the back, where you’re likely to have a bit of room. I like to use the adjacent parking spot, if I can find a lonely enough section of the lot.

And hey, someone who sees you doing it might even be impressed with your bravery, or skill.

Cutting rigid foam insulation board to custom lengths or widths

Frequently you’ll need custom lengths or widths of foam board, so that’s where the tape measure, marker, and knife come in. Measure the dimensions you want, then mark them with the marker. Cut along the line with your knife. Repeat on the other side for the cleanest possible cut. You can skip this step, but you risk a jagged break.

How to cut rigid foam insulation

Then place your 1×4 board along the cut, and stand or kneel on it, and pull the board up toward you. It will snap. You’ll get a clean, smooth edge with little to no mess.

How to cut rigid foam insulation

Cutting thin rigid foam insulation board

Rigid foam insulation board comes in various thicknesses. The half-inch or inch-thick boards can simply cut with a utility knife, if you want. I generally find it easier to make a shallow cut and snap it like I would 2-inch board anyway, but try whichever way you find works best for you.

In respect to this, how do you cut insulation in pink foam board?

You can either use a special scoring tool, or just make cuts with the utility knife. A score will not penetrate through the board all the way. Bring the foam board up on it’s edge and snap against the score line. The board should easily break apart at the score marks.

  1. Use a segmented blade to cut your insulated foam. Segmented knives have ridges running along the bottom of the blade.
  2. Score the insulated foam with your utility knife.
  3. Make a second cut to finish the incision.
  4. Remove the clamps and examine the foam piece.

Also, how do you cut foil face foam insulation?

Lay the foam board on a flat work surface. If only one side is foilfaced, lay it foil-side up. Use a measuring tape to find the place you want to cut, and place a straightedge along the line to guide you. Draw the line in marker for extra cutting assurance if desired.

Can I cut foam with a jigsaw?

If you do it wrong, cutting through foam can be a spectacularly messy job. Before attempting to cut the foam take a well-used jigsaw blade and, holding it with a pair of locking pliers, grind off the the teeth and create a smooth knife edge. Your jigsaw will give you a nice, clean cut through foam every time.

How to cut rigid foam insulation

Foam board insulation is a relatively inexpensive type of insulation that adds a high R-Value to areas where adding standard installation is either cost-prohibitive or not required. Foam board insulation is often used in garages, work sheds, or other spaces that may not require interior finish or wall trim.

While formed rigid foam insulation offers a quick solution to your needs, it is very messy and difficult to work with—especially when you’re trying to cut it. Follow these steps for a better result and an easier cleanup.

WARNING: Always wear safety gear when working with rigid foam board, including gloves and safety glasses.

Step 1 – Measure and Mark

Measure the distance on the foam board insulation that you wish to cut, and then make a mark there. This will serve as your cutting line. Always remember and follow the adage “measure twice, cut once” so you don’t get the wrong sized pieces and end up wasting material.

Step 2 – Prepare to Cut

Next, take your long straightedge and line it up with your cutting lines. Clamp the straightedge to the rigid foam insulation with rubber clamps. Make sure they are securely and firmly in place so that the pieces will not shift or slip during the cutting.

Step 3 – Cut the Foam Insulation Board

With your utility knife, score the foam insulation board by firmly running the utility knife along the outer edge of your straightedge. This will result in a small impression or etching in the board.

While cutting, make sure that your knife cuts to the outside edge, or “waste area,” of the board. That way, if you make a mistake, it will not damage or destroy the entire piece.

Once you finish the scoring the board with your utility knife, remove the clamps and straightedge.

Step 4 – Complete the Cut

Lift the foam insulation board so that the sheet is sitting upright. Then, snap along the scored cut by pressing hard against the backside of the score (etching) line while securely holding the side edges of the board. If you have properly scored the foam board, it should simply pop or snap off. Remember to snap the foam board from the uncut side of the insulation board or it make not work as you want it to.

Continue this method for all the pieces you need cut for your insulation project. This procedure should produce precise, clean cuts and less waste in the end. However, keep in mind that this method may be hard to use without help for particularly large sheets of rigid foam insulation, so adjust as needed.

Can you cut insulation board with a table saw? You can generally use a utility knife when there are slighter cutting requirements of foam board insulation. If you need several cuts, you can use a circular, jigsaw, or table saw to save time and effort.

What is the best way to cut polystyrene insulation? Use a putty knife to cut the foam.

If you don’t have a utility knife, a putty knife can work as an alternative. Sharpen the putty knife to give it a pointed edge, then use it in place of your utility knife as you cut through the foam.

How do you smooth edges of foam board? For example, a pair of kitchen scissors will cut through it if you don’t care about the edges, and even a hand saw can do the work if the board is too large for scissors to handle. Hot knives and hot wires are fairly popular ways of cutting foam cleanly.

How do you cut rigid foam insulation? – Related Questions

Can I use a jigsaw to cut foam?

The S 155/W jigsaw blade is engineered to cut rigid foam and fiberglass insulation, cardboard, foam rubber, and similar materials up to 5 inches. Festool jigsaw blades are engineered for cutting efficiency, long life, and superior cutting results, with a universal T-shank design that fits most professional jigsaws.

Can you cut insulation with a jigsaw?

