On a tile roof, the walking is the risk - not the water

What is tile roof cleaning?

Tile roofs clean differently from asphalt because the failure mode is different. There are no mineral granules to wash away, so the argument about pressure is less absolute - but tile cracks and slips under foot traffic, and a broken tile in the middle of a slope is worse than the moss that was on it. The other thing to know: the tile is a rain shield, and the underlayment beneath it is the actual waterproof layer. Cleaning does nothing for that layer, and it is usually what ages out first.

Signs you need tile roof cleaning

• Dark biological growth in the valleys and along the lower courses where water lingers longest
• Moss establishing in the channels of barrel or S-profile tile, where debris collects and stays wet
• Concrete tile that has gone patchy and blotchy rather than evenly faded - often a sealer breaking down, not dirt
• Leaves and needles packed under the tile lip or behind the chimney, holding water against the underlayment
• Visible cracked or slipped tiles, which need replacing before anything is washed over them
• Lichen crusting on the exposed weathered face of older clay tile

Seeing something not on this list? Browse roof cleaning problems by symptom →

How tile roof cleaning actually works

1. 1

   Identify the tile: clay, concrete, or a coated concrete

   Clay is fired and colour-through. Concrete tile is often surface-coloured and sometimes sealed. A coated concrete tile can be stripped of its finish by an aggressive clean, which changes the appearance permanently even though the tile is undamaged.

   Watch forA quote that never asks what the tile is. Clay, concrete and coated concrete tolerate different treatment, and the answer changes the plan.

2. 2

   Planning the access route before anyone steps on the roof

   A competent tile crew works out where the load-bearing points are, uses the courses that carry weight, and often works from ladders, walk boards or roof hooks to minimise how many tiles get stood on at all.

   Watch forA crew that walks straight up the middle of the field. Every additional footfall is a chance of a hairline crack that will not show until it leaks.

3. 3

   Replacing damaged tile first

   Broken and slipped tile is found and dealt with before washing. Water directed at a cracked tile goes straight to the underlayment.

   Watch forA cleaner who reports zero broken tiles on an older roof. It is unusual to find none, and it usually means nobody looked.

4. 4

   Application at a pressure appropriate to the tile

   Concrete tile tolerates more than asphalt does, but "more" is not "a lot". The point of the solution is still to do the cleaning; water at any real force finds its way sideways under tile laps and onto the underlayment.

   Watch forPressure aimed upslope, or into the tile laps. Driving water under the tiles is the way a cleaning job produces a leak two weeks later.

5. 5

   Clearing valleys, laps and the debris underneath

   On tile the debris that matters is often not on top but caught in the valleys and beneath the tile edges. That is what holds moisture against the underlayment, and it is the part that actually shortens roof life.

6. 6

   Deciding about sealing, honestly

   Concrete tile is porous and can be sealed after cleaning, which affects appearance and water absorption. It is a genuine option, and it is also the most upsold item on this job.

   Watch forSealing presented as required maintenance. It is a choice, not an obligation, and on clay tile it is generally not the right one.

What does tile roof cleaning cost?

Tile roof cleaning is usually quoted per square foot or as a job price and typically runs above asphalt work, because access is slower, tile replacement may be needed and the crew has to control foot traffic. Sealing, where offered, is priced separately. The Cost Guide has current ranges.

See the full tile roof cleaning cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →