Need an insulation expert!
I’m building a new home and it’s at the insulation stage. It’s 2 story with a steep pitch roof.(8/12 for the main part of house, 12/12 over the garage bonus room and 2nd bonus room over the master bedroom) The attic is vented and has soffits. I’m in zone 2, hot and humid south Georgia.
I had a spray foam guy offer quote 5 inches open cell (r19) on roof line and open or closed cell @ r13.
I’m concerned about not being at code but some literature suggests r20 spray on roof is ok.
I have radiant barrier foil backed osb on roof decking. I don’t know if spray foam would negate that or not.
What would you do? I’m completely tapped out of money!
Side note, getting r11 fiberglass between floors and rooms for sound proofing…
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Building house first, then designing? Ok, I apologize, but it seems to be so common that it bears pointing out to others who may be considering building.
Back to your immediate issue - I believe that it's common in your area to have the HVAC equipment in the attic. Is that the case here?
Also, I may be slow, but I'm confused when you say you have a vented attic, and then talk about insulating the roof, instead of the attic floor. Can you clarify (or point out why I'm slow?)
Well, I had a design in the beginning! But there was some confusion from the builder when we went over insulation. They offered flash and batt, which I was told was 0.25" spray foam and batts over that. That, from what I read, was insufficient, so I told them I wanted to go with wet (damp) spray cellulose, which I was told would be the same price.
Flash-forward to now when we were getting closer to the "insulation phase" of construction. When I asked about wet cellulose, they said they couldn't find anyone to do it and had heard bad things about it causing mold and such. Being that I didn't want flash and batt, I got a quote on full spray foam which is where we are now.
After an on site evaluation from the spray foam guy, nothing was brought up about my vented attic, and I didn't think about it until now. And knowing that I paid $600 extra for foil backed roof decking, I hate to know that money is wasted if I decide to get spray foam.
I hate that plans had to change. I wanted blown-in cellulose in the ceiling and wet-cellulose in the walls. My budget is about $8,800 and that's STRETTTTCHED. Here's how my estimate breaks down:
Spray Foam Open Cell R-19 to Roofline (5") $4,504
Spray Foam Open or Closed Cell R-13 to Exterior Walls $2,926
Spray Foam Open Cell R-13 to Garage Ceiling $780
Sound Proof 1/2" Fiberglass (Under 2nd Floor and Interior Walls R-11 3 Bonus Room Floor) $575
Total: $8,785.00
The HVAC is in the attic, yes. So I know that comes in to play regarding it being operatinig in a conditioned space. I'm confused about why the spray foam guy would spray a roof line of a ventilated attic, but I don't know his job I'm just looking for suggestions on what to do in the situation I'm in. Thanks!
Money tight? Air seal those outside wall and DIY, A Class installation of fiberglass Batts. HVAC system not in yet? Install a horizonal, not a vertical unit, want those ducts as close to the top of the ceiling joist as possible. Main HVAC trunks you want metal for air flow. Drywall ceiling and air seal, Class I job. Spray foam HVAC ducts with 1" close cell foam. Blower door test the heck out of this house and seal those leaks before you blow your insulation. Add R 60 Blow, you can even rent the blower from the big box store. Blower door testing and your free time is your friend. If you do not have time or money that another story.
Brock,
Yes, you are in a pickle. Due to poor planning, you have made several mistakes.
If you have HVAC equipment and ducts in your attic, you shouldn't have a vented attic, in my book. Your only choice is an unvented conditioned attic. If you don't follow my advice, you will be wasting large amounts of energy, as long as you live in your house.
Here is a link to an article with more information on this topic: Creating a Conditioned Attic.
In your climate zone (south Georgia = Climate Zone 2), the 2012 International Residential Code calls for a minimum of R-38 insulation in your ceiling or roof. That is what you should aim for.
Be careful: insulation contractors often lie to customers, telling them that R-20 spray foam can perform as well as R-38. It's not true. For more information on this topic, see It’s OK to Skimp On Insulation, Icynene Says.
Your basic problem seems to be a financial problem: you ran out of money before your construction project was finished. It's time to talk to a banker about getting a bigger loan.