Hi all, I had a major house fire six weeks ago and – although the frame is still standing – the entire house (two stories) had to be gutted to the studs. The house was built in 1971 and has 2×4 construction. I live in Maine, so the house was never very easy to heat with the old fiberglass insulation. Having lost the house and almost all of our possessions, I’m trying to see the silver lining here that at least this is a chance for better insulation in the future…and maybe get a break from running the woodstove 24/7. With 2×4 walls, though, I know I have limited options. My General Contractor is recommending dense pack insulation with a mesh – in order to do this he needs to construct a 2 inch deep sheathing wall inside the existing frame. I’ve looked online and I think this is referred to as a Mooney wall. My concern is that I’ll lose 2 inches x 2 inches in all the room interiors. I know it doesn’t sound like much. But it’s not a big house. I’m a single mom with two teenage boys and two Golden Retrievers. The house comes in around 1700 sq right now. It’s always been just fine for us as it was…but at the same time I’m not sure how I feel about losing even a few inches of space in every single room. My General Contractor PROMISES me I won’t even notice the lost space when the walls are up, and that the ease of heating and better R value will more than outweigh any minor inconvenience with the lost space. Anyone had experience where they’ve done this insulation method – in their own homes or for customers? Any thoughts on whether the loss of space will be noticeable/regrettable or not? Thank you so much for your thoughts!!
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North,
The Mooney Wall you mention was given that name right here at BT several years ago. A search of that in this forum should provide many threads filled with info.
https://www.finehomebuilding.com/?s=Mooney%20wall&es%5Bpost_type%5D%5Band%5D%5B0%5D=forum&referer=
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EDIT TO ADD: I am sorry to say your hunt will be tenuous at best. One of the things Taunton managed to do is lose content here from this forum. The forum goes back over 20 years and has been piped to the world over a few different servers or whatever their called. With that they managed to lose a hell of a lot of content. Damn shame and something to be not proud of. If you work your way up in time in those linked threads you might get lucky to find some of the original info.
SORRY!
Feel free to dash a letter off to FHB and Taunton!
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Not sure if the design was actually hatched here but discussions between Mike Smith, Tim Mooney and others sure laid out the pros, cons, and methods.
Your 2” loss is only at exterior walls so suggesting it would be not too noticeable seems like no BS. You are breaking the full contact of your framing heat/cold to the outside while gazing the thicker insulating ability of the dense pack. Whether it betters or equals the value of flash and batt, is where I might make my decision.
Best of luck.
Thanks Calvin! I had looked through some of the old threads - interesting stuff and I feel like I've learned a ton. I haven't seen anyone specifically commenting on the loss of floor space being an issue for the homeowner so maybe it's true that it won't be noticeable. I spoke to my town code officer here in Kennebunk and he agreed with my GC. I won't notice the loss. I appreciate your time and your thoughts.
If you have an inkling, send a letter to Taunton and mention the valuable thread loss. Evidently they’ve tossed many of letters regarding thread loss in the trash....
I'm sorry to hear about the loss of your home and possessions.
2x4 wall construction and fiberglass batt insulation was standard in Canada until few years ago and you should be fine with that. There are so many areas that contribute to heat loss that you shouldn't single out this one particular part. Windows for example have an immense impact on heating costs. Other than the loss through windows, most of the heat loss is through the ceiling (attic). Limiting air infiltration through proper sealing (prior to drywalling) is also very important. If you're still concerned about heat loss through 2x4 walls, you could apply a foam insulation product to the exterior of the home,--beneath the siding material. The choice of a different cavity insulating material (foam, that would be more expensive) for use on a side that is subject to a lot of cold wind might prove cost effective.
Designing an energy efficient home involves due consideration and the proper choice among many possibilities. Simply adding more fiberglass is not necessarily going to achieve the desired results.
It is a complex subject and in conclusion, I would strongly suggest that you hire a consultant with considerable experience in building an energy efficient home. He/she will be able to advise you based upon your budget and steer you to an experienced and reputable general contractor. It will be the best few hundred dollars of insurance that you ever spent.
Best wishes for your future.
I live in Maine also, we are renovating a 1950s house with 2x4 walls. Have you calculated the expense in labor and material to add 2" of interior framing to every wall? It makes more sense to sheathe the exterior with rigid foam board then add the siding on top of that. This adds insulation and doesn't modify the interior space. This technique is discussed ad nauseam in these forums, youtube, and other building sites like Green Building Advisor.
Personally we aren't tearing off our siding, we simply replaced the ancient mineral wool batts with Rockwool batts where we opened the walls. One vendor tried very hard to sell me on blowing insulation i to all the cavities through holes drilled in the exterior, which strikes me as an enormous effort for very little gain.
Good luck,
Tim
Thank you everyone. I appreciate the thoughts. I am not tearing off the siding either. It turns out that my insurance policy doesn't cover any required code updates (PSA: check your homeowners policy for Ordinance and Law coverage) so I am on the hook for those, unfortunately. Trying to figure out how to make the numbers all add up and spend what little extra I have on the right upgrades to the house. Insulation is one I just can't seem to make a decision on. Tim, Rockwool batts in 2x4 construction will give you about R12, correct? You're comfortable with that? I am not one to keep my house at 75 all winter - but it would be nice to think it won't be drafty anymore after this process is over.
2x4 Rockwool is R15. Which is better than the R?? the 70 year old mineral wool provided! I'm not going to try to make our modest house into a net zero energy laboratory, just improving the insulation is going to score some big gains.
I assumed your siding was trashed in the fire so you had more options. Good luck!