Moss on a concrete tile roof in the British Properties

The situation

A large home in the British Properties has a concrete tile roof that's been darkening for years, with moss filling the gaps between tiles on the shaded side and debris collecting in the valleys from the tall firs around the lot.

The owner's main worry: cracked tiles. A previous contractor had walked the roof carelessly and left two broken tiles behind.

Why tile is different

Concrete tiles are durable against weather but can crack under a misplaced foot. They also have deep profiles where moss and needles pack in, which makes hand removal slower than on a flat shingle roof.

High pressure can erode the surface finish of older tiles and push water up between them, so pressure is kept low.

How we approach it

We plan where to step before we go up: on the lower third of each tile, where it's supported by the tile beneath, and on walk boards where needed. Fall protection is set before any cleaning starts.

Moss is lifted out of the tile channels and gaps by hand, then the surface is rinsed at low pressure. Valleys and the areas behind skylights and chimneys get extra attention because that's where water slows down and debris builds up.

We note any tiles that are already cracked or slipped, with photos, before we start and again at the end. Tile replacement is a roofer's job, but you'll know exactly what we found.

With this much tree cover, the gutters fill up as the roof is cleaned, so they're cleared at the same visit.

What to expect

A cleaner, lighter roof with moss removed from the joints, valleys clear, gutters running and a photo record of the roof's condition. Concrete tile gets its own approach to slowing regrowth, which we'll recommend for your roof.

Questions we hear