A standard-length jigsaw blade won’t cut all the way through the 2″ foam board so you can cut even thin materials. The insulation board will last a long time before it needs replacing.

Is polystyrene insulation any good?

How effective is polystyrene insulation? Polystyrene is a great thermal insulator, and can achieve excellent R value ratings at a given thickness for EPS, and even higher ratings for XPS. XPS polystyrene foam is more effective due to its dense structure and excellent moisture resistance.

What is the best tool to cut Styrofoam?

Use an electric kitchen knife, such as a carving knife or a fish fillet knife, to create clean cuts in Styrofoam. Place the electric knife on the foam along the desired cutting line. Do not exert pressure on the electric knife, but allow the serrated blades to gently cut through the Styrofoam.

Is cutting Styrofoam toxic?

Once the foam is cut, the heat can cause the blocks to off-gas volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, xylene (BTEX) and styrene into the air.

How do you cut 2 inches of Styrofoam?

Cutting Rigid Foam With a Circular Saw

When you’re insulating a building, you have to cut a lot of sheets, and if you’re using 2-inch foam for maximum insulating value, the easiest way to cut them is to use a saw. A circular saw will cut through 2-inch foam sheets like butter.

Can you sand foam board?

These foams are very easy to cut with a knife (or hot wire cutter, except PU foam) and both styrofoam and PU foam can be sanded effortlessly to a smooth, sharp finish even for very small forms.

How do you clean foam board?

Foamboard is cleaned with a damp cloth or with isopropyl alcohol. Be careful with other cleaning agents, the top layer is thin and by rubbing or pressing too hard, the foam core will become visible!

What is the best tool to cut plywood?

Most projects that involve plywood require cutting to size. Many homeowners wonder what the best way to cut plywood is. You can cut plywood with a handsaw, jigsaw, table saw or circular saw.

How do you secure wood for cutting?

Woodworkers use C-clamps to hold pieces of wood to the workbench or to each other and bar clamps to hold wider pieces. Vises work by the same principle, but they are fixed to the workbench. Clamps and vises with wooden jaws, unlike those with metal jaws, can hold wood securely without damaging it.

Can I use a jigsaw to cut plywood?

The jigsaw can be used to make both straight and curved cuts in a wide variety of materials, including wood, particleboard, plywood, plastic, metal, even ceramic tile.

Is kingspan better than polystyrene?

Celotex, Kingspan etc will have a higher U value than normal polystyrene so you would have to increase the thickness of the poly to achieve what Celotex would give you. Also, Celotex etc. is denser than poly and for a floor, you need something firm.

Can you use polystyrene sheets as insulation?

EPS (Expanded Polystyrene)

This is what makes it a great insulator. Because it’s so lightweight, EPS is perfectly safe to fix to the walls using our dual-fixing method of adhesive and mechanical fixings.

Is polystyrene insulation a fire hazard?

Like practically all organic building materials polystyrene foam is combustible. However in practice its burning behaviour depends on the conditions under which it is used, as well as the inherent properties of the material. When installed correctly, expanded polystyrene products do not present an undue fire hazard.

Can you cut foam with a Dremel?

We suggest using any of the following to cut your foam: Dremel tool: use a straight grout bit with knurled teeth; to smooth contours, select a ½” or ¼” sanding drum. Rotary cutter or router: set to desired depth. X-Acto Knife: Model # X7747 is for foam cutting and can be purchased online or at art supply stores.

How does Styrofoam shape with heat?

Utilize a hot wire cutter for smooth cuts.

Hot wire cutters melt through the foam with a heated wire, creating a smooth edge. They are especially effective for creating rounded edges or shapes out of styrofoam. Apply slow, consistent pressure with the hot wire cutter along the desired cutting line.

What paint does not eat Styrofoam?

You can also use acrylic paint or latex paint to paint Styrofoam, as they will not damage the Styrofoam. Avoid using chemical- or solvent-based paints, as they will damage or eat the Styrofoam away.

Can you waterproof polystyrene?

For that reason, although polystyrene is a waterproof plastic, styrofoam isn’t entirely waterproof or moisture resistant. This is done by waterproofing the styrofoam using spray-on coating or plastic sheeting, but more on that later.

Is Breathing in Styrofoam bad?

Symptoms for short-term exposure include mild coughing or irritation of the eyes or throat. Long-term exposure has shown a higher occurrence of lung issues like bronchitis, scarring, chronic cough or reduction in lung function. The dust is so fine, it is easily inhaled and causes respiratory issues.

Is it bad to inhale Styrofoam dust?

The primary adverse health effects of this material are related to the dust created by sanding, grinding or cutting the cured foam. Inhalation: May irritate mucous membranes with tightness in chest (This only if dust is created during cutting, sanding or grinding of cured foam).

We are proud to offer a versatile range of rigid foam insulation boards with superior thermal resistance for building and construction industries.

Features of our various foam insulation boards include moisture resistance, high compressive strength, long term stability, light weight for ease of handling, and dust-free when trimming and cutting. Foam insulation boards are considered environmentally friendly and efficient, and are a value-for-money choice where rigid board insulation is required.

Brief product descriptions for each of our main categories of foam insulation board can be found at their respective links below. More detailed product data and product test results can be found under Data Sheets.

