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Home is about 5-1/2 years old. Walk-up attic is unfinished with builder code insulation in rafters. It's freezing up there in the winter and hotter than blazes in summer. You can actually see outside through the gaps in the rafters. Is that normal? Anyway, I would like to make my home more energy efficient in general and wondering if better insulation in the attic might help and whether spray foam vs. other is recommended. Thanks.
If you mean you can see outside via a gap in the sheething at the base of the roof, that's your eaves vent.
Better insulation is one of those, it depends. It depends on the design of the roof, design of the attic, what you are planning to do with the space, how much you have to spend and other factors. Insulating so that you have a fully insulated attic is not the same as insulating for the living space below. What product to use is secondary to what needs to be done to make the spac an insulated attic.
I sure hope your attic floor is insulated. You want to keep the heat in the main living area in the winter, not up in your attic. IMO an unfinished attic should be closer in temperature to the outdoors than the temperature of the main living area. I went searching for that answer to my opinion, and found some people who technically know what they're talking about in that regard here.
Spray foam seems to be more commonly used as a wall insulation than an attic insulation; typically attic insulation is blown in loose-fill fiberglass or dry cellulose. Between the two I prefer the blown fiberglass (preferably the pink Owens Corning brand) since it doesn't settle with age like dry cellulose does, thus maintaining its R-value for a longer period of time.
And FYI, if there is already blown-in fiberglass insulation, you must top it off with more blown-in fiberglass insulation, since any other types of insulation would be too heavy to place on top of it and will decrease the R-value of the old insulation.
Firstly I know that in my region (suburban Chicago) there are HUGE variations in how effectively trained the various insulation crews are. In my experience the worst trained crews are those using blown fiberglass. Fact is it is darned near impossible to really bust a wall or overload a ceiling with the cottoncandy-like strands of lightweight fluff and some firms hire utter idiots that will NOT really install anywhere near enough material... You need higher skill to do a safe job with cellulose as it CAN deform walls / ceilings especially the moistened "dense pack" guns. Even more skill is needed to make sure walls are not over topped with expanding foam as a bad crew member can add DAYS of "foam trimming" to a crummy job. Thus the potential for low skilled installed to do a poor job and not really be discovered is somewhat inversely related to the likelihood that even a long established business will unleash a "rookie" that does nothing noticeably WRONG but not a "by the book" installation that really is effective...
Secondly the durability of various products is MARKEDLY different -- while it is true that cellulose can "loose its fluff" and thus suffer degradation of R-Value I have literally seen blown fiberglass pushed away by drafts in attics and thus in applications where batts can be used cost effectively I greatly prefer them as a "base" in the joist bays. Cellulose is typically heavier but has its own problems with not just compaction but also sliding inside a sloped ceiling. Expanding foam suffers from none of these problems PLUS is generally an excellent vapor barrier as will as draft proof and highly resistant to insect / rodent infestation...
Acoustic characteristics of mineral wool batts is generally superior to sprayed foam, but that is really its only major plus...
If you have blown fiberglass and it is not performing well it may make sense to have it all vacuumed out and a better product used. If you can afford it spray foam is generally the premium choise. With a really "by the book" installer blown fiberglass can be a good choice too, but finding a perfect installer is hardest. The extra durability of batts may make that a good choice. If done 100% perfectly and used with right stabilization techniques blown cellulose can be extremely cost effective...
I sure hope your attic floor is insulated. You want to keep the heat in the main living area in the winter, not up in your attic. IMO an unfinished attic should be closer in temperature to the outdoors than the temperature of the main living area. I went searching for that answer to my opinion, and. found some people who technically know what they're talking about in that regard here.
You don't want both the rafters AND the attic floor to be insulated. One or the other.
I can't count how many times I have moved or removed attic insulation so I can get to the wiring. That is easy with fiberglass, but would be impossible with spray foam!
Then ok for attic to be cold if it is just an attic. What counts is the ceiling of the room below the attic. Is that ceiling cold? If yes, add more insulation to attic floor.
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