Yes exactly, at 45 degrees. It feels like an industrial floor, like an old car dealership.A subfloor of old growth 2x8s laid flat, I’m guessing diagonally for shear. From your description, you could park an Abrams tank in your attic. Slight exaggeration but you get the idea. Do you care if the storage space is conditioned? Because my inclination is to insulate and air seal between the attic floor joists and let the whole attic be ventilated.By full attic I just meant the entire upper floor is a stair accessible flat floored storage area with exposed rafters and roof over it. At crest the attics ceiling is 10’ high. I’m sorry I didn’t know full attic means something special. There might be insulation under the attic floor but I’ve never seen it. Attic floor boards are gorgeous old full size 2x8, joists are under there but I’ve never seen them. Attic floor feels very solid. I’m not sure what mistake I may have made with my description.
The rafters in the attic are quite close to full size 2x4, there are fiberglass batts sloppily stapled into place between them. Rafters are approx 16’ long with a knee brace. Above the rafters is a lath, I think for the original shingles? Is lath the wrong word? I’m not sure the plywood is 3/8 or 1/2”, looked like 3/8”. A cheap reroof in the 70s, new composite shingles in the 90s. I move like a cat and it flexy to me when I’m up on the roof.
I believe roof survives because it’s quite ventilated and poorly insulated. Hot in summer and cold in the winter. I sealed the area with more insulation between the bottom ends of the fiberglass and the floor, crawled way back almost into the soffits but there’s still air getting in through soffit vents to the fiberglass’ uncoated side. Behind insulation is not air tight and neither are the batts, but they are dry.
Weight: I just added up the weight of insulation for 1350sqft of roof surface, new plywood weight and the weight of 2x12 to go over existing rafters. Like a preschooler with a crayon and a spreadsheet. Just guessing to cost materials because the right person knows the right way to do this and what data we need to decide what is feasible.
I spoke with an ‘as built’ plan scanning company today. They don’t do the colonoscopy either. His advice is to first find an engineer I like and do what they say, and that if we hired him he’d be happy to speak with the engineer to get them what they needed.
I can scan a house into a plan, I did the basement for earthquake retrofit permit. what I can’t do is tell what’s behind the walls on main floor. I figured this was a thing but seems like it’s not. Starting to realize that house structure below the roof is probably way more than fine unless there is serious compromise somewhere, engineers I spoke with seemed mainly worried about any removed walls or foundation damage (good there.) It could be my house strength concerns are not serious to professionals? I don’t know.
Main floor interior is plaster on lath and it’s all still perfect with mahogany trim and original art deco fixtures. The guy that first lived in the house built every house on this side of the street.
I’ve wasted a bunch of peoples time with this, probably I’m approaching this wrong or just unlucky with who I’m talking to. I think the right person is out there. I had the same problem trying to get my cars suspension redone- no progress for months and then everything happened instantly and affordably once I found the right person. In this case I suspect the right person specializes in exactly this and can give me the go/no go advice in 2 seconds.
I’m waiting to hear back from some local structural engineers.
I would love (love, love, love) to drink beers with building science people. I assumed that website was the baby steps into the modern construction world (many of their papers are over a decade old) but so far no one’s even heard of it. Architect I talked to got angry at me because he was convinced I should fill the pretty rafters with spray foam, and yeah sorry I’m not going to do that I’d rather freeze.
I’ll try to specifically look up building science people, great idea. I didn’t know even building science was a subset of builders. some sort of cult? Can I join?
Edit: oh gosh:
https://www.thebsandbeershow.com/
Uninsulated attic: hmm. Is there space for sufficient insulation to prevent condensation at the bottom? Would the space between joists be encapsulated? Isn’t there major heat loss through joists?
Maybe being dumb but I can just imagine that someday it could be an extra living space. Quiet with great view of the sound and mountains from the windows on the ends.
Statistics: Posted by eri — Tue Feb 18, 2025 12:49 am — Replies 15 — Views 1065