Two metal roofs in Miami Springs illustrate how different projects can be though they use the same system. Decking, underlayment and client preferences are discussed.
Metal Roof #1
Before we installed this metal roof in Miami Springs we had to tear off 3600 square feet of concrete tile. They were loose and easy to clean so we were able to salvage over a thousand of them. We made a few bucks doing this and it is better that these tile are sold to roofing contractors for roof repairs than winding up in a landfill.
After tearing off the old roof we replaced the rotten wood and re-nailed the plywood deck to Code. This is the most important part of the job as far as roof integrity is concerned. A metal roof is only as good as the substrate it is attached to. The wood deck must be made secure and irregularities corrected to allow the panels to lay flat.
Homeowner Chooses Underlayment Option
Normally a layer of 30lb felt and then a fire barrier are nailed down before installing metal roofs. In this case the homeowner planned to stay in the house a long time and wanted maximum protection. He chose to also install a layer of Tarco PS200ht underlayment which, while not required here, is great for use on tile roofs as well. In Miami-Dade County the manufacturer specifies the GAF VersaShield fire barrier be done first. Over that the 30lb felt is then mechanically fastened with nails and tin-caps to Code. Tarco PS200 is a self-adhered underlayment, or “peel-and-stick”, and adheres to the 30 lb felt. This triple-layer of protection is as good as it gets.
After all that passed inspection it was time to install an Englert 1101 Galvalume white ¾” standing seam metal roof. The bullnose at the eaves, trim pieces and valleys are all done first and must be professionally installed. They are aesthetically important as well as critical waterproofing components.
The distributor, East Coast Metals, arrived right on time with an Englert-approved fabrication rig in tow. This is what has made metal roofs in Miami more affordable – the ability of local distributors to fabricate panels at the jobsite. We used to go to our regular distributor and order through them from large out-of-town manufacturers. This took weeks. Then some local fabrication shops got their own systems approved by Miami-Dade. With that and the portable rigs the middleman was eliminated and prices went down considerably, almost overnight. East Coast was already an established manufacturer of metal products for all phases of roofing and supplied many local roof distributors. Their shop is really a facility so they were an easy choice for us.
Our excellent installers for metal roofs and they did this job in a little less than a week. Hurricane season was upon us but with a design pressure of 150 PSF the homeowner has few worries.
Metal Roof #2
This second metal roof in Miami Springs was for a customer who wanted to upgrade from shingles – a wise choice. Metal roofs may cost almost twice as much but can last more than twice as long.
We tore off the old shingles and started replacing rotten wood, which was considerable but what was different about this roof was the decking. The house was built in the ‘40s and the deck was sheathed with 1” x 8” pine plank . Also known as straight board, it was used by builders before “tongue and groove” came along and long before plywood. These decks were sometimes referred to as “space board” as they were purposely spaced to prevent them from butting and distorting. As these boards dried out over the years the spaces became wider. Miami-Dade calls for spaces over ¼” to be corrected so we had to change quite a few.
On this job we installed the 30 lb. felt first, tin-capped it to Code and then put down the VersaShield fire barrier. VersaShield only needs to be nailed enough to keep it from blowing away until the metal panels are installed. Later it will be secured by the thousands of screws attaching the panels. No Tarco PS200 here, which is a major upgrade and expensive. The metal panels keep the rain out and the 30 lb. felt is a vapor barrier. Versashield is also water-tight so the deck is protected from any humidity or condensation that might occur.
Inspection time again after which we installed this 1600’sq roof, also an Englert 1101, in a few days. Both homes wound up with the same system but everything else about the jobs was different. No sweat!
Note: These metal roofs in Miami Springs were over five miles from Biscayne Bay. Galvalume is standard for the area and will perform very well. By Code any roof within a half mile of a body of salt water must be upgraded to aluminum, stainless steel or copper.
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