easiest way to cut insulation

[xscorex]

wasnt paying attention, bought some insulation to put in my garage then got home and it looks like the guy who built my garage has put studs at "around" every 10 to 13"s. cool for making it sturdy, poopy for stuffing in insulation. now I have alot of cutting to do. You guys got any tips? just use a sharp utility blade? Seems easy but tiresome, didnt know if the pros had any secret tips for a situation like this

 

[Falcon67]

Long board -2x4 or 1x4- for a straight edge, squish it flat, sharp until knife. Gloves and mask too - you don't want those fibers in your skin or lungs.

 

[sammm]

Straight edge and a utility knife to follow along it.

 

[logical]

Ceremonial ribbon cutting sissors:

Seriously, I use a metal yardstick to squish flat and a utility knife.

 

[metal1313]

i usually take a 4ft piece of sharp aluminum angle to use as a strait edge, a sharp knife and a piece of wood, usually ply, under the cut. it cuts much better and sharper that way

 

[GarageEnvy]

Funny this should come up right now. I did a little insulation work on the house a few weeks ago (seems like the original builder didn't feel like insulation was needed in the walls) and struggled with the utility knife. This week I had the pros do my new 1800 sf garage because of the size and the fact that they do it cheaper than I could buy the material. I noticed they were using kitchen knives. One guy was using a bread knife and the other guy used a regular large bladed knife with a little serration (sp?) on it.

 

[Racer_X]

How about the insul-knife?

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

I've never used it on regular insualation, but I bought one for cutting extruded polystyrene. It worked better than everything else I tried. If you do get one, you'll definitely want to get a sharpener as well, as it is kind of dull from the factory.
I bought mine through Amazon. If you scroll down a little on this page, you'll also see the sharpener I bought with it:

http://www.amazon.com/dp/B0009MZI4W/?tag=atomicindus08-20

 

[Striker]

Here is the correct tool you need:

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


EDIT:
Heh, the previous poster beat me by a minute on the recommendation.

 

[kenfath]

I just watched professional installers insulate a garage. The knives they used were Hyde Tool 60780 Square Point Knife, 8-Inch by 1-Inch/14 Gauge/Wood Handle. It is a basic flat blade knife with edges on both sides. They had a sharpening stone and would sharpen the blades about every 30-minutes. There was a lot of custom cutting. They split 24" unfaced R19 to fit between 12" OC rafters. Three kinds of insulation products were used and the knifes cut it all with ease. The blunt end was used to pack and/or guide the insulation into place. The only other tool they used was a two-prong pole for placing the insulation between the joists and studs. It was very impressive watching them work!

 

[FordToughF250]

When I put windows in, I used a long piece of cardboard and just used a utility knife, it works great

 

[Falcon67]

If I used a big knife, there'd be a 911 call shortly.

 

[67ShortFleet]

I use a fish fillet knife. Works real well on thick foam also.

 

[KCarGuy]

I can see if someone but a stud in ever 12"...sure is better than every 16" for strength...
But every 10-13"...that guy needs to get his "*** kicked"

How the hell are you expected to install drywall is the studs dont end up every 4 feet or 8 feet...cutting insulation would be the easy part.

Buy that guy a tape measure for Christmas!

 

[Falcon67]

You get the opposite problem with an old house. Ours is 24" OC (and I built the shop like that) - you can't hardly by the rolls in 22 1/2" anymore, only batts. Almost everything that is stocked now is for 16 OC construction.

 

[expatriated]

Ceremonial ribbon cutting sissors:

Seriously, I use a metal yardstick to squish flat and a utility knife.

That looks like what they used in the Big Leibowski dream sequence!

 

[mdbeck1]

I can see if someone but a stud in ever 12"...sure is better than every 16" for strength...
But every 10-13"...that guy needs to get his "*** kicked"

How the hell are you expected to install drywall is the studs dont end up every 4 feet or 8 feet...cutting insulation would be the easy part.

Buy that guy a tape measure for Christmas!

I helped my BIL on a bathroom remodel a few years ago. The framers put studs in wherever they wanted. I mean I had studs at 12", 24", and everything in between. HOWEVER... They always had one at 8'. I REALLY wanted to just tear the exterior wall of his house out and start over.

 

[mdbeck1]

Oh, almost forgot...