Foam Insulation Boards – The Range

  • Polystyrene (EPS) – Expanded polystyrene is our most popular rigid foam product, used throughout the building and construction industry, for block-outs and void fillers as well as for thermal insulation.
  • Saviro XPS Blue Board– Extruded polystyrene (XPS), often referred to as ‘Styrofoam’ or ‘Blue Board’ is the superior polystyrene for under concrete slabs, heated floors, rooftop thermal insulation, and for any environment requiring resistance to moisture.
  • Rigid Polyurethane (PUR)– an old favourite in composite building panels and for under slab insulation

We carry large stocks of the Polystyrene product ranges in our Perth warehouse for immediate commercial and retail requirements. For other industrial foam ranges check out our Trade Desk.

For Product Data and Technical Information on all Foam Sales’ Rigid Foam Insulation ranges see our Resources Pages .

Rigid foam board insulation provides a high insulating value and is ideal for both interior and exterior applications. Typically made of polystyrene, polyisocyanurate or polyurethane, rigid foam board insulation can be used in both new and retrofit construction. Whether you’re constructing a new office building, building a new home or doing a major energy efficiency upgrade, Liberty Insulation is here to help.

As with many types of insulation, installation is a key factor in ensuring it functions at its highest capacity. That’s why you should call on the experts at Liberty Insulation in York, PA. We will help you determine whether rigid foam board insulation is the right fit for your project, and we’ll make sure it’s installed to our high standards, keeping your home or business insulated from the elements.

Benefits of Rigid Foam Insulation

Rigid foam board insulation has a high insulating value relative to its thickness, providing optimal insulation for small spaces like framed walls. Rigid foam board insulation can be used in:

  • Masonry cavity walls
  • Below-grade basement walls
  • Crawl spaces
  • Framed walls (wood and metal)
  • Pre-engineered metal buildings
  • Cathedral and flat ceilings

While other types of insulation may not provide enough insulation per square inch in small spaces, rigid foam board insulation doesn’t need as much space to increase energy efficiency. Fully insulating small spaces with rigid foam boards can help increase the energy efficiency of your home or business and cut down on your energy bills.

Types of Rigid Foam Insulation

Rigid foam board insulation typically comes in three products:

  • Expanded Polystyrene Foam is typically used for insulated concrete forms or for roof and wall panel insulation on commercial buildings. Made from foam similar to foam packing material, expanded polystyrene foam is the least expensive of the options but also has a lower insulation capacity per inch.
  • Extruded Polystyrene Foam is widely used in home insulation and provides stable, high quality thermal performance over time. Sometimes referred to as blue board or pink board, extruded polystyrene foam is often used to insulate basements.
  • Polyurethane or Polyisocyanurate Foam is the most expensive rigid foam insulation product, but it also comes with the highest insulation capacity. Reflective foil facing on polyisocyanurate adds to its thermal capacity when used in buildings with radiant heat.

Our expert insulation team will explain the benefits of each type of foam board and help determine which is right for your project.

York’s Expert Insulation Installers

At Liberty Insulation we pride ourselves on decades of experience in insulation services, working with customers to determine the right type of insulation for the project, and providing expert installation. Serving the Pennsylvania area since 1987, we have grown into Pennsylvania’s Largest Independent Insulation Contractor. Whether you’re building a new home, building a commercial project or upgrading the efficiency of your business, the experts at Liberty Insulation have you covered.

That is pretty cool. Its a nice idea. I don’t think I’d ever cut enough foam to make buying that tool worth while though.

When I cut a BUNCH of foam for my solar hot water lines between the house and the solar panel rack, I cut them with a pocket knife. It took a while, but it wasn’t messy and I cut it all inside my house.

How to cut rigid foam insulation

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To cut larger sections or swaths, I rig up a stationary vertical wire section to some jumper cables on the side of a bench.

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To cut larger sections or swaths, I rig up a stationary vertical wire section to some jumper cables on the side of a bench.

I’ve been using a small drywall keyhole type saw when cutting against the grain of 2" XPS but when I’m cutting with the grain I’d score each side with a box cutter and then snap it. The snap is clean but if I try to use the box cutter against the grain it breaks up the foam and doesn’t cut well so I use a keyhole saw for that.

I wish I knew the putty knife trick because that sounds slick. I ended up making a big mess in the basement when cutting my sill plate foam plugs but it wasn’t too big of a deal with a shop vac on a concrete floor.

On second thought I’m curious if buying one of the bigger style pizza cutters(large enough to go all the way through the foam you are cutting, not the tiny ones) and sharpening a good knife edge to it would be a good way to do this.

MN Renovator
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Wow, I used a circular saw. Made a fair mess and really gummed up the saw. That was a real pain to clean.

OTOH, It did a nice job. Since I was cutting WAY TO FAR from the sides or ends to use the yardsale flashlight model, it seemed like the thing to do at the time.

I’ve been using a small drywall keyhole type saw when cutting against the grain of 2" XPS but when I’m cutting with the grain I’d score each side with a box cutter and then snap it. The snap is clean but if I try to use the box cutter against the grain it breaks up the foam and doesn’t cut well so I use a keyhole saw for that.

I wish I knew the putty knife trick because that sounds slick. I ended up making a big mess in the basement when cutting my sill plate foam plugs but it wasn’t too big of a deal with a shop vac on a concrete floor.

