With respect to insulation: Can someone please give me advice on the suitability of converting an existing attic FROM traditional bats between the attic floor joists with nothing in the roof rafters and gable/ridge vents, TO expanding foam sprayed between the rafters/walls with nothing in the floor joists and no vents?
I have read that using the “attic as conditioned space” technique is highly desirable in warm southern climates and is recommended for better HVAC performance.
My house is 55 years old and located in the Northeast, on Long Island in NY. I am planing to replace my central air system (blower/ducts in the attic) and think it would be a great time to remove all of the old/dirty insulation and replace it with foam while at the same time enclosing the space, making it cleaner and more useable for storage.
So far only 1 person I have spoken with (an Icynene applicator) has said this is a good plan. Everyone else–including an insulation contractor that uses a different brand of open cell foam and 3 different a/c contractors–have said not to condition the attic/leave the existing floor insulation in place/add more fiberglass on top. I also welcome comments on whether the attic insulation should be open or closed cell.
Thanks in advance.
Replies
bumpity-bump
From LI too... I added R30 Batt insulation last fall, noticeable drop in the heating bill last year and cooling bill over the summer. Don't know anything about the foam stuff.
Another Long Islander here - I recently had Airseal of Brooklyn insulate our Temple school building (9000 sqft) with Icynene between the rafters. We really had no other option because of the construction of the building and we had to do something. It was costing a fortune to heat and cool and still no one was comfortable. This is our first winter with it so I have no hard facts yet, but the building is now very comfortable even in the worst corner classrooms and is no longer subject to wild temperature swings as it was. Although Icynene is expensive it is a lot cheaper than closed cell foam. Airseal was very competitive on price and did a great job; they were not cheap with the foam at all, installing more than we paid for.
If you have access to all areas of the roof and the dollars makes sense I think this is the way to go. Once the roof is sealed you bring your A/C equipment indoors basically eliminating duct losses to the outdoors. (Naturally you don't want to vent the attic in this situation.)
IMO, adding more FG without air sealing is a waste of money and even after air sealing it's not the best way to insulate for a number of reasons. If you don't do the foam I would either blow cellulose over the FG or (better) remove the FG, air seal and blow cellulose.
Closed cell foam besides being more expensive can have problems with cracking and pulling away from the rafters, but from what I've read it seems more of an application error than a problem with the product.
There's a lot of "that's the way we've always done it" in the insulation business so be careful who you listen to (including me) ;-)
My contact at Airseal is Abba Kloc. We spent a fair amount of money there so if you want a personal recommendation just email or PM me. Here's their web site:
http://www.airsealis.com/index.html
Hope this helps,
Jerry
Thanks for the info Jerry. I tried sending you an email and received an error message...so I'm not sure it got to you. I am relatively new to these pages. How can we get in touch? I would like to chat if possible. I live in south Nassau. Thanks.
Sorry I didn't get back to you sooner. I had a very busy weekend. I sent you an email - how about a first name? BTW, I grew up in the Five Towns.Jerry
Edited 1/15/2007 2:26 am ET by Jerry18
Jerry,
My first name is Nick. I got your email and responded... hope to speak with you soon. I'm interested in the name/# of the blower door guy.
Thanks to everyone who responded...and I'm still hoping that a knowledgeable insulation contractor/builder/etc will chime in on the suitability of using foam in a NEast attic. Some stuff I've read seems to imply that it is recommended in warm climates but I've never heard colder/northern climates mentioned--and as I previously wrote most of the local people I have spoken with recommend leaving the attic vented. My gut is that they are not educated on the subject since foam is still a relatively new product, but I'm not sure.
my concern is that any insulation and ventialtion package should be totally designed and considered together along with placement of VB.
With an older house it gets more complicated. You need advice of people who can see the job on site and who have multiple experience, not just an insulation salesman who is going to make money of th einstall.
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Of course you're right - a house is a system and changing one thing can have effects on the whole system. Maybe I got a little carried away in my response but it seemed the OP already knew what he wanted. In any case, I can also recommend an energy consultant who will do the blower door test and take a more system wide approach. He'll make recommendations to spend money where you'll see the biggest return and he's very reasonable. (He has no vested interest in the sale of any product or services)Jerry
I'm on LI too (north shore Suffolk), and am thinking of modifying my attic insulation system.
If you haven't already, definitely check out the Building Science website.
http://www.buildingscience.com
I also recommend the book "Builders Guide for Cold Climates", which I have.
Seems like foam sprayed directly in-contact with the underside of the sheathing is recommended. Also thinking of replacing the fiberglass between the ceiling joists with cellulose. But after spending some time studying this info, I'm not sure which way to go. So please keep in touch and share your thoughts/experience.
Bart
Hi Bart,
Yes, lets keep in touch. I had one insulation guy offer ThermaCube as a better option than cellulose. It is made by Owens Corning and gets blown in (see the link below). He said the cost is $1.35/sq ft. It seems like a good option, but I am leaning toward removing the old bats in my attic floor and spraying the rafters with open cell foam, which will cost about $4.40/sq ft from the same insulation guy (3.25x the cost of ThermaCube, not including cost of removing the old stuff). He uses Sealection 500, which competes with Icynene. Have you heard of Sealection?
