Understanding Different Roofing Materials and Their Long Term Performance
Introduction
There is no best roofing material, only a best one for a given pitch, structure, climate and budget. What follows is what each of the six materials we fit is genuinely good at, what it costs over its life rather than on the day, and the condition under which each of them fails early.
Comparing roofing materials by price per square metre is the quickest way to choose the wrong one. A material's real cost is its price divided by the years it will actually last on your building — and that second number moves a great deal depending on pitch, exposure and how well the structure beneath it is ventilated.
The workhorses
Asphalt shingle is the cheapest way to get a sound roof and the easiest to repair; it wants a pitch above about eighteen degrees and it will not tolerate standing water. Galvanized and zinc-alloy steel cost more, weigh far less, and last two to three times as long, but they need to be free to expand and they must not be put in contact with dissimilar metals.
The long-life options
Clay tile and copper are the two materials that outlast the buildings they are put on. Both are expensive, both are heavy or skilled to fit, and both are effectively maintenance-free once laid. Polycarbonate is the outlier — it is not a roof covering so much as a way of letting daylight through one.
- Asphalt shingle: 20-30 years, cheapest, easiest to repair
- Galvanized steel: 40-60 years, light, needs room to move
- Zinc alloy: 60+ years, self-healing patina, higher cost
- Clay tile: 75+ years, heavy, needs a structure that suits it
- Copper: 100+ years, the most expensive by a distance
- Polycarbonate: 15-25 years, for daylight rather than cover
How each of them fails
Knowing the failure mode is more useful than knowing the rating. Asphalt loses its granules and curls. Steel fails at its fixings and its cut edges long before the panel itself goes. Clay spalls where water has frozen inside it. Copper essentially does not fail, but the fixings and the timber beneath it will. Polycarbonate yellows and goes brittle under ultraviolet.
Matching material to building
Start with what the structure can carry and what pitch it gives you; those two constraints eliminate most of the list before budget is discussed. Then ask how long the building is expected to stand and how accessible the roof will be. A material that needs looking at every decade is a poor choice on something four storeys up with no permanent access.
We stock all six and we fit all six. Which one we recommend depends entirely on the roof in front of us.
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