On second thought I’m curious if buying one of the bigger style pizza cutters(large enough to go all the way through the foam you are cutting, not the tiny ones) and sharpening a good knife edge to it would be a good way to do this.

Yeah, just like a supermassive olfa tool. Just make sure to go fast enough and with lots of downward pressure.

How to cut rigid foam insulation

Foam cutting tools that are specifically designed to work with different types of foam can make working with foam easy. But if you’re working with any of these types of foam, the only tool you need may already be in your tool box:

  • Acoustic foam
  • Spray foam insulation
  • Rigid foam insulation
  • Foam pipe insulation
  • Foam underlayment
  • Foam board

There are professional foam cutting tools on the market, such as hot wire knives used by crafters and foam sculptors, table saws with cutout and ceramic-coated blades used to cut rigid foam insulation, and Dremel tools to carve intricate details. The vertical-bladed foam cutting saw is the professional’s tool of choice, but unless you’re cutting a lot of foam on a routine basis, it’s hard to justify the investment in one of these saws, which easily cost several hundred dollars.

There’s another option, one that’ll make economic sense for most users and their foam-cutting jobs: a utility knife. The only problem with this relates to the nature of foam. It’s either rigid and slick, thus making it likely that knife slips will occur, or soft and squishy, which causes jagged cutting if your knife’s the least bit dull. Repeatedly snagging and releasing the knife puts you at risk of accidental injury.

Even worse, cutting foam quickly dulls knife blades, so you’ll need a knife that has blades that are easily replaced. The nature of the material and the need for a strong, sharp knife to cut it has led people to use dangerous tools, like utility knives with traditional blades. Some have even tried butcher knives.

Slice ® industrial and utility knives are perfectly ground to a finger-friendly ® edge that is sharp enough to cut both soft and rigid foams, yet safe to touch during blade replacement.

Choosing the Best Foam Cutting Tools

So, what’s the best tool to cut foam? That depends on the type of foam you’re cutting. First, consider the composition and density of the foam. Generally, the denser the material, the thinner blade you'll want in order to reduce drag. To easily cut softer foam, you need a knife that is strong and unlikely to bend during cutting.

Foam Insulation Cutting Tools

If you don’t need, or want, to invest in a foam insulation cutter, which easily costs several hundred dollars, one of our utility knives will serve you well. Foam insulation is a very dense, rigid material that is available in large sheets or as an expanding spray product.

How to cut rigid foam insulation

Whether you’re cutting larger foam insulation sheets down to size or trimming overspray, you’ll need a thinner blade. Our 10490 Manual Metal-Handle Utility Knife or our 10491 Auto-Retractable Metal-Handle Utility Knife would work well in this application. We ship these knives with our rounded-tip blades as a safety measure, because the rounded tip reduces the likelihood of puncture injuries, but both of these handles are compatible with any of our Utility Blades, which include both a pointed-tip and serrated blade.

These knives also are excellent tools for cutting foam board (used to mount pictures) or foam underlayment (used to cushion hardwood floors). The 10490 Manual Metal-Handle Utility Knife is especially well-suited to these jobs, because the cutting depth of the blade can be adjusted to the depth of the foam board or underlayment. This reduces the risk of injury to yourself as well as damage to the material, since you won’t be exposing an excessive blade length.

Ceramic Utility Blades (Rounded Tip)

Manual Metal-Handle Utility Knife

Auto-Retractable Metal-Handle Utility Knife

Working With Softer Foams

Softer foams present a different set of cutting challenges. Whether you’re installing acoustic foam for insulation or soundproofing, protecting delicate electronic or photography equipment, or weatherproofing pipes with foam insulation, you need a tool that’s sharp, strong, and durable.

Soft foam tears easily, so you need a knife that’s sharp enough to slice right through it. In the case of thicker acoustic foam, you’ll also need a longer, stronger blade. Traditional blades are a bad option for cutting softer foams. Yes, they’re sharp. But that’s the problem. They’ll cut your skin just as easily as they cut the foam.

Slice’s finger-friendly safety blades are made from zirconium oxide, which is stronger than stainless steel. We use thicker blades and apply our proprietary grind, giving you a safe-to-touch blade that is less likely to bend, flex, or snap during cutting. You’ll get clean, straight cuts and your fingers will be safer.

Our 10559 Manual Industrial Knife and our 10560 Auto-Retractable Industrial Knife offer 76-millimeter (3-inch) blades that slice through soft, thick foams like butter. Here’s a video showing the 10559 in action cutting acoustic foam:

We ship both of our industrial knives with rounded-tip blades, as the rounded tip is less likely to cause an accidental puncture wound. Both handles are compatible with any of our Industrial Blades, which include both a pointed-tip and a serrated blade. With a simple blade reorientation, these knives can be reconfigured for right-handed or left-handed use.

A Final Word About PPE for Foam Cutting Safety

What’s the best way to cut foam? Safely, of course! That means wearing the appropriate personal protective equipment (PPE) before even attempting this job. If you’re working with rigid foam, cutting it can create flying bits and pieces, as well as dust. Wear protective goggles and a dust mask or respirator.

Protective gloves are always a good idea when working with knives. Choose gloves that give you the manual dexterity necessary to cut foam, yet protect your hands in case the knife slips.

By choosing Slice’s safer industrial and utility knives, with our finger-friendly blades, you are choosing safety and helping to protect yourself from lacerations. If you need foam cutting tools, Slice has you covered.

