Cutting Rigid Foam Board the Easy Way

Geo NR Gee · 01-03-14, 10:43 AM

We have a stack of 4 inch rigid foam board to use in the attic. This looks like a lot cleaner method of cutting rigid foam insulation board than the messy table saw or kitchen knife..........
I suppose if you didn't have a lot then you could do it like they did it on Fine Homebuilding http://www.finehomebuilding.com/how-...nsulation.aspx

But I like this way best....

Video

Daox · 01-03-14, 11:03 AM

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.

jeff5may · 01-03-14, 03:57 PM

this works for me.
$0.75 Handheld Hot-Wire Foam Cutter - YouTube

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

Geo NR Gee · 01-05-14, 02:17 AM

Thanks Guys. I really like the wire cutting tool, but I ended up sharpening the edge of a 4.5" putty knife and cut all of them in about 30 minutes. Now for the fun part of installing them in the attic!

Mikesolar · 01-05-14, 09:18 AM

Quote:

Originally Posted by jeff5may

this works for me.
$0.75 Handheld Hot-Wire Foam Cutter - YouTube

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

Cutting foam with heat produces pretty nasty gasses so I think the blade idea is way better.

MN Renovator · 01-05-14, 10:11 PM

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.

gasstingy · 04-27-15, 05:53 PM

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.

jeff5may · 05-10-15, 09:55 AM

I

Quote:

Originally Posted by MN Renovator

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.

Another easy way is the mighty Rotozip. A shopvac hose placed close to the messy end helps grab the chips and.dust.before they fly away.

AC_Hacker · 05-11-15, 08:38 AM

I had a load of 2" EPS to cut for my kitchen floor, so I set up my contractor-type table saw in the back yard and did the deed all at once.

I had a passive debris catcher bag thingie (old tee-shirt with the sleeves & neck sewn shut) hanging on the out put of the saw, that caught some of the kerf-dust, and what little escaped the catcher bag has now become part of nature.

Overall, it worked just fine... fast and accurate and not nearly the debris problem I had imagined.

-AC

thediyhubby · 06-08-15, 09:08 AM

Looks like a pizza slicer, but works really well.

01-03-14, 11:03 AM	#2
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	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. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

01-03-14, 03:57 PM	#3
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	this works for me. $0.75 Handheld Hot-Wire Foam Cutter - YouTube To cut larger sections or swaths, I rig up a stationary vertical wire section to some jumper cables on the side of a bench. Last edited by jeff5may; 01-03-14 at 04:03 PM.. Reason: words

01-05-14, 10:11 PM	#6
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 940 Thanks: 41 Thanked 117 Times in 91 Posts	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. Last edited by MN Renovator; 01-05-14 at 10:14 PM..

05-11-15, 08:38 AM	#9
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 724 Times in 534 Posts	I had a load of 2" EPS to cut for my kitchen floor, so I set up my contractor-type table saw in the back yard and did the deed all at once. I had a passive debris catcher bag thingie (old tee-shirt with the sleeves & neck sewn shut) hanging on the out put of the saw, that caught some of the kerf-dust, and what little escaped the catcher bag has now become part of nature. Overall, it worked just fine... fast and accurate and not nearly the debris problem I had imagined. -AC __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...

01-05-14, 02:17 AM	#4
Geo NR Gee Journeyman EcoRenovator Join Date: Jan 2011 Location: Seattle Posts: 326 Thanks: 109 Thanked 23 Times in 18 Posts	Thanks Guys. I really like the wire cutting tool, but I ended up sharpening the edge of a 4.5" putty knife and cut all of them in about 30 minutes. Now for the fun part of installing them in the attic!

04-27-15, 05:53 PM	#7
gasstingy Journeyman EcoRenovator Join Date: Feb 2010 Location: Arab, AL Posts: 491 Thanks: 109 Thanked 49 Times in 43 Posts	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.

06-08-15, 09:08 AM	#10
thediyhubby Lurking Renovator Join Date: Jun 2015 Location: USA Posts: 6 Thanks: 0 Thanked 1 Time in 1 Post	Looks like a pizza slicer, but works really well.