Porch addition

[billconner]

I'm in early planning of an addition to our porch - basically a hip coming off a lean-to roof. Long wrap around porch that's too shallow to sit on so an approximate 12 (2 existing posts) x 9 or 10 feet addition off center of a 24' wide porch. Not certain of what solutions for tying new roof to old I haven't thought of, but sort of like this in concept:


I figured I chalk the new valleys and remove all of the shingles on the existing roof at least beyond the valleys, and price and water shield on whole area, trying to slip it as far under remaining shingles as possible. Then frame and sheath addition roof - similar to photo - ice and water down valleys and on new sheathing, galvanized steel "W" flashing, and shingles.

Hope I can reuse removed ones on existing roof side of valley for better color match.

Is there a better or nearly as good but simpler way to do this? I could give up and have all new roof on porch but is not near 10 years old.

Thanks in advance!

 

[nmk_61802]

I can't think of any method that doesn't require stripping back a portion of the existing roof, unless you just add a full second layer.

I think your option is the best most water proof way. A couple of thoughts:

- I know you want the shingles to match, but I would never reuse torn off shingles for anything more than the most minor of patch unless you want to be chasing future leaks.

- I am not a fan of the open valley like you have shown. I think it posses a greater risk of ice damns or back-up leaks as compared to a cut or closed valley.

 

[billconner]

Thank you. You're probably right about shingles - even if using just a few for patching over metal valley as I imagined.

Googling open vs closed, it seems open is overwhelmingly the preferred. From one roofing manufacturer:

"To recap, California valleys and woven valleys may limit the life span of your roof valley. They could even void your limited warranty. When it comes to the question of open metal valley vs. closed valley roofs, IKO’s roofing experts believe that open metal valleys are the better performer. This roof upgrade to an open metal valley gives your roof better resistance to water penetration. Plus, open metal valleys shed debris, snow and ice faster than any roof valley type that uses shingles in the valley."

and a contractor: https://northstarext.com/blogs/open-vs-closed-valley-roof/

I'm curious to your experience of open valleys. I thought the metal was less likely to back up. I know its crucial the chamfer the corners. Always seems like woven or other closed valleys are first part of roof to fail.

PS - I believe it would be a third layer, which I don't want to do. Will look at complete tear off and all new on porch - not many squares.

 

[nmk_61802]

I'm not a professional roofer by any means, but I don't do California or woven, just cut. I still use metal flashing under the cut valley, just flat coil stock, as well as ice and water below that. I then bring the field up past the valley on one side, then cut the other down a straight line. After cutting, I then seal the cut edge.

This gives me three layers of protection and even if the sealant ever fails it is only secondary defense.

In an open valley the sealant is the primary defense, which I never like to rely on.

I get what people say in that the metal will outlast the shingles, however the sealant will fail long before either.

That is my issue.

 

[firebirdparts]

I am the same as above but I don't use sealant. I don't think anybody does around here, but I'm no roofer. Run the first layer past the valley and watch where you put those nails.

As far as stripping the old roof off, you just have to do what you have to do, like any time. I have had good luck (in "life") peeling back shingles to start roofing. If they are "young" and don't break, then it'll be okay. You might be able to pull the nails out easily and not have to cut around the old nails on the first old shingle.

 

[billconner]

Interesting. I did open valleys on my last house - Chicago burbs - and used no sealant. They were a very heavy laminated shingle. Large hip roof with four hip roofed dormers - it felt like all valleys. The overlap of the shingles over the metal, chamfered ends, and no nails near center of valley all seemed to work. Chicago was 8:12, and this one is 5:12. Open valleys may work better at steeper slopes.

 

[ddurrett896]

I'm in early planning of an addition to our porch - basically a hip coming off a lean-to roof. Long wrap around porch that's too shallow to sit on so an approximate 12 (2 existing posts) x 9 or 10 feet addition off center of a 24' wide porch. Not certain of what solutions for tying new roof to old I haven't thought of, but sort of like this in concept:

I did my garage roof like this, connected to the house but didn't strip the shingles. Just framed over them, then shingled. Better than worrying about rain when your in the middle of the project.

 

[Copymutt]

In a similar project. What is meant by chamfered ends on flashing? At top or bottom?

 

[billconner]

In a similar project. What is meant by chamfered ends on flashing? At top or bottom?

In sketch, lower right note "corner of shingle trimmed". Stops water running down valley from being diverted along top edge of shingle.

 

[billconner]

I did my garage roof like this, connected to the house but didn't strip the shingles. Just framed over them, then shingled. Better than worrying about rain when your in the middle of the project.

I don't know how water running down from existing shingles does get under new.

 

[ddurrett896]

I don't know how water running down from existing shingles does get under new.

I'm talking about a rain storm that happens in between stripping the old and sheathing +shingling the new.

 

[billconner]

Understood . I meant existing staying flat under valley instead of turning up on new roof, but maybe you reroofed all.

 

[billconner]

Orch posts now.

Thought about matching wood posts - a lot very very close - but also looked at PVC wraps. Anyone with experience with the wraps?

Second question - skirt - can't stand what's there and some missing/broken anyways - any way I could do stone or block and not have a foundation at frost depth (48")? We haven't liked anything else I've found online. I hope to replace railings as well - with reusing and adding pickets on closer spacing - now 8 1/2 to 9" - probably go to 5 1/2 to 6" (and meet current code 4" sphere rule).