Maybe you could use an an old soldering iron to make something like this?


Well-known member
  • Dec 3, 2008
  • #3

For straight cuts just score with a utility knife and then snap it. For odd cuts around electrical boxes and such go down to you local hobby shop and buy a hot wire cutter. The one my son had looked like a coping saw with two d batteries. It cut it up like a hot butter knife through soft butter. Although it didn’t get that hot if I remember right.


Well-known member
  • Dec 3, 2008
  • #4

I use a table saw, cuts nice and straight and clean as possible. It does look like it snowed afterwards with all the foam dust, but you can’t beat the clean cuts.


Well-known member
  • Dec 3, 2008
  • #5


Well-known member
  • Dec 3, 2008
  • #6

Put the blade in your circular saw backwards.
It cuts real nice.


Well-known member
  • Dec 3, 2008
  • #7

Steve in Mi

Well-known member
  • Dec 3, 2008
  • #8

Depends on the type of foam somewhat. Dow rigid foam is easy to cut on a tablesaw but keep it down flat on the table as you run it thru and be awear that kickbacks can happen. I have run a few miles of it thru a bandsaw – that works well also if you happen to have a big enough bandsaw. You may experience some static shocks while sawing on foam – I mention it not because they will harm you but rather as a warning so that you don’t let it break your concentration to safety. Cutting out for electrical boxes in 1.5" will probably be easiest with a coarse tooth hacksaw blade, pointed some on the business end and wrap the other end with electrical or duct tape for a handle. Hand held drywall or keyhoe saw will work also. You can predrill two corners for the saw or work it back and forth starting nearly flat with the foam face and rocking it to a vertical position as you penetrate the backside. After a few of these you will be a PRO at it.

For slabing hot wire works okay on Dow polystyrene extruded foam. I have used a Variac, nichrome wire and a couple of electric fence insolators to slab a bunch of FREE 10′ X 12" X 24" billets into 1.5" sheets.

How to cut rigid foam insulation

As a leading insulation supplier in Melbourne , we are always developing new ways to provide the best product and service to people all over the city. Installing insulation in your home or business will bring many great benefits into your life, with the main one being increased thermal efficiency. Essentially, insulation acts to shield your home from external weather conditions and works to keep your home cool in summer, and warm in winter. This results in a reduction of how much artificial energy sources are utilised, creating lower utility bills and ultimately lowering your carbon footprint. If you are interested in installing rigid foam insulation , you have made a good choice. Here is a guide on how to do it yourself:

When installing rigid foam insulation, it is advisable to do so in unfinished walls. However, it can still be installed to masonry walls down the track. To install in an unfinished wall, begin by measuring the height and width of the wall cavities between the studs. Now, take your rigid foam insulation and cut it to fit these measurements. It is best to use a box cutter, table saw, or circular saw to save time when cutting and installing large quantities.

Next, press each sheet of insulation into the wall cavity, keeping it in place via contact with the studs. Now, using caulk or expanding foam, seal around the perimeter of each board. This will maximize energy efficiency and keep the foam panels in place.

If you are looking to install on a masonry surface, such as a brick wall, you can install over the top and then cover the insulation accordingly.

If you would like more information on Rigid Foam Insulation, feel free to contact our friendly expert team on 1800 354 717.

Knowing just how to cut foam board and still have the edges look nice can be a tricky thing. Foam boards are frequently used by architects to make models of what they plan on building, to create signs or posters, as a form of insulation, or any number of other things, each of which needs the edges to have a sharp, clean finish.

Foam board can sometimes be referred to as foamcore but, no matter which name you call it by, you might know from experience that the edges love to get jagged when you try to cut it. This is one of the most common problems people experience when cutting foam board.

What do you use to cut foam board?

While you can use anything that has a sharp blade on it to cut foam board, some things naturally work better than others. If you are in a hurry and do not care about the details, you can cut with the first thing you grab.

☆ For example, a pair of kitchen scissors will cut through it if you don’t care about the edges, and even a hand saw can do the work if the board is too large for scissors to handle.

Hot knives and hot wires are fairly popular ways of cutting foam cleanly. The problem with using one of these, besides the melted edges it can leave and the burns it can cause if you are not careful is that it can release the potentially toxic fumes of the foam.

If you use a hot knife or a hot wire, be sure to check the type of foam that you are using to verify that it is safe kind to be cut by these.

☆ A kitchen knife or a pocket knife can work well if it is sharp enough and if you have a grindstone or file to keep them sharp as you cut. These can be a good option and, if going this route, you should pick a knife with a relatively long yet thin blade.

☆ The best option is undoubtedly a utility knife with an X-Acto knife being a close second. The blade of a utility knife is easy to replace at the first sign of dullness, and it can be used for a multitude of other things. If you do a large amount of foam board cutting regularly, you could also consider investing in a foam cutting saw.

Tips for the best way to cut foam board overall

How to cut rigid foam insulation

First of all, when trying to determine just how to cut foam board, you must have a nice sharp blade on the knife or whatever you will be using to cut your foam board. A dull blade will make it impossible to cut without getting jagged edges since the tiniest variance in the blade can affect it.

This fact is especially true since it often requires more than one cut over a line to cut entirely through if your blade is dull. You will be able to tell if a knife is genuinely sharp or not when it comes to foam board because a sharp knife can slice through the whole thing in one smooth cut.

