Condition ratings
A thick moss coat sits on the concrete tiles. Does that, by itself, force condition rating 3?
Not quite. A thick moss coat on the concrete tiles is growth sitting on the covering, and that sight alone does not force rating 3. Moss can hold moisture and hide a tile edge, which is worth a clear sentence. It is not, by itself, proof the tiles have failed. Ask what the surveyor could still see of the tile surface under the growth, and keep that note separate from any leak they actually found.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Moss is a living coat. On concrete tiles it can slow the way water leaves the slope and it can hide a cracked nib or a slipped edge, but the coat is not the tile. Rating 3 means the element is serious, urgent, or both, and it is the cue to get written quotations before you are legally committed. A green or brown carpet of growth does not, by itself, say the tiles have reached that point. If the surveyor could still see sound tiles between the clumps, the covering may sit at rating 2, where a repair or replacement is needed but is not serious or urgent, or even at rating 1 if they judge that only normal maintenance applies.
What the growth conceals is the real limit. A visual inspection does not scrape a whole slope, and it does not guarantee that the laps hidden under moss are sound. If the report cannot see the tile surface, the honest mark for that hidden part is NI, not a guessed rating 1. The what to do now note advises you. It does not send the seller a bill for a strip-and-recover because the tiles looked furry. Ask whether any tile was cracked, laminated or out of place once the moss is imagined away, and keep a leak, if one was found indoors, as its own sentence.
What should you ask your surveyor?
- Could you see the tile surface under the moss, or only the growth?
- Did you find cracked, laminated or displaced tiles, separate from the coat?
- Is any part of this slope NI because the moss hid it?
What are the typical next steps?
- Separate the moss note from any leak the report actually describes.
- Do not brief a roofer to replace the slope solely because of growth.
- Ask the surveyor which rating they applied to the tiles themselves.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If moss blocks a gutter as well, does the tile rating change?
Not automatically. A blocked gutter is rainwater goods. The tiles keep the rating given to the tiles.
Does scraping moss count as the repair the rating describes?
Only if the surveyor called the growth the defect. Clearing it may show a tile fault that still needs its own look.