Patio roof to house attachment question

[MikeInMobile,AL]

Hello. Great site with lots of great info.

I am an amateur carpenter with some experience in framing, decks, and roofing.

I am planning to install a 10' x 32' back patio cover on my house. It will have 4x4 uprights, 2x6 header, 2x8 ledger, 2x6 frame, and a preferably a tin roof.

I am pondering how to attach it to the house. The house has a hip roof. The lower edge of the facia board at the house is 7' from the slab.

Option 1 and the one I prefer is pulling off the facia board, installing a 2x8 ledger board using one 3/8 x 6" lag bolt through the ledger and into the ends of each of the house rafter boards. I would then butt the 2x6 patio rafters into the ledger with joist hangers. I would also butt the patio rafters into the 2x6 header at the outside end of the patio with joist hangers. This would give me 7' of headroom at the the house, and 6'6" of headroom at the outside end if I drop the roof 6" for runoff.

The small bump in areas where the roof line is recessed would be framed in behind the ledger and plywood and shingles will cover them, extending the existing shingled house roof to the ledger.

I would tar paper over the joint where the ledger meets the house, and then use flashing under the last row of house shingles and extend the flashing either 12" or 18" out over the patio tin roof.

We get quite a bit of rain here, but no snow.

I realize other option is going up and tieing into the house roof, using plywood sheathing, tar paper and then shingle the patio roof.

I would rather use the tin roof option. In your collective experienced opinions, is my plan workable or is it a complete mess?

Do you have any suggestions

Thanks for any help.
Mike

[Don_P]

The rafter tails are not a point of support.
The minimum roof slope is 3/12, you might get away with 2/12 with metal but since in either case I'd put the pitch break over the house I would go with a minimum of 4/12. If that is 10' out from the wall then the roof would need to be up 40" above the starting elevation by the time it crosses the wall. It will intercept well up on the roof.

If you must stay off the roof, remove the fascia and slide the porch rafters in alongside the house rafters until they are over the wall. Then when the connections fail it is over support. Your plan #1 drops the roof on someones head when the connections fail. Nail the new rafters to the existing house rafters well. The low pitch and flash option is going to back up water and cause rot when it backs under the shingles.

Notch the treated header into the post so it is bearing on wood. The bottom of an appropriate sized header should not be less than 7' above grade and should really be above window top level. Another reason to put this up on the roof. I wouldn't use less than a good SYP 2x8 with no snow load on that 8' header span.