Also, whatever you decide to cut with should be held as horizontally as possible. Doing this will allow more of the blade to come into contact with the board and will give you much better results.

Above all, never “saw” at the foam board at all. Keep your movement smooth from top to bottom and try to not vary the depth of your knife at all while you are cutting.

How to cut foam board for insulation

How to cut rigid foam insulation

Foam boards that are designed for insulation have a different look to it than a regular sheet of foam board does. For starters, it has one side that has ridges or bumps on one side of it, the other side being flat and smooth like a regular foam board.

Even though this foam is made from the same stuff, the inside is different. It is more solid in the center, which is why it is sometimes referred to as rigid foam insulation.

You should cut this kind of foam board with the ridges on the bottom. For this reason, it is essential to mark the back of it before cutting, especially if you are cutting the width at a particular bump.

As before, the best way to cut foam board involves cutting at as much of an angle as possible, and you should also avoid sawing at the foam board. You should also use an extra-long blade for this. Doing so will make sure that the knife can reach all the way through at the angle you are cutting at with length to spare.

Custom insulation board with you in mind! Insulation Supply will happily custom cut rigid insulation board to your specifications and deliver to your company or job-site. In addition to offering virtually any width, length and thickness, we also have a variety of edge types such as tongue and groove, shiplap, furlap and channel that will meet the demands of your project. Our conveniently located, state of the art facility in Northeast Ohio is known for its quick turnaround times. We offer both delivery and store pickup options. Our knowledgeable staff can help you with any questions as we encourage you to call or use the contact form below.

Custom Length and Width

Our hot wire cutting process allows for a wide variety of lengths and widths at any quantity. Both length and width measurements start at 1″ and increase by 1/8″ increments. Max width tops out at 4′ while max length can be up to 9′ for some rigid insulation varieties.

Custom Thickness

We use two methods for changing the thickness of our custom foam insulation. Planing is a process of shaving down the foam board rather than cutting it, leaving a smooth finish. We can also cut the thickness with a bandsaw, which splits the insulation board in half. Boards cut with the bandsaw method are left with a more rough finish on one side. Both methods will leave one side of the foam board insulation unfinished.

Insulation F-Types

How to cut rigid foam insulation

Several types of foam board insulation are available. Each variety corresponds to its own density and pressure rating. All FOAMULAR® XPS products are R-5 per inch of thickness except High-R CW Plus that is R-10 at 1-3/4″, and R-12 at 2 1/8 ” thick.

FOAMULAR 150: 15 PSI & 250: 25 PSI

All-purpose foam panel insulation for masonry and other applications. Owens Corning™ FOAMULAR® 150 & 250 extruded polystyrene insulation is ideal for wall furring, perimeter/foundation, cavity wall, crawlspace, pre-cast concrete, under slab, sheathing and other applications (Not approved for roofing). Owens Corning’s patented Hydrovac® process technology makes the unique closed-cell structure of FOAMULAR® extruded polystyrene insulation highly resistant to moisture, retaining its long term R-value year after year – even following prolonged exposure to water leakage, humidity, condensation, groundwater and freeze/thaw cycling.

FOAMULAR 400: 40 PSI, 600: 60 PSI & 1000: 100 PSI

Owens Corning™ FOAMULAR® 400, 600 and 1000 are high strength extruded polystyrene (XPS) insulation products designed for use in engineered applications requiring additional load-bearing capability such as under slab, concrete floors, foundations, roadways and rail beds, plaza and parking decks and cold storage installations.

FOAMULAR® High-R CW Plus: 25 PSI

The main advantage of High-R CW Plus insulation over other extruded polystyrene boards is its higher R-Value per inch. An R-Value of 10 can be achieved with just a 1¾” thick board. Standard extruded polystyrene requires a thickness of 2” to achieve an R-10. This gives the designer the opportunity to increase the air gap (thereby decreasing mortar bridging and improving the cavity performance) while maintaining the same thermal performance as a standard 2” extruded polystyrene board. Additionally, the designer can also choose to increase the thermal performance of the wall assembly by choosing High-R CW Plus insulation with a thickness of 2⅛”. This provides an R-value of 12 with only a slight increase in board thickness.

Do you need to re-insulate your home? As a homeowner, you may not know much about insulation—but if you’ve been doing some research, you’ve probably seen or heard about the different materials. Foam insulation is used for both new construction and re-insulation projects, but there is more than one kind.

Spray foam and rigid foam (foam board) are two of the main types of foam insulation. What are the differences between them?

Installation Method & Material

Rigid foam insulation can be made of polystyrene, while spray foam is often made of polyurethane or polyisocyanurate. In terms of installation, spray foam is applied wet and expands into thick foam. Rigid foam, on the other hand, is available as a pre-made foam panel that can be cut to fit particular spaces.

Types of Projects

Rigid foam is typically used in new construction projects (rather than existing homes), in unfinished walls, including foundation walls. Spray foam is used for many retrofit (re-insulation) jobs and is ideal for hard-to-reach areas.


The R-values of rigid foam and spray foam insulation vary. Rigid board R-value ranges from R-3.8 to R-5.0 per inch. Polyurethane foam insulation can have R-values ranging from R-5.5 to R-6.5 per inch. Visit the U.S. Department of Energy to learn more.

