Seattle Insulation Retrofit
Location: Seattle, WA, Marine Zone 4C
Type of Construction: Wood frame single family residence
Year Built: 1947
Size: 690 sq ft main floor, 380 sq ft basement
I purchased a home several years ago that had previously been a rental house for 30+ years and owned by the same family since it was built. It has seen very little in the way of alterations and updates. Which is good and bad. No need to undo poor workmanship but just about everything needs upgrading. Perhaps a blank slate?!
This post is regarding insulation. There is a small amount of loose rock wool in the attic, none in the floor or walls. I am seeking feedback on my idea to create a conditioned attic, insulated walls and unvented crawlspace.
Roof: R-58 (6″ polyiso above framing, R19 batt inside framing)
Walls: R-21.75 (1.5″ polyiso on sheathing, R12 blown in cellulose)
Crawlspace/Basement: R 16.25 (2.5″ polyiso)
I am concerned about putting additional weight on the roof framing (2×4). I will consult a structural engineer, but wanted to float my ideas here first to make sure I am on the right track. Anyone have experience with 2×4 rafters?
I am occupying the home so projects will be competed in phases as budget and time allow. I want to get the details fleshed out before I begin. I have attached a few files showing the existing floor plans, sections and a wall detail with the proposed insulation.
I have learned a tremendous amount from this community and look forward to any insights and recommendations you all might have. Thanks!