The short answer
Yes. Moss hides slipped tiles, cracked ridge bedding and failing pointing, and cleaning exposes them. Small fixes such as refixing a tile or re-pointing a short run can usually be done on the same visit once you agree them. Larger faults, such as a sagging ridge or a run of perished tiles, are photographed, explained and quoted separately, so you decide before anything extra is done.
What moss hides and cleaning reveals
A thick moss cover looks like a green blanket, but underneath it is a different story. Moss grows into the gaps between tiles and into cracked mortar, where it holds water and slowly pries things apart. Tiles that have slipped a few millimetres, chips and cracks, and joints that have lost their pointing are all invisible from the ground until the growth is gone.
That is why a clean doubles as an inspection. Once the surface is clear, the roofer can see dark tide marks beneath a tile, hairline cracks, tiles that rock under a gentle press, and lead around chimneys and wall junctions that has lifted or split.
Photographs matter here. A homeowner cannot see their own roof, so we photograph the faults we find and show you, on the pictures, what they are. You can then judge for yourself whether the fix is worth doing now. Our roof cleaning and moss removal page describes the visit from start to finish.
Slipped and cracked tiles
Slipped tiles are common on roofs that have been held in place by their own moss. Nail fixings corrode or the tile is simply old, the tile slides down a little, and the gap beneath exposes the underlay or batten. A slipped tile can usually be pushed back and refixed with a clip or a new nail. A cracked tile needs replacing, and a matching one is not always simple to find on older roofs.
Underlay is the thin layer beneath the tiles, and it is the back-up that keeps most of the water out when a tile fails. If it has perished or torn, the repair is bigger than a tile swap.
Where only a few tiles are involved, replacing them on the day is practical and cheap in terms of access, since the ladders or tower are already up. If a whole area is tired, patching tile by tile only moves the problem along, and that calls for a proper discussion of a larger repair. For reference, MyBuilder's roof repair guide, updated in August 2026, puts minor repairs at £100 to £300 and moderate repairs at £500 to £1,000 across the UK. Your own roof gets its own total, put in writing after a look at it.
Ridge tiles, hips and pointing
Working from the top down, the ridge is the horizontal crest of the roof, while a hip is a sloping crest that runs to the eaves from an outward corner. Both wear special capping tiles, traditionally bedded on mortar. Mortar cracks and crumbles with age, and moss makes that worse.
Under BS 5534:2014 a bed of mortar is no longer relied on alone to keep capping tiles on, so a modern ridge or hip also has a mechanical fixing. A ridge that rocks, or shows daylight at the joint, may need re-bedding, and an older ridge may need fixings added. MyBuilder's slate guide, updated in August 2026, gives £300 to £600 for re-bedding or replacing ridge tiles and £200 to £400 for repointing ridge or hip tiles, as typical national ranges.
A short run of cracked pointing can be repaired on the day. A long ridge that has lost its bedding along its length is a bigger job, and a rebuild may suit it better. Either way you see the photographs first and the written quote follows. A loose ridge in a gale can drop tiles onto a path, so it is not a fault to leave.
Gutters, valleys and the details around them
While the roofer is at the eaves, the first row of tiles and the gutter get a look too. Sagging brackets, cracked unions and silt-filled runs are the usual finds, and they connect straight to the moss itself. We cover that side in our page on moss in gutters.
A valley is the internal crease between two slopes, and rain from both pours down it. Leaves pack in and the lining beneath is tested at every shower. Around the chimney, flashings (metal strips, often lead, dressed between the stack and the tiles) are checked for gaps and curled edges. Soakers, the small pieces of metal that interleave with tiles at joins, are harder to see but can be spotted when they bulge or stain.
None of this is looked at in depth from a ladder. It is a visual survey with a camera, and anything that needs a closer view is flagged for a proper repair visit. If a fault is absent, you will be told so, and what lies beneath a covering we have not lifted stays an open question until it is lifted.
How extra work is agreed
Nothing extra gets done without your say-so. Small items you have already approved, such as refixing a handful of tiles, can be done at the same visit. Anything larger is photographed and explained, and the quote follows in writing. You are free to take it, to wait, or to have someone else do it.
Sometimes the better advice is to delay the clean. Where tiles are broken in several places, washing over them would drive water through the gaps, so the repair goes first and the clean follows. The page on soft wash biocide cleaning explains why gentle methods suit tired coverings.
A roof that is already leaking jumps the queue, because stopping the water comes before anything cosmetic. Ring 01793 626096, or use WhatsApp or the form with a picture. Both the repairs and the cleaning sit under our written 10-year guarantee on workmanship, and rubbish leaves with the crew.
If you would like to see how a visit runs from the first call, the roof cleaning and moss removal hub lays it out, and the page on moss on a shed roof covers the smaller buildings in the garden, which deserve a check as well.