Air Infiltration

Spray foam insulation can be installed in small crevices, cracks and gaps and can help with air sealing. Air leaks can undermine the performance of insulation, so making sure your home is properly sealed as well as insulated is the best thing to do.

Pros and Cons of Spray Foam

Spray foam insulation is a great choice for insulating hard-to-reach places, sealing cracks that air can escape through, and for achieving higher R-levels. However, it presents a higher upfront cost.

Pros and Cons of Rigid Foam

Rigid foam insulation is more affordable than spray foam insulation and works well in walls, but does not seal gaps as well as spray foam.

Foam Insulation Installers in the Sacramento, CA Area

Whether you need rigid foam insulation for a new home or spray foam insulation, Gold Star Insulation can help. We serve the entire Sacramento, California area and look forward to helping you with your project.

Contact us to learn more about our services or to schedule a consultation!


Where should you insulate in your home? Check out our interactive infographic:

How to cut rigid foam insulation

How to cut rigid foam insulation

Our team can help you save money with a home energy audit and air sealing services.

How to cut rigid foam insulation

Our insulation team installs batt and blown-in fiberglass insulation.

How to cut rigid foam insulation

Environmentally friendly and effective, cellulose works well in homes and buildings.

How to cut rigid foam insulation

Gold Star Insulation is a leading installer of spray foam insulation in the Sacramento area.

How to cut rigid foam insulation

An attic radiant barrier can help keep your home cooler and more comfortable.

How to cut rigid foam insulation

Gold Star Insulation provides home insulation removal services.

How to cut rigid foam insulation

We are committed to saving you money by sealing your attic—which is the main source of air leaks in the home.

Insulfoam’s ENERGY STAR ® certified R-TECH lightweight rigid insulation panel is a versatile do-it-all home insulation for the complete building envelope. Gone are the days of fiberglass splinters, heavy insulation products that are hard to cut, and blown in pieces that take a lot of material for adequate coverage. Builders and homeowners can quickly and economically increases a home’s insulating power with these large lightweight panels that can be cut simply and easily to fit virtually any space, are insect-resistant, and backed by a 20-year thermal warranty.

How to cut rigid foam insulation

R-TECH ® Insulation Panels

R-Tech has been used successfully for numerous commercial, industrial and residential roofing, wall and below-grade applications. Panels are available in a wide range of sizes, thicknesses and compressive strengths up to 60 psi.

How to cut rigid foam insulation

R-TECH ® Insulation Fanfold

R-Tech FF (Fanfold) is a high-performance sheathing consisting of a superior closed-cell, lightweight and resilient expanded polystyrene (EPS) with advanced polymeric laminate facers. R-Tech FF meets or exceeds the requirements of ASTM C578, Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation. In addition, R-Tech FF has excellent dimensional stability, compressive strength and water resistant properties.


  • Environmentally Friendly. Does not contain any dyes, 100% recyclable foam.
  • Water Resistance. Facers provide a surface that is virtually impervious to moisture.
  • Durable. With a polymeric facer on either side of it, R-Tech is extremely flexible and durable.
  • Enhanced R-values. With no thermal drift over its entire service life, the product is eligible for an Insulfoam 20-Year Thermal Performance Warranty
  • Cost Effective. Typically less expensive than other comparable insulation products.

How to cut rigid foam insulation


R-TECH is a top-to-bottom, do-it-all insulation. This versatile rigid foam board can be used for new and retrofit roofing, exterior, interior & cavity walls, siding underlayment, insulating sheathing, continuous insulation sheathing, weatherproofing protection barrier, below grade, under slab, crawl space, perimeter insulation, drainage board and radiant heated floors.

This rigid foam is also easy-to-use for DIY insulation projects. Whether you are insulating your basement, attic, or garage door, R-TECH is an easy way to increase your homes energy efficiency.

Available from home improvement stores nation-wide, R-TECH comes in various thicknesses, panel sizes and fanfold options without loose insulation all over, or pesky and painful fiberglass slivers to avoid.

We can install rigid foam in the attic, basement, garage & crawl space

How to cut rigid foam insulation

Easy to cut but hard to beat. Rigid foam can be cut quickly with a hand saw. Here it’s being used in Dr. Energy Saver’s SuperAttic system to convert an unfinished attic into a well-insulated space.

Dr. Energy Saver by Keeney Home Services installs rigid foam insulation for a variety of applications, including the attic, basement and crawl space. Rigid foam is a popular insulating product for its durability, high insulating value and versatility. Unlike fiberglass batt insulation, rigid foam boards never lose insulating value by settling or compressing. Foam boards shed water instead of soaking it up like cellulose and fiberglass insulation do and foam insulation won’t support mold or provide a home for mice, insects and other pests.

If you’re interested in upgrading your house with rigid foam insulation, call us at 1-715-602-1850 or click the link below to request a consultation and estimate! We are the home insulation experts in Green Bay, DePere, Allouez and surrounding areas.

Types of rigid foam insulation

Rigid foam insulation provides high insulating value with little thickness, but not all rigid foam performs the same. The experts at Dr. Energy Saver by Keeney Home Services can help you choose the best rigid foam for the area of your house that needs insulating.

