Pressure Washing a Tile Roof – When It’s Worth It and When It’s Not

Tile roofs accumulate branches, leaves, and other debris as well as moss over time. A clean roof is pleasing to the eye, but a tidy appearance also indicates the roof’s condition. It’s good to keep a tile roof clean between coatings. But is pressure washing a tile roof justified? In short: it depends on what you’re planning to do with the roof after washing.

Can You Pressure Wash a Tile Roof?

A pressure washer’s effectiveness is based, as the name suggests, on pressure, which removes dirt efficiently. The washer’s impact is so effective that it also wears down the tile roof’s important coating. Pressure washing a tile roof exposes the tile’s porous surface.

Water gets trapped in the porous tile. Water expands when it freezes, so when the water alternately freezes and thaws as the weather changes, the tile can start to crack and eventually split. This is called frost damage. Water can penetrate through a cracked tile to the underlayment. If the underlayment has deficiencies, the water continues its journey into the building’s structure, where it can cause damage.

A porous tile is also a favorable surface for moss. Moss absorbs water like a sponge, creating ideal conditions for frost damage.

When Should You Not Pressure Wash a Tile Roof?

If you’re not planning to coat the tile roof after washing, it’s not advisable to pressure wash the roof. A pressure washer wears down the tile’s coating, exposing the tile’s porous surface. Therefore, a pressure washer is not part of routine annual maintenance equipment.

If coating is not planned soon after washing, it’s recommended to leave the pressure washer in the garage and clean the roof mechanically by brushing. After this, it’s worth applying a growth inhibitor to the roof to prevent moss growth. For this, you can use, for example, Tikkurila’s Kilpi roof cleaner.

If the roof already has abundant moss, coating the roof is likely due.

When Is It Worth Pressure Washing a Tile Roof?

Cleaning a tile roof makes sense when the roof is intended to be coated after washing. In this case, the exposure of the tile’s porous surface caused by the pressure washer doesn’t matter, as the coating restores the tile’s water-repellent smooth surface. Read more about tile roof coating in our article here.

How Is Pressure Washing a Tile Roof Done?

If there are damaged or even missing tiles on the roof, it’s good to replace them with intact ones before starting the pressure washer. This keeps the underlayment as dry as possible during washing. It’s also worth checking the tightness of roof penetrations and the condition of the underlayment before pressure washing.

When pressure washing, you must consider the washing direction. You must not wash upward at an angle so that excessive water reaches the underlayment.

If your tile roof needs care, we’ll gladly wash and, if necessary, coat your roof. Our estimate visit is always free. During the estimate visit, you’ll receive valuable information about your roof’s condition as well as a fixed quote for the work.