My concern with blowing more stuff over the old is that (1) it may not seal much better than what I have currently, (2) in time all of the new stuff will get dirty in the vented space, and (3) my new AC equipment will remain in a hot attic. I like the idea of foam because it will absolutely seal the attic, creating a clean environment for storage and the AC. I plan to stay in my house for many years, so I should get payback. Spending ~$4000 (plus cost of removal) vs ~$1500 is not a no brainer, but may make sense considering long-term energy usage.
I am still up in the air. Two things I am concerned about are (1) whether or not my existing bats may contain asbestos. (2) if foam sprayed on the rafters will ooze out of the ridge vent in my roof; the Icynene guy I spoke with said no, but did not seem to have experience with the scenario.
Im hoping to get more feedback from the good people on these pages. Still curious why the foam is always explicitly recommended for warm climates but never specifically mentioned for colder/NE climates. Keep in touch.
http://images.google.com/images?hl=en&lr=&q=owens%20corning%20thermacube&ie=UTF-8&oe=UTF-8&sa=N&tab=wi
If you are going to foam the roof rafters, I'm sure you would want to seal that roof vent. Depending on the type of vent the foam may find its way through, but more importantly you need to seal out the weather. You don't want water between the sheathing and the foam. I didn't know the foam option is so expensive. Is it worth it? I will look for other options.My first thought on the ThermaCube is negative. ThermaCube is loose fill fiberglass. I think cellulouse has more sound deadening, less air infiltration, and won't itch. Why replace fiberglass with fiberglass? Seems like Owens Corning made ThermaCube in response to cellulose.I've never seen asbestos in fiberglass batts. If you're concerned post a photo of what you're talking about. I'm a NYS/EPA Certified Asbestos Inspector.I don't think there is a code requiring removal of ceiling insulation if the attic is foamed, makes no sense, but I don't know code. I would leave the floor insulation in-place. (Replace the batts with cellulose) I'm not looking to heat the attic.
I'm now in a house in Northern N.Y, with closed cell foam (corbond) sprayed in rafters. Its a cathedal ceiling thing with no attic. Really works great, warm in winter (with no upstairs heat) and cool enough in summer, Was expensive though.......about 5 g's for upstairs of a 1400sq. ft home, 2x8 rafters and kneewalls.
I did a home in northern Vermont a few years back that had a traditional attic. We had corbond sprayed on the attic ceiling from above to a depth of just an inch or so. It did a great job of air sealing. We had boxed in a few ceiling lites w/ sheetrock and they were sprayed over as well. When house was almost done we had cellulose sprayed over the foam to get r values up to r 45 or so. We still did soffitt and ridge vents so attic had ventilation. I myself (be careful of listening to me) would not be concerned with high attic temperatures if that heat was not making it down to the living areas during the summer. How hot can it get in the North? I know, it may reach 100 degrees or slightly more, but thats really not that much. I'm with the air sealing crowd and if you can find a way to seal all penetrations into your attic , then conventional insulation works fine. Just be real careful about sealing all penetrations (easier said than done). That one inch of foam really did the trick though.
good luck.
Nick,Sorry it's been so long getting back to you. Here is the energy consultant I used:http://www.home-energysolutions.com/I was very happy with Glen and the job he did for us. I'm wondering if you ever called Airseal and how your project is going?Jerry
I would probably leave the fg batt in place, even if I elected to install the foam in the rafters.
I'm not sure that increasing the volume of air that you are heating and cooling makes any kind of sense. It takes energy either way, that is in proportion to the volume you are trying to control. Increasing the insulation around the ducts in the attic makes sense, insulating and controlling the entire attic to avoid the heat transfer from the ducts to and from the ducts, doesn't.
If you increase the r-value enough you may have a savings even with an increased volume, but it won't be as great of a savings as if you had not increased the volume.
Although increasing the volume, or more properly the area of wall/roof etc. in contact with the outdoors or unconditioned space would at first glance seem to be a stupid thing, what you've got to remember is that air infiltration results in a larger proportion of heat loss than dissipation through properly insulated walls etc. So it comes down to how you can control air leakage. The ceiling plane and ceiling/wall junction are notoriously leaky to air in older construction- and even in new construction done poorly.
If it's possible to do the proper job of air sealing to deal with the infiltration problem at the ceiling level, PLUS a very thorough job is done of insulating the ducting, that will result in a lower heat loss building than spraying the entire attic space and turning it into conditioned space. But chances are, it'd be far tougher to do that effectively than to simply close the whole envelope with spray foam by conditioning the attic space. If you insulate the attic space but don't heat it, and leave the ceiling insulation in place, the air space in the attic will act as an additional, though poor, resistance to heat transfer out of/in from the roof.
Thanks Jigs.
I think by code---if you spray the rafters then the attic floor must have no insulation.