Cutting polyiso insulation.

[wantacoe]

How do you cut polyiso insulation? I tried cutting one side with a razor knife and braking it like with sheetrock but it doesn't give a clean cut. It is 3 1/2" thick so my circular saw doesn't make it either. Any ideas? Thanks

 

[PugetDude]

On my last basement remodel I cut mine with my tablesaw, shop vac on the exhaust port.

 

[PWC Repair]

i cut my 3" foam board with a sawzall. Turned the blade around and pushed the sawzall so I could see my line.

 

[Kaizen]

Japanese type hand saw (pull saw cut). Blade should be several inches across. Some dewalt ones only an inch that ****.


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[Lynden]

CRL makes extra long utility knife blades (2-1/4" of the blade is exposed). You could make repeated cuts on both sides of the board.

https://www.walmart.com/ip/CRL-Extra-Long-Utility-Knife-Blades/860956082

 

[19D2P]

These worked great for me.


Festool 493656 S 155/W Foam-cutting Jigsaw Blade, 6 Inch, 3-pack https://www.amazon.com/dp/B0033LBOJY/?tag=atomicindus08-20

 

[Sherk]

Sharpened putty knife and a long metal ruler as a guide. I lined a basement with foam board this easy. Worked well.

 

[rustyjames]

I use a straight edge and a regular small handsaw. Power saws make a huge mess unless you do it outside.

 

[Natty Bumppo]

I did mine on a table saw...outside, in a strong wind. Nice clean cuts and fast. But it does make a mess.

 

[DFB]

No matter how you cut it seems to make a mess

Could also try using an extendable type razor knife the ones with the snap off blades, there usually really cheap @ at that thickness still may have to cut from from both sides though

 

[earlybirds]

Sherk has the right idea. This is how I did my shop insulation using polyiso and pink XPS foam sheets. Sharpened both sides of a longer putty knife and used a long metal ruler as a guide. Works great.

 

[Natty Bumppo]

How do you cut polyiso insulation? I tried cutting one side with a razor knife and braking it like with sheetrock but it doesn't give a clean cut. It is 3 1/2" thick so my circular saw doesn't make it either. Any ideas? Thanks

That looks like the stuff I used, which has a fiberglas facing. However you cut it, I'd recommend wearing a mask of some kind. Nasty stuff.

 

[OccupantRJ]

Try an electric carving knife. They are great for cutting soft foam products like upholstery foam.

 

[strutaeng]

Yeah, watch out for the fiberglass. It itchy. Gloves are a must.

I used a long snap away knife and bought an "insulation knife," but the insulation knife was worthless.

https://www.homedepot.com/p/Milwaukee-6-in-Smooth-Blade-Insulation-Knife-48-22-1921/205935391

https://www.homedepot.com/p/DEWALT-25-mm-Metal-Body-Snap-Off-Knife-DWHT10045/202710467

The snap away worked okay for short cuts. I think I also used a reciprocating saw for some cuts. I have since bought a handsaw that I use a lot. I think this is probably the best tool to use. Japanese-style saw would be too slow.

https://www.homedepot.com/p/DEWALT-15-in-Tooth-Saw-with-Aluminum-Handle-DWHT20544L/202985585

I had a job once inspecting a roof installation and saw the pros use a drywall jab saw for little cuts. I can't remember how they made the long cuts. It's still messy because they had a leaf blower on the roof.

 

[glend123]

Grind the teeth off of a jigsaw blade and use it like you normally would. I just did this for the first time a couple weeks ago and it worked great! No mess either!

 

[Danno1]

.


I have an old large kitchen knife that I use for this. Sharpen it occasionally with a belt sander.

The guys in the shipping dept at work use an electric carving knife (mentioned above somewhere).


.

 

[dogdog]

maybe try one of these ?

https://www.harborfreight.com/130-watt-heavy-duty-hot-knife-60313.html

I got one but can't tell you if it is good.. it's going to be a while before I will used it.

 

[engineer2]

Steak knife, or bigger kitchen knife for 3.5"

 

[RKA]

Grind the teeth off of a jigsaw blade and use it like you normally would. I just did this for the first time a couple weeks ago and it worked great! No mess either!

