Clay vs Concrete vs Slate Roofs: Cleaning Differences

Concrete tiles

Concrete tiles are the most common on post-war homes. They are heavy and durable but have a surface coating that wears over time. Once that coating has gone, the tile becomes porous and moss takes hold quickly.

Concrete tiles are the most vulnerable to damage from pressure washing because the surface strips so easily. Hand moss removal and low-pressure treatment protect what coating remains. Our concrete tile roof cleaning page has more.

Clay tiles

Clay tiles are common on older houses and many period properties. They weather to attractive tones but can become soft and flaky with age, and older handmade tiles vary in thickness.

Clay tiles can crack if walked on carelessly, so access and weight distribution matter. Gentle hand removal and treatment suit them well.

Natural slate

Slate is smooth and dense, so moss grows more slowly on it than on rough concrete. But slates are thin and brittle, and they are held by nails that can corrode over time. A slate that has lost its nail can slide.

Walking on slate needs care, and pressure washing can lift slates or push water under them. Our slate roof cleaning page explains our approach.

Where moss grows on each

On concrete, moss forms thick cushions across the whole tile surface. On clay, it gathers in joints and on the textured face. On slate, it tends to grow along the edges and overlaps.

The common principles

Whatever the material, the same rules apply: check the roof first, remove bulky moss by hand, treat at low pressure where suitable, never pressure-wash the tiles and clear the gutters at the end.

Mixed roofs

Some houses have mixed materials, for example a slate main roof and a concrete tile extension. Each section is treated according to its material.

Telling the materials apart

Concrete tiles are usually thick, regular in shape and often have a rough, sandy texture or interlocking profile. Clay tiles are thinner and often curved, with warm red, orange or brown tones, and they may vary slightly in shape. Slate is thin, flat, smooth and dark grey or blue-grey, often fixed in neat rows with no texture.

Ageing and cleaning results

Concrete tiles that have faded will look clean but not new after cleaning. Clay tiles often reveal attractive tones once moss is gone. Slate tends to look much as it did originally once surface growth has been treated. Being realistic about results helps owners decide what to expect.

Repairs on each material

Replacing a concrete tile is usually straightforward if a matching profile is available. Clay tiles can be harder to match, especially handmade ones. Slate repairs use matching slates and special fixings. Because we offer roof repairs, damaged tiles found while cleaning can be dealt with once you agree.

Other roof coverings

Some homes have less common roofs, such as stone slates, clay pantiles, fibre-cement slates or metal sheeting. Each has its own needs. Fibre-cement slates on older properties may contain asbestos and should be tested before any work that could disturb them. Ask us with a photo if you are unsure.

Gutter debris by material

Worn concrete tiles shed sand-like grit into gutters. Clay tiles shed less grit but can lose fragments as they age. Slate sheds very little. What you find in your gutters can hint at the roof's condition.

Walking on each roof

Concrete tiles are the most forgiving to walk on, though care is still needed. Clay and slate can crack under point loads. Access methods that spread weight are used on fragile roofs.

Gutters for every roof

Whatever the material, gutters are cleared at the end of the job.

Ask for a quote

Not sure what your roof is? Send a photo and we will tell you. Quotes are free across Hampshire, Surrey and Sussex.