The eleven that matter
None of these alone means your roof is finished. Three or four together usually does.
- Tiles losing their surface. Concrete tiles shed their coloured facing as they age, going pale, rough and porous. Once they soak up water they get heavier and start to break up in frost.
- Granules in the gutters. The gritty sediment washing out of your downpipes is your roof, gradually leaving.
- Slipped tiles that keep coming back. One slipped tile is a repair. Tiles slipping every winter across the whole roof usually means the nails have rusted through — "nail sickness" — and no amount of putting them back will fix it.
- Daylight through the roof from inside the loft. Take a torch up on a bright day, turn it off, and look. Pinholes of light mean gaps.
- Torn or crumbling felt. Look up at the eaves from outside, or at the underside of the tiles from the loft. Original 1960s bitumen felt goes brittle and tears into strips. When it's gone, the tiles are your only defence.
- Sagging along the ridge or between rafters. A roof line that dips is a structural signal, not a cosmetic one. Get it looked at soon.
- Damp patches or staining on upstairs ceilings, particularly after wind-driven rain rather than steady downpours.
- Cracked or missing ridge mortar along the top of the roof, with visible gaps where the mortar has fallen out.
- Green and heavy moss growth holding water against the tiles and lifting their edges.
- Your roof is 50+ years old and has never been touched. Concrete tile and its original felt simply do not go much further than that.
- Rising heating bills with no other explanation — a wet or poorly ventilated roof space loses a surprising amount of heat.
The four that panic people unnecessarily
We get called out for these constantly, and most of the time the answer is a few hundred pounds, not a few thousand.
- A single slipped or cracked tile. Genuinely a one-visit repair on an otherwise healthy roof. Don't let anyone use it as a doorway to a re-roof conversation.
- Moss. Moss is a symptom, not a disease. On a sound roof it is a cleaning job. It only matters when it is sitting on tiles that are already porous.
- Streaky black staining. Usually algae. It looks awful and does essentially nothing to a sound tile.
- One damp patch after a storm. Wind-driven rain finds temporary ways in around flashings and chimneys. Trace the source before assuming the whole roof has failed — it's very often a flashing problem measured in hundreds, not thousands.
A ten-minute check you can do yourself
You do not need to go on the roof. Please don't.
From the ground, walk the full perimeter with binoculars if you have them. Look along the ridge for gaps and daylight. Look at the verges — the sloping edges at the gable ends — for missing mortar. Look for tiles out of line, and for any that are a different colour, which usually means a previous patch. Check the gutters for plant growth and sagging.
From inside the loft, on a dry, bright day, with the light off: look for daylight, look for staining on the timbers, feel whether any rafters are damp, and look at the state of the felt above the insulation. Photograph anything that worries you.
Then get a second opinion. Our roof health check turns your answers into a plain-English verdict in about two minutes, and it will happily tell you your roof is fine.
When it's genuinely urgent
Call somebody today, not next month, if you have water actively coming into the house, if you can see a sag or dip in the roof structure, if tiles have come off in a storm and left the felt exposed, or if a chimney is visibly leaning. Everything else can wait for a proper inspection and a considered decision.
If it is the middle of the night and water is coming through, we do emergency call-outs across Crawley and the surrounding towns.
Last reviewed August 2026 by the Bonwycks Roofing team. Prices are genuine local ranges for Crawley and the surrounding towns and are reviewed twice a year — your own quote will always be specific to your roof.