Fasten (new addition) roof sheathing under existing overhang

[StephenP]

Haven't started the project, yet - just trying to noodle through some things beforehand...
I plan to lower the roof line on the addition just enough to fit under the existing overhang (it's a simple gable), but how do I get under it to fasten the sheathing? Does it even need to be fastened under there?
I'll try and attach a 'before' pic.
Thanks.

S..

[dhill]

Why lower it? Why not just attach to what's already there?

[StephenP]

The addition will sit on a slab that will end up about a foot lower than the house, which sits on piers. The way I see it, (and I don't assume by any means that I have thought of everything), if I wanted to match up the roof lines, I would either have to have the trusses built such that they would sit that much higher than the (new) walls, or build a short wall to make up the space between the trusses and the (new) 8-ft. wall, or use longer studs - all of which would require scabbing in pieces of exterior sheeting to make up for the difference in height, and similar for sheetrock inside. Besides, I think having the roof line broken up might be more interesting to look at.

I hope that makes sense. Thanks for the reply! :D

S..

[dhill]

Okay, but think about this. If you lower that roof line, you're going to have to do a heck of a lot of construction to keep that roof from leaking where the new roof connects to the old house. I'm not saying it can't be done, but .... It's a whole lot easier to simply drop your ceiling down that extra foot inside the room than it is to drop that roof down, imo. Or use a 9 foot ceiling in the add on room. The difference in price between an 8 foot 2x and a 10 foot 2x isn't likely to break the bank. What kind of siding do you have on the existing structure? Are you planning on matching it? There's lots of ways to gain the extra height for the siding and the inside sheet rock isn't any big deal. Anyway, just some thoughts. You certainly can add the new roof directly under the old one. Just attach the first truss to the side of the house, butt the decking against that side, nail in at an angle on that truss if you need to. Be sure to use flashing (you may have to re-do some siding, not sure how you plan to do that part.)

Dusty

[VALENT]

Idefinitely would give a lot of thought to what DHill has posted. Plus, it is almosts always better for an addition to be unnoticeable in as many regards as possible.

[StephenP]

We did try and envision how it would look in relation to the rest of the house when complete. I don't like the look of an obvious room addition. In this case, we thought that as long as we kept the same siding, trim, etc. - it might look better with the roof line broken up a little. (Maybe even less noticeable). Maybe if I hadn't ordered the lumber, I would re-think that decision, but I think it'll work. As far as siding, the house is covered in white-painted redwood boards, but I plan to stucco everything later.
I might take a piece of flashing, maybe a foot wide or so, bend it at 90 degrees along it's length, and slip it under and against the existing fascia. Then if I cover the remaining half of the flashing as I nail on the shingles, shouldn't that make a sufficient seam?

Thanks.

S..

[VALENT]

It will work. I think you have a good flashing plan. Otherwise, you can use step flashing with each row of the shingles. (or both-probably not needed)

[dhill]

I've seen many houses with a roof line broken like you're talking about. They look just fine. I think you're ready to sail that ship.

[Sweep]

Speaking from my experience designing houses, I think you should build a 9 ft high space and align the roofs, although I don't know how you plan to use the additon so I may be off base. I think the exterior look of this house will be determined more by your window selection/placement and stucco detailing/color than a small 12" drop in the roof which, to me, is a sure sign of an addition. I would negotiate with the lumber supplier for taller wall framing (i.e. beg).

But since that is probably no longer an option, I want to say something about the roof connection detailing. dhill was right when he said, "you're going to have to do a heck of a lot of construction to keep that roof from leaking where the new roof connects to the old house." Because the roofs are so close together there is not enough room to connect the new roof to the face of the old wall so you must connect at the face of the rake overhang or remove the overhang and connect to the face of the old house. Both options are a lot of work and have the potential to look awkward.

Removing the rake overhang is probably the best option but if you connect at the face of the rake overhang, it is important to build it the same way you would build against the old wall. Remove the rake trim and physically connect the roofs vertically, add sheathing, apply Ice & Water Shield, install step flashing as each row of the shingles are installed, and reapply the facia leaving at least 3" of flashing showing. It is VERY important for the appearance of the house to use black or dark brown aluminum or copper to crete a visual separation between the rake trim and the new roof. The facia should probably be a synthetic material that doesn't have to be painted because it will deteriorate quickly from rain splashback and is difficult to paint without getting paint on the roof.

Whatever method you use, at the bottom of the roof connection, the new roof eve should ovelap the old wall and the new flashing should turn the corner and extend that same distance either at the face of the wall or just behind the eave trim (potentially awkward detail that needs to be drawn or mocked-up in the field).

If you get tired of this roof detail and are still stuck with the framing delivery you could build a perimeter foundation wall and frame a floor over a crawl space; use the lumber you have; align the roofs; and avoid a big step-down in your house, a very hard floor and the feeling that it might be a coverted garage (yes, I grew up with one). The money you save on the roof detailing would defray some of the extra foundation/floor cost. I avoid stepdowns since most of my clients believe they or a relative might someday need a barrier free design (not to mention resale value.) Or maybe I'm just getting old.

As you can tell, I can't resist redesigning a project, even AFTER it's built. Good luck, hope you are pleased the finished project.

[VALENT]

Sweep, lots of good thoughts there.
StephenP, you have to do what you want or you will always wonder but pay attention to that flashing.

[StephenP]

Speaking from my experience designing houses,...

Wow - lots of good info! I will be coming back to this forum (and this post in particular), when I get that far - no matter which way I go with it. Thanks a ton :D !

S..

[StephenP]

Well - I've given this some more thought, and now I'm thinking seriously about going with 9ft. studs and match up the rooflines. I'll use the 8ft. studs I've already bought for another project. I agree with the points made above, and would rather have 9ft. ceilings anyway. Thanks for all the great info!

S..