Metal Roofing Advantages for Long Term Residential and Commercial Protection
Introduction
Choosing metal is the easy half of the decision. The half that decides how the roof looks, what it costs to fit and how it behaves in thirty years of expansion and contraction is the profile — standing seam, corrugated, or pressed tile. They are not interchangeable, and the right one depends more on the pitch and the span than on the budget.
All three profiles are made from broadly the same coated steel, and all three will outlast asphalt. What separates them is how the panels are joined, because that is what determines the minimum pitch they can be laid at, how they handle thermal movement, and how they fail when they eventually do.
Standing seam
Panels are joined by a raised seam that is folded or snapped over concealed clips, so nothing penetrates the weather surface. Those clips let each panel slide as it expands, which is what makes standing seam the right answer on long runs and low pitches — down to about three degrees with the right seam. It is the most expensive to fabricate and the least forgiving of a badly measured roof.
Corrugated and trapezoidal
Face-fastened through the panel into the purlin, with a washer at every fixing. It is quicker and cheaper to lay, it handles an irregular structure well, and it is the standard for agricultural and industrial spans. The trade-off is those fixings: every one is a penetration with a washer that has a shorter life than the panel around it.
- Standing seam: lowest pitch, no penetrations, highest cost
- Corrugated: fastest to fit, tolerant of an uneven structure
- Pressed tile: the profile of tile at a fraction of the weight
- All three: the coating decides the lifespan, not the steel
Stone-coated and pressed tile
Pressed steel tile gives the shadow line of a clay or concrete roof at around a seventh of the weight, which is what makes it the usual choice when a tiled roof has to come off a structure that can no longer carry it. Stone-coated versions add a granular finish that dulls the sound of rain and hail and removes the shine some owners object to.
Making the decision
Start with the pitch. Below about ten degrees, standing seam is effectively the only sound option. Above that, the question becomes what the roof is expected to look like and how long it has to go without maintenance: face-fastened panels want their washers checked every decade or so, and a concealed-clip roof does not.
Whichever profile is specified, the coating and the edge details are what determine whether it reaches its rated life. The steel underneath is the same in all three.
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