One tile off is not usually a crisis, but the reason it came off often is. Here is how to judge the risk from the ground.
What the tile is actually doing
On a modern roof the tiles are the first line of defence and the breathable membrane underneath is the second. Lose one tile on a roof with sound membrane and you have lost redundancy rather than watertightness, at least for a while.
On an older roof with bitumen felt, or with no underlay at all, which is common on pre war Oxfordshire properties, a missing tile can let water straight in. That is the case where urgency jumps.
Judging it from the ground
Look for whether the gap shows dark timber and felt, whether neighbouring tiles have also shifted, and whether the loss is near a ridge, valley or verge where wind uplift is highest. A single tile mid slope is far less serious than a run of tiles at the verge.
Also look at your loft. If light comes through, water will too. If the felt below the gap is visibly torn or sagging, treat it as urgent.
Why tiles slip in the first place
Nail fatigue is the usual cause on older roofs. The nails corrode, the tile relies on its nib alone and eventually gravity wins. When one goes, others on the same batten are often close behind, which is why we always check the surrounding area rather than just replacing the one that fell.
Other causes are failed mortar at the verge or ridge, foot traffic from other trades, and storm uplift. Moss build up plays a part too by holding moisture against the fixings.
Immediate: multiple tiles gone, visible daylight into the loft, active dripping, or damage at a valley or chimney. Ring someone the same day and expect a temporary cover if weather is coming.
Within a week or two: one or two tiles off mid slope with sound membrane below. Within the month: a single cracked but in place tile, or minor verge mortar loss with no water ingress.
Can one missing tile cause a leak?
On an older roof with perished felt or no underlay, easily. On a modern roof with intact breathable membrane, often not immediately, but the exposed batten and membrane will degrade in sunlight over months.
How much does it cost to refit a slipped tile?
Typically 180 to 350 pounds as a minimum visit, which usually covers several tiles and a check of the surrounding area while access is in place.
Should I put a tarpaulin over it myself?
Only if you can do it safely from a secured position, which for most houses means not at all. A badly fixed tarpaulin can lift and pull more tiles off.
Will my insurer cover storm blown tiles?
Often yes if the storm was severe enough to meet the policy definition and the roof was in reasonable condition beforehand. Photograph the damage and keep the date.
Is it worth replacing all the nails at the same time?
If several tiles have slipped from the same area, re fixing the wider section is far better value than repeated single visits.
Evans Roofing & Maintenance Ltd, Witney, Oxfordshire. Call 07960 482233 for a free written quote.