Bosch and Festool make a blade for cutting this insulation. It's the only way I've found to cut insulation without making a mess. Almost zero dust! Grinding down a jigsaw blade would probably get you pretty close.

https://www.amazon.com/Bosch-T313AW3-3-Piece-Special-Materials/dp/B001J0U1HC/ref=sr_1_2?keywords=bosch+jigsaw+insulation&qid=1575916296&sr=8-2

 

[Hooked]

I use a 6" or 9" filet knife. Sharp and thin blade slices right through it.

 

[NUTTSGT]

Steak knife, or bigger kitchen knife for 3.5"

I have an old steak knife in the garage to cut rigid insulation. I've never used it to cut that thick of insulation though.

 

[Kurt4440]

The hot knife works well, but, use it in a well ventilated area.

 

[spudley]

Has anyone tried a band saw? Not there yet but that's what I'm planning on using.

 

[DFB]

Just about any saw blade will cut the polyiso

But using a smooth solid blade the better of you be for the mess

Anybody seen this yet

https://www.amazon.com/dp/B00KM0RLUU/?tag=atomicindus08-20

 

[Lynden]

My brother made a hot wire tool which he used to cut foam parabolic reflectors for two up-firing speakers he built.

https://www.google.com/search?clien...+insulation+with+a+hot+wire&ie=UTF-8&oe=UTF-8

 

[1slov6]

I am currently installing the same poly insulation and I have been using a circular saw, then a hand saw to get the last little bit that the circular saw does not reach. Sure its messy but works great.

 

[Kevin54]

Momma's kitchen knife or her electric carving knife.

 

[Evilunclegrimace]

I use one of those cheap knives that they advertise on the TV, the ones that will cut a pop can in half and then cleanly slice a tomato.

 

[dutchgray]

My brother made a hot wire tool which he used to cut foam parabolic reflectors for two up-firing speakers he built.

https://www.google.com/search?clien...+insulation+with+a+hot+wire&ie=UTF-8&oe=UTF-8

Hot wires don't work on this type of insulation (well they can cut it but you need loads of heat and it gives of toxic fumes) we use a table saw with extraction to cut straight lines or a jigsaw for curves or a pad saw to cut a hole by hand to jam a pipe through etc.

 

[walrus]

Circular saw with blade in wrong direction. I've read that sonewhere but never tried it. I cut mine outdoors.

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[Ray2.0]

The hot wire is the way to go , it cuts clean straight or curved lines and no mess

 

[dfiler2]

The jig saw blades work great and without a mess.

 

[wantacoe]

I am going to have to cut about 300 pcs of this stuff so a slow jigsaw type would take forever. This stuff has a tar like paper on each side so I don't think the hot knife would work. A circular saw is probably the best way to go but it is 3 1/2" thick so would have to cut from both sides.

 

[rust in the eye]

You can score it with a utility knife and crack it or I've also used a serrated bread knife.

 

[NUTTSGT]

Has anyone tried a band saw? Not there yet but that's what I'm planning on using.

How wide is the throat of your bandsaw ?

 

[In2toys]

I use my buddies Altendorf sliding table saw with dust collection.

 

[foodie]

The jig saw blades work great and without a mess.

Great video thanks for the link. I have more XPS to cut and will now use my Bosch jigsaw with the soft blade the video suggested.

 

[rburke65]

Bread knife with the serrated edge

 

[rustyjames]

I am going to have to cut about 300 pcs of this stuff so a slow jigsaw type would take forever. This stuff has a tar like paper on each side so I don't think the hot knife would work. A circular saw is probably the best way to go but it is 3 1/2" thick so would have to cut from both sides.

That the stuff typically used on roof decks. I think since you're dealing with that thickness and amount a table saw setup outside would probably be the way to go. You could try scoring both sides and snapping but that might be more effort in the long run.

 

[wantacoe]

Hmmm, just watched the video using the soft cut Bosch blades. It actually cuts pretty fast with no mess. I am going to give it a try. I will post results but it may be a couple weeks before I get to use it. Thanks for all the replies.