Thursday, September 26, 2013

Torching a Flat Roof With Roofer Mike in Miami

The infamous Miami-Dade tin-cap pattern

Flat roofing project in Miami Springs, FL.
Tear off, dry in & torch - one motion

I was all over this flat roof project in Miami Springs as it posed some serious problems and I wanted to make sure it was done right.

This flat roof had a huge ponding area in the middle of its L shape and also on each of three other connected additions as well. Because there were four separate ponding areas on one flat roof I advised the owner not to attempt correcting them with insulation as the previous roofers had attempted - what a mess. Building up one area only created a problem in another. This called for drastic measures. The additions caused the original flat roof to be the low spot into which they all drained. Therefore, a retrofit drain would be the only real solution. 

Drastic But Simple Roofing System

To achieve 100% positive drainage tapered insulation would have been built up at least 4-5 inches to drain this roof and would have cost the client a fortune. We installed two layers of Gafglas #75 base sheet and torched a ply of GAF Ruberoid torch granule for the cap - a simple, effective and moderately priced base roofing system.

When it quits raining in another couple months we'll install that retrofit drain at the deepest spot and apply a solvent-based Sealoflex application to the whole thing. It'll be fine . .

Update 7/8/2017
Roofer Mike on Flat Roof in Miami Springs
Roofer Mike Staying Sharp!
Sealoflex is a fine system for its price range but the new King of roof coatings is GACO ROOF since it became MDC approved for residential BURs over wood decks. It previously was approved for commercial applications on sprayed polyurethane systems. It is the only elastomeric roof coating to offer a warranty against permanent ponding water. Excessive ponding is defined by Miami-Dade County as any water still standing 48 hours after it rains. BTW, that is a 50-year warranty, people!

Ran into the client for this project and he is pleased. The only thing that made me nervous about this one was the drain. A retrofit in-roof drain requires plumbing to install the PVC pipe in the roof structure and run it out to the roof's edge. I highly suggest the hiring of a plumber for this critical part of an otherwise simple solution to a ponding problem.

Friday, September 13, 2013

Miami Roofers Tarp a Flat Roof

In Miami roofers face a daunting task whenever they must replace a flat roof in the middle of rainy season. Many of these are backyard residential low-slope roofs tied in to a sloped roof - usually a concrete or clay tile roof - creating problems when protecting the home. To avoid a catastrophic flooding of the house during a low-slope replacement we follow these basic steps. Two rules of thumb I’ve picked up over the years when dealing with flat roofs in Miami can be summed up like this: plan ahead and don’t be cheap!!

Pick the right day to tear off the roof. Give yourself the best possible chance to have a day free of the drama that comes with having a flat roof half torn off in the face of a fast-approaching thunderstorm. I simply will not open a roof when rain chances are 40% or more. This is all an exercise in patience not only for you but the customer who should be briefed on the importance of choosing the right day.

Tearing off , drying in & torching - be ready 
Remove roof tiles in advance of the tear-off at the tie-in. Usually we tear off two rows of tile to accommodate the tie-in. When the flat roof is complete we put one row back, ensuring we’ll have enough. This can be time-consuming so it is helpful to have it done in advance.

Make the cut at the tie-in right away. On the morning of the tear-off the cut should be made 18” – 24” above the break at the slope transition. Explore the tie-in area and find where the existing tin-caps are. They are typically installed in rows so if the cut is made immediately above a row there will be plenty of free space to slide in the base sheet for a head-lap of at least 4” or, when necessary, a tarp. Once a flat roof has been significantly torn off there is no choice but to tarp it when a thunderstorm pops up – be ready. Having a phone that will give you real-time animated radar shots is mandatory – you must to be able to see the storm coming.

Tarped flat roof - didn't spill a drop . . .
Use a good tarp – blue won’t do!! When buying a tarp there are basically two rules. RULE 1: DON’T BE CHEAP!! Tarps are color-coded, blue tarps are light duty (5-6 mil) and a too thin to trust here. They puncture easily and that is a disaster on a flat roof full of water. I like the silver tarps. At 12 mils they are heavy duty and UV resistant so you can get more use out of them. RULE 2: DON’T BE CHEAP!! Make sure you buy a tarp big enough to extend over the eaves. The roof shown here was L-shaped so we used two tarps with a 3 foot lap. Placing 2 x 4s under the lap and weighing the tarp down on each side has worked well for me.

I know, the big orange box and roof suppliers have mostly blue tarps and heavy duty tarps are hard to find with a limited selection. has all the tarps you can possibly imagine at great prices with fast and free shipping. With a little planning you can always have the right tarp for the job.

By Michael R. Slattery


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