The short answer
Cleaning is often worth considering, though no rule demands it. A buyer's surveyor reports on what they can see from the ground, and heavy moss or dark streaking invites questions about the covering underneath. Have the roof looked at first. A clean should follow a sound survey, because washing can show up damage and a coating can hide it from the next owner.
A tidy roof helps a sale only when the roof beneath it is sound. Here is what buyers and their surveyors notice, and where cleaning can mislead.
What a buyer's surveyor sees from the ground
A surveyor acting for a buyer usually begins on the pavement with binoculars, then looks into the loft if the hatch is accessible. They note what they can see: missing or slipped tiles, sagging lines along the slope, cracked flashing, blocked gutters and heavy growth. Moss and lichen show clearly from the road, so they often earn a line in the report.
Does moss on the roof put buyers off?
It can raise questions, and the questions matter more than the moss. A buyer reading "moss growth noted" may press for a lower offer, or ask for a roofer's opinion before exchange of contracts. A clean slope with a sound covering underneath gives the surveyor less to flag and gives the buyer less to bargain with.
A surveyor is judging condition, not colour. If the tiles beneath the moss are cracked or the ridge, the line of capping along the very top, is loose, a wash changes nothing in the report. It may even lengthen it, because once the growth is gone the faults are easier to spot from below. Our main page on roof cleaning and moss removal covers the methods in full.
Look at the roof first, then decide on a clean
Order matters here. Cleaning a roof that nobody has inspected is how sellers end up paying for a wash and then a repair, in that sequence, with the repair squeezed in just before completion.
Should you repair before you clean?
Usually you look first. We survey the roof, take photos of your own slopes, valleys and ridge, and show you which parts are sound and which are tired. If a few tiles are cracked or a hip, the sloping ridge at a corner, is loose, mending them before the clean means the roof is washed once and left finished. Our page on roof cleaning and repairs together explains how the two jobs fit.
If the covering has little life left, a clean will not hide that and should not be asked to. A buyer's surveyor will report a roof near replacement whatever its colour, and you are better placed knowing that before the house is advertised. Having a repair or re-roof priced early also lets you decide whether to fix it, or to leave it and expect a conversation with the buyer.
Coatings and strong washing: a caution before you sell
Some sellers hear that a coating will freshen the roof for viewings. The coating goes on over the tiles once they are clean, rather like masonry paint, and it brings cautions of its own.
Can a roof coating hide problems from a buyer?
It can sit over cracks, worn edges and tired mortar, which means a surveyor may ask what lies beneath and whether the surface was clean and sound when the coating went on. A layer applied over damp growth or loose material can peel, and a patchy finish draws more attention than moss ever did. You also hand the next owner a surface to maintain. Our page on roof coatings sets out the questions to put to anyone offering one.
Harsh washing is the other trap. Marley does not recommend jet washing, since a blast of water can wear the surface of a covering and cut into the years it has left. A roughened, worn surface is something a buyer's surveyor may note, so a gentler method such as soft-wash roof cleaning suits a roof you are about to sell.
What to tell the buyer, and what to keep
Selling is paperwork as much as presentation. If you clean the roof, keep the written price, the date of the work and any photos from the job. When a buyer's solicitor asks what has been done to the property, a short, dated record answers the question.
Does the buyer need to know a biocide was used?
It is sensible to say so. A biocide is a treatment that kills moss and algae, and professional products come with conditions of use that the person applying them must follow. Passing on the product name from the job means the next owner knows what is on the roof and when it went on.
Timing helps too. A roof treated a good while before the listing photos are taken will usually look better than one cleaned the day before, because a treatment does its work gradually and the dead growth then loosens and washes off. If a sale is coming up, give us the date you are aiming for, and the visit can be planned around it. Ask for a survey of your own roof, with pictures of what is found and one written price for whatever it needs.
More on cleaning before a sale
Will a clean roof raise the asking price?
Nobody can promise a figure for a sale price. What a clean roof does is remove an easy point for a buyer to haggle over and make the covering simpler for a surveyor to judge. The real value is a sound roof under the clean, so repair anything the survey finds first.
Can I clean the roof myself before listing the house?
Roof work from a ladder carries a real risk of falling, and the HSE is clear that biocides meant for professionals are off limits to the public. A ground-level tidy of gutters and overhanging branches is a safer start. For the roof itself, a surveyed and properly set up job protects you and the tiles.
The full picture: Roof cleaning and moss removal in Taunton ยท More short answers