  • Polyisocyanurate (often referred to as polyiso) has the highest R-value per inch of any rigid foam insulation. Polyiso is a closed-cell rigid insulation that can be used in a variety of applications, including cavity walls, stud walls, masonry walls and vaulted ceilings.
  • Extruded polystyrene (XPS) is a closed-cell insulation, usually pink or blue in color, with a smooth plastic surface. The closed-cell structure of XPS foam board provides a consistent R-value of R-5 per inch regardless of density.
  • Expanded polystyrene (EPS) is an inexpensive insulation material that meets or exceeds all required building and energy codes. EPS rigid insulation is the most versatile of the three rigid foam insulation options and can be used for insulating attics, walls and below-grade areas.

SilverGlo™ sets a new standard for rigid foam insulation

How to cut rigid foam insulation

SilverGlo™ foam panels do an excellent job of insulating basement and crawl space walls.

Recognizing the critical role that rigid foam insulation plays in improving home energy performance, Dr. Energy Saver has developed its own brand of rigid foam insulation. SilverGlo™ insulation can be used to insulate the crawl space or basement, as well as for insulating an attic or garage. The foam boards are easy to cut and install, reducing the time it takes for your insulation work to be completed.

The first thing you notice about SilverGlo™ is that it looks different from other brands of rigid foam insulation. When SilverGlo™ boards are made, they are infused with graphite powder to improve insulating value. Each board also has a reflective coating that acts as an effective radiant barrier. A 2-in.-thick board is rated at R-9, or R-11 if there’s an air space adjacent to the radiant barrier. Thicker boards are also available for applications where more R-value is required. By taping the seams between the boards, our technicians create an effective air barrier, providing yet another energy-saving feature.

As a Dr. Energy Saver dealer, Dr. Energy Saver by Keeney Home Services has exclusive access to this innovative foam insulation product, as well as many other quality insulation materials.

Get an estimate to upgrade your home’s insulation

We would be happy to discuss which rigid foam insulation product would be the best solution for your home. Schedule a custom home energy audit to get a better picture of your home’s energy problems or simply request an estimate to upgrade your insulation. We provide complete energy-efficiency improvements and insulation services in Kimberly, Appleton, Menasha, Neenah, Stevens Point, Oshkosh, Wausau and many nearby areas.

“From the sales presentation to the final install we were pleased with the professionalism of the personnel involved. The detail they went through in preparing the product and the final installation was pleasing.”

Don B

Best way to cut 2" Dow blue board

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Join Date Nov 2006 Country UNITED STATES State/Province New Jersey Posts 112 Post Thanks / Like Likes (Given) 33 Likes (Received) 3

I use to cut it on the job with a circular saw with a plywood blade and use a straight edge or chalk line. Cut it outside, it can make a mess.

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A piece of nichrome wire stretched tight [vertically] between 2 insulators.

Don’t ask me what voltage to run thru it, but a red hot wire should slice right thru it and could basically be set up to rip thru it like a tablesaw.

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For repeat cuts and nice tidy edges, whip up a hot wire foam cutter like a motionaless jig saw from odds and ends of lumber, a 12V 100+ VA transformer, a fan speed control, and a length of 18 gage stainless wire. The wire doesn’t have to actually get red hot but hot enough to scorch wood.

If you can stand the blizzard of foam dust that sticks to everthing including breathing passages and eyeballs, cut it with a power saw of any kind.

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Join Date Nov 2008 Location Israel Posts 986 Post Thanks / Like Likes (Given) 30 Likes (Received) 190

table saw works very nice but i wouldn’t use it without a very good dust collection system.

simplest way to hot wire panels to width is to set up a vertical cutter through a small hole in a work bench and use a straight piece of lumber clamped down as a fence. feed the panel through just as you would on a table saw.

a red hot wire will not hold any tension and will cut all over the place. not that bad if you’re cutting against a fence and the wire is being pulled in one direction but still better to avoid it. for the short piece of wire needed for this you don’t need a lot of volts. a 12 volt toroidal transformer as used in low voltage lighting connected to a dimmer capable of handling inductive loads will work great. or if you only plan to cut foam once and want a simpler set up then use a car battery and adjust the length and/or gage of wire to get the heat right.

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Keeping this in view, how do you cut insulation in pink foam board?

You can either use a special scoring tool, or just make cuts with the utility knife. A score will not penetrate through the board all the way. Bring the foam board up on it’s edge and snap against the score line. The board should easily break apart at the score marks.

Subsequently, question is, can you cut foam board with a jigsaw? If you do it wrong, cutting through foam can be a spectacularly messy job. Before attempting to cut the foam take a well-used jigsaw blade and, holding it with a pair of locking pliers, grind off the the teeth and create a smooth knife edge. Your jigsaw will give you a nice, clean cut through foam every time.

Similarly, what is the best tool to cut foam board?

  1. Long Bladed Utility Knife – Our Preferred Way. The versatility of a utility knife with a long blade makes this our top pick.
  2. A Hot Knife. When a standard knife won’t cut it, you might need some power.
  3. X-Acto Knife.
  4. Hot Wire Cutter.
  5. Foam Cutting Saw.

What can I use to cut foam insulation?

Use a putty knife to cut the foam. If you don’t have a utility knife, a putty knife can work as an alternative. Sharpen the putty knife to give it a pointed edge, then use it in place of your utility knife as you cut through the foam.