I have heard comments about mitering bat insulation in this forum.
How is it done so that you get a nice clean cut?
I have bat insulation between my roof rafters, and I need to miter the ceiling insulation insulation to 17.5 degrees, where it meets the insulation in the roof.
This shallow slope is the top part of a gambrel roof. Yes I have air space above the roof insulation for air flow, and a vented ridge and soffit.
Replies
We don't generally insulate our bats around here. We stick with the occasional insulated mouse or dog but the bats are much too quick and don't hold much R value even with insulation. :-) DanT
You have to pump em full of that Great Stuff foam first...also keeps them from pooping in the attic.
Don't miter your bats!
a good Carp will cope his batts
Mr T
Happiness is a cold wet nose
Life is is never to busy to stop and pet the Doggies!!
I think part of the reason you're getting silly replies may be that we don't understand (at least I don't understand) your question. Batt insulation is like fluffy layers of figerglass (or mineral wool, whatever) and comes (usually) in rolls. I don't know how you could miter it. Are you talking about rigid insulation like Styrofoam (blue foamed plastic "boards")? Don't know why you'd need to miter that either. Maybe you could try again to explain what you have? What discussions did you read about this?
I tried to copy a drawing into this message, but no success.
I have (2) 6-1/4" thich fiberglas pieces of insulation.
Insulation comes in batts, (flat) or in rolls.
one over the ceiling, and one under the roof. they intersect at 17-1/2 degrees, as the roof slopes down toward the ceiling.
Being that 2 objects cannot occupy one space, one has to be trimmed at an angle.
I could cut one off short at the point they begin intersect at, but would leave an empty triangular space about 17" wide horizontally, and 6_1/4 " tall.
I don't remember when I saw mention in this forum about mitering batt insulaton to avoid having air pockets
If ya insist on batts..just smoosh it in there..a little compression aint gonna hurt. If ya absoluty want to "Miter" them, try an ele. turkey knife..
Spray foam, ridgid foam, blown insul is a BUNCH more better.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
When I built 15 energy star certified homes the thing I learned is that the insulation job (among other things) needs to be perfect. What I found was the only way I could get close this was to go behind the insulators and correct some of their errors. The first job I ever had in construction was as an insulator, so I'm not afraid of the stuff... Maybe if I had another 15 houses to do, I could have got them educated. On the other hand what the other guys here are trying to tell you is you are being too anal about this. It's not carpentry - it's insulation. If you feel it must be that perfect, go to something other than fiberglass batts. For example, you could rip all the batt insulation out and replace it with 3 - 5k worth of foam...
Matt
Edited 9/2/2004 8:41 pm ET by DIRISHINME