What do you use to cut insulation?

[ForceFed70]

I'm going to be installing a bunch of fiberglass batt insulation.

I've always just used a box cutter style knife and a straight edge to cut my insulation batts. But got to thinking that there might be a better way?

What have you guys found works the best? Thanks!

 

[rickairmedic]

Personally a 2X4 and a razor knife has always done the job just fine .


Rick

 

[Will67]

I put a **** piece of plywood under insulation and a 2x4 across area to cut and compress insulation down and cut with utility knife. Change blade as needed. For me the trick was compressing it so I was cutting not ripping the insulation.

 

[beater74]

I use a cheap serrated steak knife and a strait edge to compress the insulation. the knifes serrations and it's long blade allow you to quickly saw through it on a single pass.

 

[james1savage]

I put a **** piece of plywood under insulation and a 2x4 across area to cut and compress insulation down and cut with utility knife. Change blade as needed. For me the trick was compressing it so I was cutting not ripping the insulation.

x2. Works like a charm.

 

[mudhog]

the quickest and easy method for me was to use scissors I got some big sharp ones and you can trim it while installing it to go around things. with the knife you got to lay it down and use a board etc. I had insulator dude helping me and before the day was up he was using scissors too.

 

[Zeke]

Get a box cutter with an extendable blade. Even compressed, insulation has some thickness. 3/4" blade stick out does not work well for me. 1 1/2" does. 2" for R30.

 

[NitroPress]

An assistant.

 

[5.0 Mike]

OK Don't laugh, but I just finished my 3rd car section of my garage and I cut all of the insulation with hedge clippers. They cut the insulation like butter!! LOL

 

[bdkruger1]

I use a 6" painters knife. Works perfectly.

 

[napatoolguy6908]

i use my insulation knife from when i did duct work

 

[Steevo]

A carpet knife has a longer blade and makes it easier for cutting bat insulation.
http://www.amazon.com/dp/B00002N5V8/?tag=atomicindus08-20


Careful, though, because it has two edges to cut yourself on.
They don't call them "****** marys" for nothing.

 

[Milton Shaw]

A large gillotine type paper cutter. I think its a 24" cut. Its square and one stroke and its cut. But hate doing it because of all the little splinters of fiberglass you get when you do fiberglass.

 

[djjsr]

Scissors with about 10" blades. I don't know where I got them but they're not very good quality so it may have been Harbor Freight.

 

[NUTTSGT]

Framing square and utility knife over a sheet of osb or plywood. Fiberglass up and kraft paper down.

 

[nehog]

I use a cheap serrated steak knife and a strait edge to compress the insulation. the knifes serrations and it's long blade allow you to quickly saw through it on a single pass.

That's what I use too... Second choice is a big paper cutter as someone else suggested, but that beats the daylights out of the cutting edge.

 

[jlckmj]

I set up a 2 X 8 foot wide hunk of plywood or OSB on saw horses so I do not have to keep bending over or work on my knees.

I open the insulation and let it roll out, paper down.

I pull the insulation onto the plywood, cut to the desired length with a short 2x4 and a tile knife or box cutter.,

As I am taking the cut piece off the table, I pull the remainder onto the table so it is ready for the next cut.

Works good, and easy on this 58 year old body.

Jim

 

[Regnar]

My neighbor had a nice setup. He set up a work bench on of some saw horses. Took a 1x6 and hinged it off the work bench to compress the installation. Then used and angle grinder with a cutoff disk to cut the bat. Worked like a charm and was quick. He was able to cut about 20 rolls in 30 minutes.

 

[lutter94]

These things are amazing

http://www.cepcotool.com/insulknife/

 

[holdover]

I use either my very old large scissors which are about 8" blade length ( I think they were sheet metal shears for light duty work like flashing, or a hedge trimmer with the blades stoned sharp. Did my house and a 40 X 60 garage with 6" batts with no problem

 

[Brad54]

I have a 8-inch wide, 4-foot long piece of 1/2-inch plywood as a base. I tool a large gate hinge and screwed it to the plywood base. I attached the other side of the hinge to a 4-foot length of 2x4, mounted in the middle of the plywood.
Closed, the 2x4 rests flat on the plywood.
Raise the 2x4, slide the bat in paper-side up, close the 2x4 and it compresses the bat tight to the plywood base. There's your straight-edge.
Run a utility knife across the paper, and with even pressure, it cuts through everything.
A razorblade-type box cutter also works.

I think I might have gone through two blades doing my 32x40 shop, with 12-foot walls. The whole lower half of the walls was 4-footers, so I had to cut dozens of bats in half. I also cut a foot off every one for my 10x10 office with 7-foot walls.

-Brad

 

[Tman]

My neighbor had a nice setup. He set up a work bench on of some saw horses. Took a 1x6 and hinged it off the work bench to compress the installation. Then used and angle grinder with a cutoff disk to cut the bat. Worked like a charm and was quick. He was able to cut about 20 rolls in 30 minutes.

WTF!?!?!?! Fiberglass insulation is bad enough. I was going to make a humorous post about a chainsaw but this **** is just as bad...............Seriously, the glass dust from the cutoff is nasty. Go read about silicosis.

 

[1500hd]

I have a 8-inch wide, 4-foot long piece of 1/2-inch plywood as a base. I tool a large gate hinge and screwed it to the plywood base. I attached the other side of the hinge to a 4-foot length of 2x4, mounted in the middle of the plywood.
Closed, the 2x4 rests flat on the plywood.
Raise the 2x4, slide the bat in paper-side up, close the 2x4 and it compresses the bat tight to the plywood base. There's your straight-edge.
Run a utility knife across the paper, and with even pressure, it cuts through everything.
A razorblade-type box cutter also works.

I think I might have gone through two blades doing my 32x40 shop, with 12-foot walls. The whole lower half of the walls was 4-footers, so I had to cut dozens of bats in half. I also cut a foot off every one for my 10x10 office with 7-foot walls.

-Brad

Same theory here but I used a piece of 3/4" plywood with a slot in the middle to compress both sides of the batt. My base is 20" wide and 8' long with the cutting edge 3' from the end. Stanley has a Fat Maxx utility knife with a extendable blade that works great.

 

[54FordPanel]

Scissors with about 10" blades. I don't know where I got them but they're not very good quality so it may have been Harbor Freight.

That's what I use, big long Harbor Freight scissors.

 

[therealwormey]

Framing square and utility knife over a sheet of osb or plywood. Fiberglass up and kraft paper down.

ditto

 

[ZRX61]

Light saber

 

[jumpingryan]

I use roxul mineral wool insulation whenever I re-model.

Slightly more expensive, but it has a slightly higher R-value, fire resistant, and is easy to work with, and easier to cut than fibreglass. I also like the fact that bugs and rodents aren't big fans of the stuff.

As to cutting it, just use a bread knife. In a pinch, I have used a drywall saw.

R