Cracked Or Slipped Tiles: What To Do And What Not To

What a broken tile actually does

On a foam-set tile roof the tile sheds water and takes the sun. The waterproofing is the self-adhered underlayment beneath it. A cracked, slipped or missing tile does not by itself let water into the house - the membrane is still there. What it does is expose that membrane to direct ultraviolet, and membranes are built to live in the dark. Exposed, they age in months what they would otherwise age in years.

So a broken tile is not an emergency. It is a small area of your roof ageing on a much faster clock, and the sooner it is covered again, the less of that clock runs.

What not to do

• Do not walk the roof to look at it. Tile cracks underfoot, especially older tile and especially at the nose. The most common way a roof acquires three broken tiles is someone going up to look at one.
• Do not caulk it. A bead of sealant across a crack does nothing for the UV exposure and makes the tile harder to replace cleanly.
• Do not let a non-roofer "just pop one in". A replacement tile has to be set in the same way as its neighbours or it becomes the next one to slip.

What replacement involves

The broken piece comes out, the membrane underneath is checked for damage, and a matching tile is set in foam adhesive. On accessible, readily available standard concrete or clay profiles this is routine, and both Roof Sentry plans carry an annual allowance for it: up to ten standard broken tiles a year on Baseline, up to twenty in total on Storm Ready. The "standard" and "accessible" words are doing work in that sentence - see below.

When it is not routine

Discontinued profiles, unusual colours, and tile that has to be sourced from a salvage yard or a specialty supplier are quoted separately, because the tile itself may cost more than the labour. Tile on steep or hard-to-reach slopes is also quoted separately. We would rather say that here than surprise anyone.

The useful habit

After any storm, after any trade has been on the roof, and once a year regardless: have someone look at the tile from the roof, not the ground. Slipped tiles in particular are hard to see from below and easy to see from above.

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