How tile breaks
A concrete tile is strong in the direction the weather comes from and weak under a point load at its unsupported edge. The nose - the lower, exposed lip of each tile - sits over a gap. Step on the nose and it snaps. Step on the crown of a barrel tile and it can crack along its length. Step where the tile is supported, at the top of the lap, and it usually holds.
Which means every step on a tile roof is a small decision, and most people going up to "have a look" do not know they are making it.
Who breaks tile
In our experience, in rough order: pressure-washing crews, satellite and solar installers, air-conditioning technicians, painters, and homeowners. Roofers break tile too - it is not possible to work on a tile roof and never crack one - but a roofer knows where to step, carries replacement tile, and puts it right before leaving.
Why it matters more than one broken tile
Cracked tile often stays in place looking fine, with a hairline fracture that lets sun reach the membrane underneath. A roof that has had a non-roofer on it may have several of those, none visible from the ground, all quietly ageing the underlayment.
If someone has to go up
- Step at the top of the lap, where one tile overlaps the next and is supported, never on the nose.
- On barrel tile, step in the valley between barrels, not on the crown.
- Spread weight; move slowly; do not turn on a single foot.
- Assume something broke, and have the roof checked afterwards.
The better answer
Do not go up. If you need to know what is happening on your tile roof, a drone or a roofer will tell you without adding to the problem. And after anybody else has been on it for any reason, have it looked at - that is one of the standing reasons for an inspection.
Roof Sentry members get a post-work check whenever another trade has been on the roof - because that is exactly when tile gets broken.
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