What is the best flashing technique for a curb mounted skylight on a flat roof (0.75/12) with existing mineral surfaced rolled roofing? And more specifically, what product is best to make a watertight connection to the existing rolled roofing?
Thanks
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If you're adding a skylight to an existing flat roof I don't think there is any way to prevent a leak with out reroofing
Exactly, you are right.
https://restonroof.com/
I'll take that personally! (haha) However, I'll bet with a quality waterproofing plan, good materials, and detailed oriented installation there will be no leaks. That said, there is a re-roof scheduled in 2 years but we'll get the skylights in first (too many new and old roof penetrations during the phased remodel).
There will be little difference between adding the skylight and new installation. Just remove the roofing, install the curb and flashing. The roof is most likely torch down or hot mop. You may want a slight cricket on the uphill side. The roofer will then reapply new roofing material around the skylight. A roof like this is not dependent on laps to shed water but instead acts as a continuous membrane. The roofing is not a DIY job, however, but should be done by a roofer with hot mop or torch down capabilities.
I hate to answer my own question but clearly, I missed the most elegant and obvious solution...a wonder-product of the 21st century - Flex Seal Spray!
Mike,
I like the cricket idea and I think torch-down is the route to go. However, I will likely install* the skylights and once the remodel is complete the pros can install a continuous membrane.
* I think it's worth the effort given a re-roof will happen within the next 18-24 months and I have 5 to practice on(!). If I can't get the first one right/watertight, then I know my time is better spent elsewhere.
A gallon of roofing mastic should work for 2 years.