How each method works
Air-pole cleaning uses compressed air delivered through a long telescopic pole. The air gets under the moss and lifts it away from the tile. The operator works from the ground or a ladder.
Pressure washing a roof uses a jet of water at high pressure, often with a rotary surface cleaner or lance. It usually involves someone working on or close to the roof, and it uses a lot of water.
Tile safety
Walking on a roof is one of the main causes of cracked tiles, especially on older concrete tiles and slate. Because the air pole is used from ground level or a ladder, nobody needs to stand on the roof. High-pressure water can also wear the surface of older concrete tiles and force water up under the laps where tiles overlap. That is the main reason we prefer air for roofs.
Water and mess
Pressure washing a roof produces a lot of runoff carrying moss, grit and slurry down the walls, onto windows and across the ground. Air cleaning is drier, so the moss mainly falls as clumps that can be gathered up. Either way there is some debris to clear, and we tidy gutters and ground afterwards.
Where pressure washing still has a place
Pressure washing is still a very useful tool. It is often the right choice for driveways, patios and paths, and occasionally for a particular roof area such as heavily stained ridge tiles or a flat surface. We would rather tell you honestly when we plan to use water or pressure than hide it. If any part of your job needs it, it will be on your written quote.
- ✓Air pole: main method for tiled and slate roofs
- ✓Softwash: algae and staining on render, fascias and some roof surfaces
- ✓Pressure wash: hard ground surfaces, and specific areas where needed
Results that last
Neither method stops moss growing back on its own. Spores and fragments remain in the surface of the tile. A biocide treatment after cleaning is what helps slow regrowth, whichever method was used for removal. When comparing quotes, check whether treatment is included.
Questions to ask any roof cleaner
Ask how they will remove the moss, whether anyone will walk on the roof, whether any water or pressure will be used and on which parts, whether a treatment is included and how they will leave the gutters and ground. A good contractor will answer clearly and put it in writing.
Frequently asked questions
Is air cleaning completely waterless?
Air is used to remove the moss. A biocide treatment, if included, is applied as a liquid, and some jobs need softwashing or pressure washing in specific areas, which we explain on the quote.
Does pressure washing damage roof tiles?
It can wear older concrete tiles and push water under the overlaps, which is why we prefer air for roofs.
Which is quicker?
It depends on the roof, but air cleaning avoids the long clean-up of water runoff from walls and windows.
Will the moss come back after either method?
Moss regrows over time after any cleaning method. A biocide treatment helps slow it down.