Gentle Roof Cleaning for Older Roofs

Signs your roof needs a careful approach

Tiles that have weathered to a soft, sandy surface, slates that ring dull when tapped, nails that have rusted through, ridge mortar that has cracked into chunks and moss that has grown into the gaps between tiles are all signs that a roof needs care.

Many roofs on Victorian and inter-war houses, and some post-war estates, fall into this group. So do outbuildings that have been ignored for years.

Checking before cleaning

We start by looking at the roof closely and noting any slipped or cracked tiles, missing slates, open joints or flashing that has lifted. Where photographs help, we share them so you can see what we see.

If the roof is fragile, the order of work changes. Small repairs may come first, or we may clean section by section so a loose tile can be reset as soon as it is found rather than after the moss has been disturbed around it.

Hand removal rather than force

On an older roof, the bulky moss is lifted off by hand in small sections. Scrapers are used along the tile surface rather than levered underneath, and we avoid walking on areas that will not take weight.

The aim is to take the moss off without taking the tile with it. On some roofs, very old moss has been holding loose tiles in place, and removing it reveals a repair that is needed anyway.

Treatment for what is left

After hand removal, a low-pressure soft wash and biocide, where suitable for the roof, deals with the remaining algae, lichen and spores. There is no high-pressure rinse. The treatment works over the following weeks, so the roof keeps improving after we have gone.

This is the same method we use on newer roofs, just applied with more attention to how much the surface can take.

When cleaning is not the right answer

Sometimes an older roof is at the point where tiles are failing faster than they can be reset. Cleaning will improve how it looks and help it shed water, but it will not reverse age. If we think a roof is close to the end of its life, we say so honestly and explain the options.

Our guide to roof cleaning versus replacement covers that decision in more detail.

Listed buildings and conservation areas

Owners of listed properties or homes in conservation areas should check with their local planning authority before work that could change the roof's appearance, such as repairs with non-matching materials. Cleaning itself is usually a maintenance task, but it is sensible to ask if you are unsure.

What older roofs are commonly covered with

Older houses in Hampshire, Surrey and Sussex carry a mix of handmade clay tiles, machine-made clay, natural slate and early concrete tiles. Each ages differently. Handmade clay varies in thickness and can delaminate in thin layers. Early concrete tiles may have lost most of their surface. Slate holds up well, but its nails corrode. Knowing which you have tells us how much weight and handling the roof can bear, and where to be most careful when lifting moss away from the edges.

Ask for a free quote

Tell us the age and type of roof if you know it, and send a photo if you can. We will advise whether a gentle clean is suitable and what, if anything, needs repairing first. Quotes are free across Hampshire, Surrey and Sussex.