To the OP. I use a utility knife with an aluminum ruler to cut insulation.

 

[Nosman]

Bread knife with Roxul, works like a dream!

 

[rwhite692]

When I insulated my garage, to cut the insulation to length I used an old (but extremely sharp) kitchen knife with about an 8" blade.

With the insulation laying paper-side down, I put a piece of old 1/4" masonite on the floor under where I was cutting, and I laid a strip of wood (old piece of 3/4" plywood, about 4" wide x 36" long) across the insulation, compressing it flat and providing a straightedge to follow with the knife.

One swipe with the big ol' kitchen knife, and it was cut clean all the way through.

I got a lot better results this way, vs. trying to do it with a utility knife.

Another tip: If you have to make many identical cut lengths of insulation, measure it out once and make a tape mark on the floor, so you can just roll-out and cut piece after piece, without having to measure....

 

[qdvuu]

I just got finished helping a buddy tear out a lath and plaster interior wall and rebuild it with much attention to sound deadening, and the insulation he used was made from a cottony material (he said it is blue jean scraps). The house is about 70 years old and the studs are nominally on 16 inch centers, varying a couple inches, so some of the precut batting needed to be cut to fit. We used his tablesaw with the blade mounted backwards. Worked like a champ!

 

[nate379]

Can't just smoosh it in there?

 

[Torque1st]

Using a belt sander with a course belt will produce nice little serrations that make it easy to cut insulation with an old knife. It will have to be resharpened often but a quick pass over the belt will do it.

 

[OccupantRJ]

Can't just smoosh it in there?

That's akin to the subject of using PVC for airlines.

 

[mdbeck1]

Using a belt sander with a course belt will produce nice little serrations that make it easy to cut insulation with an old knife. It will have to be resharpened often but a quick pass over the belt will do it.

Steal your wife's fingernail board (emery board) and staple it to a piece of 2X4 and run the box knife blade over it a couple of times. It will give you a rough edge REAL fast.

Just don't let the wife know where her emery board went.

 

[nate379]

Explain.

Smooshing a 16" wide piece of insulation to a 13" cavity isn't going to make the earth stop rotating!

That's akin to the subject of using PVC for airlines.

 

[OccupantRJ]

Explain.

Smooshing a 16" wide piece of insulation to a 13" cavity isn't going to make the earth stop rotating!

Basically when you compress the insulation, it loses some of it's insulating capability, as it depends on the dead air space to work properly.

 

[Racecarl]

I have used a home-made insulation cutter that works great to cut insulation to length. Find a 2X4 about a foot longer than your insulation is wide. Cut a saw kerf through the board, leaving about 4" at one end uncut. Using mechanic's wire or a low E guitar string, make the wire 16" longer than the board you ripped. Secure one end of the wire to the unsawn end of the board and make a pulling handle out or a dowel or bolt to put on the other end of the wire.

To cut the insulation, place it kraft side down on the floor. Throw the wire and handle underneath where you want the insulation cut, leaving the uncut end of the board on one side and the cut end on the other. Get the wire started in the cut groove. Put one foot on the uncut end of the board and the other foot on the cut end, which smashes the insulation down. Pull up on the wire briskly, and the wire will cut the insulation nicely.

This also works on unfaced insulation.

 

[OccupantRJ]

Racecarl, that's pretty damn clever. I'm going to be insulating shortly, I'll have to give that a try.

 

[SteveU]

One thing I haven't seen mentioned,wear gloves & a long sleeve shirt when you work with fiberglass insulation. The stuff is nasty to bare skin & will irritate & leave red bumps where little pieces break off under the skin, found out first hand while insulating my attic with the stuff. A face mask isn't a bad idea either to keep it out of your nose/mouth.

 

[nate379]

It bothers some people worse than others. My Dad can't get 10ft from the stuff and that happens while I could eat it for lunch and be fine.

 

[NUTTSGT]

I can see if someone but a stud in ever 12"...sure is better than every 16" for strength...
But every 10-13"...that guy needs to get his "*** kicked"

How the hell are you expected to install drywall is the studs dont end up every 4 feet or 8 feet...cutting insulation would be the easy part.

Buy that guy a tape measure for Christmas!

A kick to the nads would be cheaper.


I use a 2x4 and utility knife.