The owner of this little house in North Miami Beach wanted to replace her old tile roof with a standing-seam metal roof. She gets it. More folks down here are catching on to metal roofing’s growing popularity. She also was looking for solutions to a ponding issue – I’ll just go ahead and call it a lake – that affected about half of the addition’s flat roof which wrapped around the original house. This is a typical problem here where the structure was designed dead flat but proved inadequate, sagged in the middle over the years and caused the formation of a massive pond.
There was also the issue of a leak at the transition between the tile roof and flat roof. This problem is all too common and is often caused by the tile setters starting the tile install exactly where the two roof planes meet. This places additional stress at a point which is inherently problematic to begin with. Tile setters are not always roofers so I am vigilant in telling my crews where to start. I prefer anywhere from 6” to 18” above the break to start any steep-slope system as long as it can’t be seen from the ground.
The back side of the flat roof was a lake so we filled it in with 1” perlite insulation and tapered it with 4’ x 12” x 1”- 0” tapered edge. This flat roof now dries completely, well within Miami-Dade 48-hour rule for excessive ponding. The system consists of two hot-mopped Gafglas#75 base sheets with a Ruberoid Mop Granule cap. It is coated with Karnak No. 97 aluminum roof coating to achieve a Class A fire rating. I like this system because it gives the owner a head start on a maintenance regimen, crucial for residential flat roofs, but that is for another article.
