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nureng75
Widen Walls

I want to widen my exterior walls from 2x4 to 2x6 for increase insulation purposes. I was going to nail and glue on an additional cut down 2x3 board to the existing 2x4 to increase the depth of the wall cavity to 5 1/2". Does anyone have other suggestions for increasing the wall cavity size?

A. Spruce
Re: Widen Walls

Sounds like a lot of work for very little gain. Have you considered foam insulation, which has higher R value and seals out drafts? I'm not personally a proponent of foam, however I think it does have it's place.

nureng75
Re: Widen Walls

I have, but don't like the idea of not having the ability to run future wiring or other cable in the wall.

As per the cost ratio I have not research the foam. For the additional stud and insulation approx cost is $200.

Sombreuil_mongrel
Re: Widen Walls

Put 2" rigid foam on top of the studs on the exterior walls, then drywall over it. Just use longer screws. You keep the existing insulation
Casey

jkirk
Re: Widen Walls

furring out walls is pretty common when renovating old homes, ive done it quite a few times, both to accomodate r-24 which is the new standard and to make the old wall line up with the 2x6 walls in the addition

as for spray foam, the 4lb foam is close to r-7 but as it cures it shrinks down to roughly r-6.2 / inch so you be very close to a r-24 as opposed to the existing r-12 in the 2x4 wall. most homes i renovate typically get completely stripped of the siding on the outside then we add 1 " foam to the outside. this give the wall an extra r-5 rating plus the foam acts as a thermal break which allows the wall to perform better for heat retention. much less heat is lost through the studs

HoustonRemodeler
Re: Widen Walls

Another advantage of using sheet insulation under drywall is a much better air seal against air leaks. The foil tape will make a perfect vapor barrier. Of course the vapor barrier on the inside of the home is best suited for homes in cooler climates.

nureng75
Re: Widen Walls

I have a follow-up question to your suggestion. Will a stud finder be able to detect a stud through the rigid insulation, so if I did need to anchor something into a stud I would not be just poking-and-hoping.
Oh and the existing insulation is from 1945. So to my best knowledge it is probably not good for insulation purposes and health issues. Yes, I am taking the precaution’s to remove it without minimally disturbing it.

HoustonRemodeler
Re: Widen Walls

The biggest thing you can do to reduce your energy bills is to;

1- Insulate your attic. Make a huge effort to seal all drafts.
2- Seal all drafts. Reducing or eliminating the "chimney effect" greatly reduces energy loads. Not only the air in, but the air going out as well. Check light fixtures, outlets, pipe holes, ducting, bath vents... Vapor barriers work on this principle.
3- Insulate the floor under your living space. Include a vapor barrier.
4- Insulate the walls. This is last for the simple reason; heat rises. While there is some thermal loss through the walls, the floor and ceiling have a far greater effect IMHO, due to the chimney effect.

My home was built in 1920 without insulation. I have insulated the attic and under the main floor. The walls still aren't insulated, but I cut my energy bills over 50%. Insulating the walls here isn't cost effective living in a semi-tropical area.

jkirk
Re: Widen Walls

the stud finder wont be able to detect studs through 2" of foam, your best bet is to mark the locations of the studs on the ceiling and floor with simple lines coming out from the stud. if the floors are finished you can still do it just run a strip of masking tape on the floor and make your marks on that. the ceiling wont matter because you will be taping the joint anyway then repainting

Sombreuil_mongrel
Re: Widen Walls

A rare-earth magnet will be able to find the drywall screw heads under the 1/16" of mud. The screw heads lead directly to the studs (in an ideal situation).
Casey

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