New roofing meeting old – how to join?
I’m reroofing part of my house (garage and new crickets) and making a repair to another valley. The old roof is three layers deep – top is good 10 y.o. asphalt shingle, 2nd is old badly deteriorated shingle, bottom is asphalt on paper with gravel embedded. Home was built in 1960.
A second story addition caused the need for new runoff routing. It was built on about a 1 in 12 pitch with roll roofing. The way it was built wasn’t vary good, so I built crickets to channel the major water flows, and am repairing another section. Where the old roof meets the new plywood is where I have my question. This new plywood is over the 1 in 12 pitch valley. I am putting a 24″ metal W valley in where the shingles meet the flatter roof. The plywood will be covered with underlayment (Ice Shield and Titanium UDF), then 75lb felt cap nailed down, then covered with Henrys (don’t remember the number, it bonds to roll roofing), then covered by the white rolled asphalt roofing.
Here is a diagram of how I think it should go together. I was wondering if there are other approaches I should look at in this case?
Rebuilding my home in Cypress, CA
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If possible, I'd get the valley below all the layers of old roofing. That way, when the inevitable happens and you have to replace the other side, you don't have to dig out the roofing under one side of the valley.
Birth, school, work, death.....................
Nice! I hadn't thought of that. However, when I do redo that roof I'll likely be making a bunch of changes. I'll at least built out a steeper valley there to flow the water off faster, plus I may even change the covering type so everything would come off again anyway. BUT... if and when that happens is another thing.
If I did put those other three layers ON TOP of the valley metal, I would have to seal each layer shut with the other ones to keep water from wicking back up. I plan on using a Polyurathane flashing caulk for this... any better ideas?Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If I did put those other three layers ON TOP of the valley metal, I would have to seal each layer shut with the other ones to keep water from wicking back up. I plan on using a Polyurathane flashing caulk for this... any better ideas?
Just dig the bottom courses of the two bottom layers out and reshingle the lower part of the top layer. There'll be a bump, but in the direction of the flow. I don't see any reason for any caulk on the steep side of the valley.Birth, school, work, death.....................
Ahhh, yes, now I see what you mean. That does sound like the best bet - thanks!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
It is hard to believe that shingles can do the job for a 1in12 roof, but maybe we are misunderstanding the situation.
In any event, if I was doing this job for a customer, I would insist that we do the whole job at once. For a temporary solution you can do almost anything but it may leak. Why do a permanent solution twice?
The original roof is at 3.5 in 12, but the plywood is on only a 1 in 12 slope. The shingles are on the steep side, roll roofing on the shallow.
Normally, I would agree with you. However I will be taking off the original roof deck and replacing it with radient barrier deck when I redo that portion. The garage and valley sections I'm doing now are the most complex portions and have been time consuming for this DIYer. I have neither the time nor the budget to finish the roof as I will eventually want it to be... at least not yet.Rebuilding my home in Cypress, CA
Also a CRX fanatic!