Help me plan a new roof that maximizes energy rebates
I’ve got a 1960 SoCal Ranch house with 3 layers of roof that has to go. It’s about a 3.5 or 4 pitch, with 2×6 rafters 24″ OC. It’s currently vented at the gables and some soffit venting. I’d like to use the tax incentives in 2010 for both reflective roof materials and for insulation. Do to the specifics of this house (penetrations, can lights, Duct in attic) I’d like to move the insulation layer from the attic floor to the rafters and deck. *I’m a little confused about my specific building climate. On the National map, SoCal is in Zone 3. On the California Climate Building Zones map, I’m in Zone 8. I’m trying to figure out what exactly that means as far as how much attic insulation I need.* EDIT A: R30 + Radiant Barrier I’m looking for ideas here. Starting with bare rafters, how might you insulate this, and what Energy Star covering might you use? I had initially thought about using the GAF Royal Sovereign White 25 year 3 tab shingles, but I hear shingles have risen dramaticly in price – perhaps metal is closer in price now?
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I have a little new info here, to at least answer my own question of insulation.
According to these rules:
http://www.energy.ca.gov/2005publications/CEC-400-2005-005/chapters_4q/3_Building_Envelope.pdf
I need as a minimum R-30 AND a radiant barrier (foil faced OSB deck with air space for example)
Unless you can install the radiant decking on sleepers on top of the existing sheathing, I can't see how it would be worth it to rip up the entire roof. The other thing to think about is you actual tax paid. If you don't currently have a tax liability or a very low one, you may get limited tax credit anyway since this is not a refundable credit to my knowledge. I'm not even sure you can carry it forward since I haven't seen the rules yet.
The problem in your case is going to be 2x6 on 24" isn't very sturdy for laying sleepers and another deck, at least it would seem to be but it might actually weigh less than three layers of asphalt.
Have fun tearing that off by the way.
The existing deck is big knotted 1x6. I could leave it, but taking it up gives me alot more room to work from the top rather than trying to fit into the low attic.
My thinking at the moment is to sheath the underside of the rafters with OSB or drywall so I can blow in cellolose, then add 2" of foil faced Polyurathane rigid foam to the top of the rafters. There would be 2" horizontal sleepers of ripped 2x4, then a vertical sleeper layer over the foam (the other half of that rip cut). The top layer would be a sheathing of foil faced OSB with synthetic underlayment over that then whatever roofin material.
I'm only adding that radient layer due to the Cali specs calling for it, otherwise I would just make it a straight hot roof.
Have you considered 6" Structural Insulated Panels to lay over your existing roof deck? I had a similar question as yours about a year ago and received wonderful feedback from Breaktime. Depending on the complexity of your roof, this could be the easiest, less labor and hassel than your idea mentioned here. Yes, you can remove your existing 1X decking with the SIP option, but not necessary. Obviously, with the SIP's, new facias will be required due to new roof thickness.
Right now I'm wondering about
Right now I'm wondering about roof coverings - specificly Energy Star rated materials. Anybody have any favorites - or ones to stay away from?
If i were you and being down here in socal I would look at solar panels on the roof also if your roof allows. Why not save some on the electric bill along with getting the tax credits that come with it. Especailly if you are putting down a new roof. you know you shouldn't have any problems for awhile.
That's not a bad idea, but
That's not a bad idea, but I'm not sure we could swing the bucks out of pocket on that. I suppose I could look at an outfit that would lease them to us.
I could at least mount the racks up there in preparation. Better to do that then than as a retrofit.
Paul -
I've had numerous
Paul -
I've had numerous customers ask the same questions. There's a fine line between going for a high tech (translated "high cash outlay") solution to harvest tax incentives and going the low tech/low cash route.
The roof is an important architectural feature and can make a big difference in the curb appeal of the house. No matter what material is used, a white roof is not gonna stay white.
I would seriously consider a metal roof or new shingle roof on the existing framing/sheathing after tearing off. While the roof is torn off, pull sheathing boards as needed to access the attic to blow cellulose. Fill the attic up.
Look into metal roofing. The manufacturers seem to be pretty vague about whether their products will qualify for the rebates or not. They want you to do the footwork. I've seen some products that do qualify on the web, but they are not available in my area.
If you follow the links on the Energy Star/Federal Tax Rebate websites they have a list of approved products. Mostly metal roofs.
But there are some shingles that are approved. But they are only available in SoCal.
There must be some Cal rules and/or rebates that favor them. They don't seem to be available in the Texas or FL areas where I think that they would be useful.
seeyou: Blowing cells is certainly the easiest and cheapest option, but I've still go alot of work to do in this house, including ceiling work.
CosmicCow: Thanks for reminding me of SIPS. I have to find a local supplier and hit them up for some prices.
That also reminds me of the recent R40 wall article, and about the different techniques they used... Larsen roof anyone? You could always pull the ridge cap to make sure you got a good densepack!
Looking at the R40 wall article
Blowing cells is certainly the easiest and cheapest option, but I've still go a lot of work to do in this house, including ceiling work.
Just to keep cells as an option.... some pre-planning for attic access can still make cells attractive and get the insulation tax credits.
It is easy and inexpensive to create a raised cat-walk platform down the middle of the attic. I made one out of 2x3 for the frame. For the platform I used heavy duty metal grocery store shelves (free). Plywood/osb works. 18" wide works fine. Wider if you need it.
With the platform/catwalk, you can blow cells under it. Some even raise up attic hvac mechanical so that cells can be put under. Make drywall boxes to surround high-hats.
I left my existing old drywall on the ceiling and strapped over it, hung new drywall. This way I could get the new cells installed sooner w/o having to wait to remove and replace the ceiling drywall.
I've actually got a wire
I've actually got a wire raceway going over the collar ties now that is the central nervous system of the house. All the electric runs through there now, and after i run conduit I'll run data through there too. The underside of the collars is about 24" off the top of the joists... not enough room for a catwalk.
Questions about metal roof coverings: Can you walk on them - or does it turn into crumpled foil when you step on them?
Also - Does fungus grow on north metal exposures like it does on shingles?
OK, here is the detail for the insulation layer...
anything I'm missing here?