Insulating an uneven wall

[Eigenvector]

Now that I have all the wiring done in my basement I'm installing insulation in the walls. It's pretty straightforward but there are a couple of things I wanted to know.

None of the studs in my walls are evenly spaced. I think one section is actually a standard space apart ( whatever that is, 24" or something), the rest are too close together and one is about 1.5 times wider than normal. This is due to the cross beam placement in the ceiling I suspose. How do I know it's too close together - when installing the insulation I have to bunch it up in the space. Is that a bad thing to do? Right now its all scrunched up in there, nothing too tight, but definitely compressed to some degree.

When working insulation around boxes, should I cut the insulation short of the box, then mold a bottom piece of insulation to fit around the box, and continue down the wall? I have a notion of just shoving it in there, but I've been warned about hotspots by doing that.

Lastly, in some sections I have romex running down the stud from the ceiling to outlet boxes and such. Should I do anything with the insulation along the stud where the Romex is routed?

One other thing, is it easier to work with insulation with a pair of scissors or a cutter? I'm using a cutter, but I notice that while the paper is cut evenly, the insulation is typically raggedy. The pink stuff isn't the best medium for a box cutter.

[marson]

to get the maximum insulation value, the insulation must fluff to whatever size it is meant for (5 1/2" for R-21, for example). it should not be compressed and it should not have voids. Don't scrunch it into a joist cavity; cut the insulation to fit. I think it pays to be careful about this--after all, you're paying for the insulation, why not take a few extra hours and get it right? if a joist cavity is too big, run the insulation crosswise. cut around electrical boxes, making sure there is insulation behind the box. split it around wires (or make a slit for the wire to run in.)

I use a utility knive. I don't think scissors would work very well. compress the batt as you cut it. you can get a utility knive with the blade that has snap-off sections..just extend the blade out and you will have a long-bladed utility knive. I've found that works well on thicker batts.

I actually use an eight foot straight edge and cut the batts to width if need be. I like to use a utility knife with

[EXT]

To cut insulation, I use either a snap-off utility knife with the blade extended about as far as it will go, or for other types of insulation I have found that a very large (12") pair of scissors are good, I have even used a sharp pair of hedge shears to trim insulation.

[Lawrence]

Standard distance is 16" on center. Some are 24", but its' rare.

if your spaces are irregular then you have to cut bats to fit. It's better to have it be a bit too large than too small so a certain amount of scrunching is inevitable. It is not ideal but nothing is, especially with regards to fiberglass bats.

I like to cut a notch slighty smaller than the box so it will fit around the box snugly. I then cut a small piece of glass to fit under the box. I size it to overlap the large piece and tear it in half to reduce the thickness.

I use a breakaway style utiliity knife. they can be found usually in the paint section and sometimes with the other utility knives. This style of knife can be extended and retracted. It gives you a nice long blade to work with, several inches. But the real trick for cutting insulation is to press the insulaton down at cut line down with a 2x4. This compresses it and makes it a lot easier to cut regardless of what type of knife you use.

It helpful to have an improvised workbench. I use a hunk of plywood over sawhorses. Then you can cut straight through the glass to the plywood using the edge of the 2x4 as a guide for your knife. When measuring for fiberglass recognize that it is impossible to make a perfect cut. Recognizing that, shoot for having your piece be ever so slightly larger that needed. Then you can do a little scrunching if neccessary to be sure there are no gaps or cold spots. Avoidance of cold spots is a very big deal compared to a small amount of scrunching.

[bowgus]

I get myself a flat surface like a sheet of plywood, a utility knife and say a 1x3. Just compress the fiberglass with the 1x3 and use it as a straight edge for cutting. Usually 2 passes and yer done. As for fitting the fiberglass, just cut it up as required to fill the space ... no need to pack it that much, it stays put. and if yoo're putting vapor barrier overtop it won't go anywhere. I myself have never use the glass with the paper ... just plain glass ... and vapor barrier.

[Steve Barker LT]

Find the company in your area that does the "sticky" blown cellulose. It's the only way to fly. More "R" per inch, and it only cost me $200 more than doing it myself in my 1400 sq. ft.

[Steve Barker LT]

Here's the website of the company that supplied the product my contractor used.

[Steve Barker LT]

Something even better (IMO). I cut a slot about 30" long in a sheet of plywood on saw horses. Lay the insulation over the slot where you want it cut. Push down with your 1x3 ( I used a 2x4) and cut with your ginsu (or any other sharp bread type knife) through the slot. Works great!

[bamboo]

[Eigenvector]

Thanks all for the responses. For the sounds of it I need to change my knife, and maybe get a better work surface. I'll figure it out.

I've been trying to do everything while in place, but I guess once the wall has been measured the rest can be done on a better work surface.

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