Connecting a timber beam for a porch roof to the wall
I will be building a covered deck into the southwest corner of my cabin. The deck will be enclosed on the north side by a 16′ long wall and a 6′ wall on the east side (leaving the south and west sides of the covered deck open). The roof is a simple shed design made out of SIPs that extends past the southern edge of the deck by 3 feet and extends 18″ past the western edge of the deck. In the southwest corner of the deck is a post holding up two timber beams, one running to the northwest corner and one running to the southeast corner (the post itself will run down to the top of a foundation beam).
I’m wondering how to attach the other end of the beams to the northwest and southeast corners? I’ve read that you shouldn’t have large beams extending through the building envelope so I was wondering if it would be better to add a post next to each outer wall corner and then bolt them through the exterior insulation into the wall? In this way the corner posts are providing the necessary support but are thermally isolated from the walls.
Also, could I then just butt the wall cladding up against the edges of the posts to finish off the wall?
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Scott, You could build them as pilasters as you describe, or you could pull them away from the wall by a foot or so and run the cladding behind them.
Just so I'm clear, as there are a couple of Scott Wilsons on GBA. You are the architect from the States who is building a cabin near Nelson?
Yes, but from Canada.
If the additional posts are pulled away from the wall (and therefore not connected to the wall) then essentially the posts are only directly connected to structure at the foundation beam. The top of the post would be connected to the beam which is connected to the SIP panel porch roof.
Also, if the posts are as much as a foot away from the walls then the beam would extend past the top of the post by 1 foot and essentially be just touching the cladding. My concern is that the entire assembly would only be held in place at the top by the screws coming through the SIP panel and into the beam (which would then be attached with screws and brackets to the post top).
Wouldn't it be better to bolt the posts through the exterior insulation and sheathing and into the wall- but how to detail it?
I'd just bolt it as y0u suggested. There shouldn't be enough lateral load to crush the foam. Then butt the siding up to the pilaster. A few GRK RSS structural screws will hold it in place and look fairly unobtrusive.