This insulated flat roof repair in Miami is a great example of what we encounter regularly at Roofer Mike Inc. Ponding issues and elastomeric coatings are also discussed.
We recently completed this insulated flat roof repair in Miami Lakes. The existing flat roof over the Florida Room was leaking close to where the valley of a concrete tile roof spilled on to it. The flat was a modified bitumen BUR over 11/2” of insulation.
We removed two rows of tile at the tie-in and about 5’ up the valley, then opened the modified to reveal some very wet Poly-Iso insulation of which we tore out a 4’X4’ area along with about 10 ‘ of tapered edge at the transition. The amount of water we found was somewhat surprising since the leak was described as small. We soon found out why; there was an old smooth 3-ply fiberglass roof underneath. I was never so happy to see a roof-over in my life! As a result, aside from minimizing the roof leak inside, there was NO rotten wood what-so-ever.
Ponding and Trapped Moisture
We put down a piece of composite board, new tapered edge, 1 ply of Gafglas#75 and ran 3 1/2” screws and plates though it. Next was a layer of Ruberoid Torch Smooth and then Ruberoid Torch Granule. We doubled-up to get flush with the old roof and avoid ponding at the bottom of the valley. Ran the rubber up the valley, nailed down the valley metal and stripped it; then put the tile roof back together with some foam and mortar and we were done, right? Wrong! We installed a 1-way vent as there had to be some trapped moisture.
Also, the tile roof and flat roof were both almost 20 years-old, so while the tile roof could last at least another 10 years, the flat roof’s days were numbered without some serious maintenance. There was some moderate ponding so we applied 2 coats of Somay 814 Rubber solvent-based roof coating and re-enforced the seams with 3” fabric. Done!