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This seems a common enough situation, but i haven’t been able to find a discussion, even after searching TFA: I have a 1940’s house with 2×4 walls to which i’m adding a layer of 1 1/2″ foam over felt before i re-side with Hardieplank. It was moved onto a 2×6 treated wood, insulated foundation whose 4″ slab has a moisture barrier and two inches of foam under it, which will be wood-heated for my woodshop–approx 1440 sq. feet each floor. There will be a garage door for this walkout basement, sealed off during the winter. The uninsulated ceiling is framed with 2×10’s on 16″ centers.
On the first floor, i will use primarily wood heat, with propane direct-vent heaters for backup. At this point, ceilings in kitchen and bath are exposed; other ceilings/walls are tight plaster. Ceiling joists are 2×8’s 16″ O.C. No moisture barrier or insulation. Hip roof is 4.5:12 pitch, framed with 2×6’s 24″ O.C. Asphalt shingles over board sheathing in good shape. Making new windows and doors, insulated glass.
The question is: how to insulate to retain the use of the attic and its limited headroom? I am thinking of insulating the ceiling joists AND the rafters, splitting my r-values without losing height, realizing the attic won’t be as temperate as the main body of the house, more of a buffer zone. Have read the dense-pack v. FG stuff, but still don’t know what to think about condensation in this case, because there are attic pull-down stairs: though i can tighten up their closure, they will be open while i’m up top–will this be a significant source of moisture from main body of house, which is not that tight to start? I have drilled the hip rafters for venting and installed ridge vent, was planning 3 1/2″ FG to leave room for air flow, but the extra R’s of not going with a cold roof would be welcome in Montana winter. Any non-thermally conductive material to sheet the underside of the rafters that would stand up to dense pack if i go that way? Dense pack in the ceiling joists under ply? Could i just plumb fill the area behind the kneewalls?
A gadzillion thanks for opinions, ideas, and/or directions to other sites.
Replies
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This seems a common enough situation, but i haven't been able to find a discussion, even after searching TFA: I have a 1940's house with 2x4 walls to which i'm adding a layer of 1 1/2" foam over felt before i re-side with Hardieplank. It was moved onto a 2x6 treated wood, insulated foundation whose 4" slab has a moisture barrier and two inches of foam under it, which will be wood-heated for my woodshop--approx 1440 sq. feet each floor. There will be a garage door for this walkout basement, sealed off during the winter. The uninsulated ceiling is framed with 2x10's on 16" centers.
On the first floor, i will use primarily wood heat, with propane direct-vent heaters for backup. At this point, ceilings in kitchen and bath are exposed; other ceilings/walls are tight plaster. Ceiling joists are 2x8's 16" O.C. No moisture barrier or insulation. Hip roof is 4.5:12 pitch, framed with 2x6's 24" O.C. Asphalt shingles over board sheathing in good shape. Making new windows and doors, insulated glass.
The question is: how to insulate to retain the use of the attic and its limited headroom? I am thinking of insulating the ceiling joists AND the rafters, splitting my r-values without losing height, realizing the attic won't be as temperate as the main body of the house, more of a buffer zone. Have read the dense-pack v. FG stuff, but still don't know what to think about condensation in this case, because there are attic pull-down stairs: though i can tighten up their closure, they will be open while i'm up top--will this be a significant source of moisture from main body of house, which is not that tight to start? I have drilled the hip rafters for venting and installed ridge vent, was planning 3 1/2" FG to leave room for air flow, but the extra R's of not going with a cold roof would be welcome in Montana winter. Any non-thermally conductive material to sheet the underside of the rafters that would stand up to dense pack if i go that way? Dense pack in the ceiling joists under ply? Could i just plumb fill the area behind the kneewalls?
A gadzillion thanks for opinions, ideas, and/or directions to other sites.