How often should you clean your roof?

Most people never look at their own roof. Out of sight, out of mind. Then one day you are backing out of the driveway, you glance up, and there it is. Dark streaks, green patches, the lot.

So how often should you actually be cleaning it, and is pressure washing even the right way to do it? Let us clear that up.

How often is often enough

For most Melbourne homes, a roof clean every few years is plenty. You are not doing this monthly. As a rough guide, every two to three years if your roof gets a lot of shade, sits under trees, or you are near the bay where moisture hangs around. Every four to five years if it gets good sun and airflow and stays fairly clear.

The real answer is to just keep half an eye on it. If you start seeing green growth, black streaking or lifting lichen, that is your sign. Those are not just ugly. Moss and lichen hold moisture against your tiles and work their way into the gaps, and over time that shortens the life of the roof.

Why you should not blast it with high pressure

Here is where a lot of people get into trouble, including some so-called pros. Your instinct is to hit a dirty roof with as much pressure as possible. Makes sense. It is filthy, so blast it clean.

The problem is that roof tiles, especially older concrete and terracotta ones, have a protective coating. Smash them with a high pressure lance and you strip that coating right off. You can crack tiles, force water up under them, and flood your ceiling. We have seen it happen. You get the roof looking clean for a day, and quietly do a few thousand dollars of damage in the process.

What soft washing actually does

Soft washing is the proper way to clean a roof. Instead of relying on brute force, it uses a low pressure application and the right cleaning solution to kill the moss, mould and lichen at the root. The growth dies off and washes away, and the tiles are left clean without being battered.

The upside is twofold. Your roof comes up clean, and because soft washing kills the growth rather than just knocking it off the surface, it stays cleaner for longer. Blasting only removes what you can see. The spores are still there, and they come straight back.

The short version

Clean your roof every few years, sooner if it is shaded or you spot green and black growth. Do not let anyone high pressure your tiles unless they have a very good reason. Soft washing is safer, lasts longer and protects the roof you have already paid for.

We do roof soft washing across Keysborough and south-east Melbourne, and we are happy to get up there, take a look and tell you honestly whether it even needs doing yet.