Breezeway roof connection?

[Matt_inthehills]

Hi Guys and Gals,

I have a question regarding an ADU that I'm modeling. The client wants a breezeway, but does not want walls, or posts to support it. It will be connecting the ADU to the existing house.

Supporting the ADU side of the breezeway is easy. The walls will be new, and bearing the ridge, or beams down to the footings isn't an issue.
The trickier part is finding a simple solution to support the house side.

Would it be best to design the side beams that the rafters sit on large enough to support the span (12' clear from adu to house), and open up the walls of the house to add studs to bear down on. Then use a non structural ridge board to support the top. Or, is there a way to do this without opening the house walls up. Perhaps with a larger ridge beam to support the load, and have it bear on the existing roof, ideally on top of a truss, then smaller beams on the sides that could possible tie in to the subfascia board of the house?

Thanks!

Here's a picture for context...

 

[jayrod12]

house is on the left?

I'd be putting ttwo edge beams with posts inside the wall, and then do it with trusses, even site-fabbed trusses with plywood gussests over just stick built roof framing.

 

[Matt_inthehills]

jayrod12 (Structural)16 Mar 22 19:44
house is on the left?

I'd be putting ttwo edge beams with posts inside the wall, and then do it with trusses, even site-fabbed trusses with plywood gussests over just stick built roof framing.]

Thanks for the response, and yes, the house is on the left. I like that idea, it's what I've been leaning towards in my head as well. If it were my place, I would open up the walls of the house to add posts for the beams to bear on, and deal with the small amount of siding to repair after. This way, you don't have to count on the existing house roof to support much of the weight.

 

[jayrod12]

If you've got a really good drywaller, may be simpler to remove drywall on the inside to set the posts. Then on the outside just make tight cuts in the siding to allow beam install and then caulk around the joint.

 

[Matt_inthehills]

That's a good point, it would be easier to do from the inside. Just one layer of drywall vs sheathing, building paper, and siding to repair after. You could even tuck up some "L" flashing in the top cut before installing the beams.

 

[HouseBoy]

I'm with JR. Drywall repair will usually be MUCH less obvious PLUS, messing with the existing building envelop could be a pain. (Although if the existing house is older, that envelope might not be too much to begin with.
Really, expect for a very heavy snow load requirement (not sure about your location) the loads shouldn't be great. Maybe adding a stud or two in the wall should be the most that would be needed. Details will depend on exact height of beams and existing wall plate. You'll need to strip off the shingles and over-frame onto the existing roof and flash the valleys but that's a common task.

 

[Ron247]

Can you run the rafters let to right? Install them plumb but miter top for roof decking. How long is the span? You could put a nailer on the right gable and a stub wall over the left wall at eave.

 

[Matt_inthehills]

Ron247 (Structural)16 Mar 22 20:20
Can you run the rafters let to right? Install them plumb but miter top for roof decking. How long is the span? You could put a nailer on the right gable and a stub wall over the left wall at eave.]

It's 12' from wall to wall, and just under 19' at the ridge. I think I understand what you're saying... Run the rafters parallel with the ridge (plumb for strength) and rip a bevel in the tops for the roof pitch. Essentially, each rafter would be acting as it's own beam, tied together by the sheathing.

For the stub wall, do you mean build it over the existing wall plate, or on top of the trusses?

HouseBoy (Structural)
Really, expect for a very heavy snow load requirement (not sure about your location) the loads shouldn't be great.]

The location is in Southern Nevada, at a low elevation, so no snow load.

 

[phamENG]

Yeah...I'd do beams at the eaves and do the work from the inside. You will need to do some work on the exterior as you'll be messing with the building envelope anyway and flashing those beam penetrations properly will be critical. Probably don't need trusses....stick built roof with rafter ties and collar ties would be easy and, depending on your market, can be built tomorrow while the trusses might have a 6 month lead time.

 

[dhengr]

Matt_inthehills:
Over the house, over-frame the new roof. That is, a ridge board and rafters down onto 2x8's or 2x10's which rest on the existing roof sheathing and follow the new valley line. At the ext. wall of the house, open up the house roof sheathing at the interior plane of the studs and build a new (gable shaped?) wall on top of the existing double top pls. Maybe this should top out a few inches below the new roof plane or it will be a hard spot/line alongside flexing rafters and it’ll show up in the roof plane, but sheath it both side with plywd., so it acts as a deep box beam distributing the new roof loads to all of the existing ext. wall studs. You must study and detail around exist. truss top chords and door and window openings in the wall to do this, but it is unlikely that that ext. wall is overloaded at the outset. But, this keeps you out o f that ext. wall altogether. Then, on the new roof, you might have enough depth for eave beams 16" or 24" in from the fascia. They could hang down and be dividers btwn. the eave soffits and the ceiling of the breezeway. The eave beams and ridge beam frame into your new box beam wall for distrib. into the existing ext. stud wall. This roof space must be properly flashed and vented. Framing onto the new wall should be pretty straightforward, onto posts in the new wall.

 

[Ron247]

Yes, I mean build the stub wall over the exterior wall at eave; it keeps your rafter length the same.

 

[Matt_inthehills]

Thanks for all of the ideas everyone!

I presented some of the options to my client, and since he is doing the framing himself, and he's not a framer, he chickened out on opening up his walls, or roof. We have decided to go with posts under the eave beams for most of the support, site-fabbed trusses, and standard over-framing onto the existing roof. As well as the posts, the beams will also bear down onto doubled up studs in the ADU wall. I preferred the clean look of no posts, but ultimately, it's the client's decision.