Roof soft washing and pressure washing both clean a roof, but they work very differently, and choosing the wrong one can damage it. A roof covered in black streaks, mould or lichen makes a whole house look tired. Whether it should be soft washed or pressure washed depends on what your roof is made of and the condition it is in.

What is roof soft washing?

Soft washing applies a cleaning solution at low pressure. Illawarra Maintenance Group uses a sodium hypochlorite-based wash to kill mould and organic staining, followed where needed by a biocide that keeps working on moss and lichen after we leave. The solution does the work, not the force of the water.

Roof soft washing suits coated metal roofs such as COLORBOND, older tiles and anything fragile.

What is controlled roof pressure washing?

Pressure washing uses the force of the water to lift dirt and growth. On sound concrete tiles with heavy build-up, controlled pressure washing, with the pressure matched to the surface, gives a deep clean.

Soft washing vs pressure washing at a glance

• Metal roofs (COLORBOND and similar): soft wash.
• Older or fragile tiles: soft wash.
• Sound concrete tiles with heavy build-up: controlled pressure wash.
• Not sure: the roof is checked first and the method chosen to suit it.

Why high pressure can damage a roof

Used incorrectly, high-pressure cleaning can:

• crack or dislodge tiles
• strip protective coatings from metal and tiles
• force water under flashings and into the roof space
• wash mortar out of ridge caps on older tiled roofs

That is why the first step on every roof is checking its material and condition, then choosing a soft wash or a controlled pressure wash to suit it.

Protecting your property during a roof wash

• Downpipes that feed a rainwater tank are disconnected or diverted before washing.
• Nearby plants are wet down and rinsed.
• Gutters, solar panels and landscaping are protected.
• Keep pets inside while the work is done.

What to expect after a roof wash

Mould and staining clear on the day. Lichen dies quickly but takes several weeks to a few months to break down and wash away with rain, so the roof keeps improving after the clean. A clean roof usually lasts several years. Roofs under trees or in damp, shaded spots, such as many homes under the escarpment, regrow faster, and a light re-treatment every two to three years keeps them looking good. Read more in Why Moss, Mould and Lichen Grow on Illawarra Roofs.

Minor roof jobs while we are up there

If the clean shows up a cracked tile or some loose pointing, IMG can take care of minor work like swapping cracked tiles and repointing, and will photograph and report anything bigger.

Frequently asked questions

Is soft washing safe for COLORBOND roofs?

Yes. Soft washing uses low pressure, which is why it suits coated metal roofs.

Will my roof look clean straight away?

Mould and staining clear on the day. Lichen takes several weeks to a few months to break down and wash away with rain.

What about my rainwater tank?

Downpipes that feed a tank are disconnected or diverted before washing.

Book a roof wash

IMG washes roofs across Wollongong, Corrimal to Thirroul, Shellharbour and Kiama and Gerringong. See our roof washing page.

Call 0411 389 184 or request a free quote and we will be in touch.