Added attic insulation & storage platform
Considering adding attic insulation to an existing vented, insulated attic. I will install baffles at the exterior to ensure I don’t block the venting. I know the insulation at the landing access and around the AHU will likely remain compressed (because I’m not rebuilding the systems), and I will add a homemade access hatch seal. If the effort is not extraordinary, it seems worth it to raise the framing for the small storage area to make space for more fluffy stuff. There is very little weight stored there – mostly just extra furnace filters, a few empty boxes that need to be kept, and holiday decorations. The new framing will probably be most of the weight…
What is the recommended method of raising the platform of this storage area? (I know the first response will be to not use the attic for storage – that ship won’t sail, so I’m trying to do it as energy efficiently as possible). Is it as simple as removing the existing plywood, installing new 2×10’s or 2×12’s perpendicular to and over the existing framing (framing of ceiling below/attic floor) at 16″ on center (maybe with a band 2x on either end to keep it from racking?) and then reinstalling the plywood in the opposite direction?
If so, what are the attachment details for the new 2x’s? Is there a Simpson type connector I should use where the new framing sits on top of the existing framing, or should I just screw the new framing into the existing? What type & how many screws? I’ve done numerous searches and don’t see this addressed – looks like most people just compress the insulation down to the thickness of the existing framing…
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Hi CL.
I have seen this done a few ways, not only for a storage platform, but for a catwalk above an insulated attic. But this is an engineering question, so I'm just sharing what I have seem, not making any recommendation.
I have seen platforms framed perpendicular to the attic floor joists and sheathed with plywood as you are suggesting. If your joists can handle this load, I don't think it matters much how you fasten it; you're not building anything structural, more like adding a piece of furniture to the attic floor. If your not putting anything heavy on it, I assume it can be built pretty minimally.
The other way I have seen this done is to run the framing in line with the joists. I guess you could use taller framing lumber sitting next to the existing joists for more height, sister framing onto the existing joists, or stack lumber on top of them. I assume that this option is advantageous when you want to transfer the loads of the additional framing to the load bearing walls where the existing joists land.
I'm sure some GBA members have done this. Hopefully getting your post back to the top of the forum will generate some more responses.