Free-standing porch deck and roof with mineral wool exterior insulation
I’m looking at building a one-story porch with a deck and shed roof connected to a new two-story house with 4″ of mineral wool exterior insulation, 1×4 battens screwed into 2×6 studs 24″ OC , and siding.
I agree with the preference often expressed on this site of not attaching the deck to the house structure, both in terms of water issues and thermal bridging.
My current thinking:
The deck will be supported adjacent to the house with piers that rest on an extension of the house basement footing. The outer edge of the deck will be supported by piers on footings below frost depth. The deck is about 2 feet above grade. The roof load could be carried by posts that are supported by the deck piers below.
The roof ledger or beam adjacent to the house would need to support 100 pounds per linear foot (20 lbs. structure, 80 lbs. snow). The floor system is open web trusses with a 2×4 or 2×6 ribbon board — so no rim board. The porch roof will need to be flashed to the house siding for water control.
Does anyone have a detail for the flashing/connection of a free-standing deck and roof?
The integrity of the roof/siding flashing would seem to require some attachment between the porch roof and house wall.
Lastly, is it reasonable to try to support the porch roof ledger from the house wall (and skip the posts that carry the load to the deck piers)?
Thanks for any responses.
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