Roof Cleaning and Moss Removal

Pressure washing gives a dramatic before-and-after, but it strips the surface coating from concrete tiles and leaves them porous, so moss returns faster. On slate it can crack or lift individual slates and drive water up under the laps into the roof space. It can also loosen ridge bedding on older roofs and fill the gutters with grit.

Manual removal is slower but gentler. Moss is scraped and brushed off working down the slope, so nothing is pushed under the courses above. The roof keeps its surface, and any loose or slipped tiles can be dealt with as they are found rather than discovered after the next storm.

A typical domestic clean has three parts. First, moss and lichen are removed by hand from the slopes, ridge and hips. Second, the gutters, valleys and outlets are cleared, because the debris that comes off the roof has to go somewhere and left in place it simply blocks the drainage. Third, a biocide is applied to kill remaining spores; it works quietly over the following weeks rather than producing an instant change.

Expect the roof to keep shedding small amounts of dried growth for a few weeks afterwards. That is normal and is the treatment doing its job.

Most house roofs are a one-day job once access is in place. Steep pitches, tall elevations, conservatories or extensions beneath the slope and heavy growth can extend that, and safe access has to be arranged before any work starts.

A typical domestic roof clean with manual moss removal, gutter clearance and biocide treatment runs from around £300 to £800. Where your roof falls depends on its size and pitch, how heavy the growth is and how the roof can be reached safely. The written quote lists what is included, so you can compare like with like.

Be cautious of quotes that pair a clean with a sealant or coating. Coatings on ageing concrete tiles are expensive, can trap moisture and do not restore a tile that has already deteriorated, so we do not recommend them.

Moss on a sound roof is mostly cosmetic. It is worth removing when it is thick, filling the gutters, lifting slate edges or holding damp against porous tiles. If the roof is near the end of its life, or the tiles are already flaking, cleaning will not fix that and the money is better put toward repair or replacement. We will tell you honestly which situation you are in.

Cutting back overhanging branches and keeping gutters clear does a lot to slow regrowth between cleans, and a clean fits naturally into a regular roof maintenance routine.

Ask how the moss will be removed, whether the gutters and valleys are cleared afterwards, what treatment is applied and how access will be arranged. A good roof cleaning service will also tell you about any slipped tiles, cracked ridges or worn flashings it finds, with photos, whether or not that leads to more work.