Metal roofing in Tampa

Two systems that share a name and little else

"Metal roof" covers two quite different products, and the difference decides almost everything about how the roof will behave in twenty years.

Standing seam

Panels run from ridge to eave and lock together at raised vertical seams. The fixings are concealed clips beneath the seam, so nothing that holds the roof down passes through the weather surface. The panels are also free to move as they expand and contract, which in this climate they will do every single day. It is the more expensive system and the one with fewer things to go wrong.

Exposed fastener

Corrugated or ribbed panels screwed straight through the face into the structure, with a rubber washer under each screw head to seal the hole. Much cheaper, much quicker, entirely reasonable on outbuildings and agricultural structures. On a house, understand what you are buying: a roof with thousands of deliberate holes in it, each sealed by a washer with a finite life.

Why metal suits this climate

• Wind. Continuous interlocked panels with concealed fixings behave well under sustained uplift, and there is no equivalent of the shingle seal strip to fail progressively.
• Water. Long panels with no horizontal joints on typical runs give wind-driven rain far fewer opportunities than a field of overlapping shingles.
• UV. Metal does not have a binder to break down. Coating systems fade and chalk over decades, but that is cosmetic ageing rather than structural failure.
• Service life. Commonly quoted at several decades — substantially longer than asphalt in Florida — which is where the arithmetic starts to favour it for owners who intend to stay.
• Heat. Reflective finishes reduce heat gain into the attic relative to a dark shingle. How much difference that makes to your cooling bill depends on your attic insulation and ventilation more than on the roof colour, so treat confident savings figures with suspicion.

The two objections everyone raises

"Metal roofs are noisy in rain." The noisy metal roof of memory is a bare panel over open purlins with nothing underneath — a barn. A residential metal roof sits on solid decking over underlayment with an insulated attic beneath it. Rain on it is not meaningfully louder than rain on a shingle roof.

"Metal attracts lightning." It does not. Lightning is indifferent to what your roof is made of; height and location decide where it strikes. What metal does do, if struck, is conduct and dissipate the energy rather than igniting, which is not a disadvantage.

Where metal is the wrong answer

Cost is the obvious constraint, but it is not the only one. Some HOAs and some historic districts restrict roof materials and finishes. Complex roofs with many hips, valleys and dormers eat much of standing seam's advantage in labour and flashing detail. And if you intend to sell within a few years, you are paying for service life that the next owner banks. Set against that: a metal roof may affect your insurance rating for the better, though that is a question for your carrier and not a promise anyone here can make.