Lowered ceiling joists for more vented attic insulation.
Chris8topher
| Posted in General Questions on
I was playing with the idea of doing 9′ walls on the second floor and then hanging the ceiling joists on the walls down to the 8′ level. In essence just adding a foot for insulation space.
This would be for a hand cut roof.
Is this a thing or does this significantly weaken the roof structure too much?
I was hoping to accomplish something similar to a raised heel that allows more insulation closer to the exterior walls.
I was thinking this would also let me put the headers in the ‘attic’ wall space, reducing thermal bridging in the walls.
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Replies
Christopher,
Should work well. It can make air-sealing between the house and attic a bit more complex. Structurally the roof is similar to a cathedral ceiling, with the slight added benefit the dropped ceiling brings. Unlike what's shown on your section, the rafter ties need to be located in the bottom third of their span.
Thanks, I'll keep those in mind if I decide to go this route.
Christopher,
I really like the attic headers idea.
A common detail with older houses around me is to extend the ceiling joists past the walls to form the soffit. The rafters can now be set to sit at the end of the joists and you use a piece of 2x lumber on edge ripped to height above the wall to carry the vertical down directly.
This raises the rafters up a fair bit and gives plenty of insulation space at the walls. It is actually simpler to build as you don't have to cut the birds mouth notches on each rafter and you have the soffit framed up for free. You will need longer rafter tiedowns though, but that is a simple change.