Planning wants brick. The wall has 100mm of insulation on it. Those two facts are in direct conflict on a lot of UK projects, and brick slips are how the conflict gets resolved.

The concept is straightforward: achieve a brick appearance without building a brick wall. The execution is where the decisions are, because there are two quite different products both called brick slips, and they suit different situations.

Why not just build in brick

On an insulated facade, brickwork has to be supported. The insulation cannot carry it, so the load has to return to the structure through a support system of brackets, angles or a masonry support frame. That is a designed, engineered element with a cost and a lead time attached.

Then there is depth. Insulation plus a cavity plus a brick skin is a substantial build-up. On a tight site, at a boundary, or where the wall meets a pavement, the depth simply may not exist.

And on frame construction, whether timber, steel or modular, the weight of a brick skin is often the deciding factor before anything else is considered.

Brick slips remove all three problems. They add a brick face without adding a brick wall.

Mineral versus clay

This is the choice that matters, and it is not primarily about appearance.

Mineral brick slips are applied as part of the render system build-up. There are no individual units to fix and no separate pointing operation. The brick appearance, including the joint pattern, is formed as the finish is applied. The result is a fraction of the weight of clay and considerably faster to install.

Clay brick slips are thin sections cut from real fired brick. They are bonded to the base coat individually and pointed with mortar, exactly like conventional brickwork at a smaller scale. The material at the face is genuine clay, with the depth of colour and surface variation that only firing produces.

When to choose mineral

Weight is the governing constraint. Frame or modular construction. Large-scale housing programmes where the installation speed changes the programme meaningfully. Situations where the budget will not stretch to clay and the appearance requirement is a brick look rather than brick material.

When to choose clay

Conservation work. Planning conditions that specify clay, or that require a match to surrounding stock close enough that only real brick will pass. Prestige elevations where the facade will be examined at close range. Anywhere the specification says brick and means it.

What planning officers actually look at

If consent is conditional on matching adjacent brickwork, three things decide whether the finish is accepted, and only one of them is the brick itself.

Colour and blend. Real brickwork is never one colour. An elevation that reads as a single flat tone looks wrong even when the base colour is right. Slips should be mixed across several packs during installation so the variation distributes evenly rather than appearing in patches.

Mortar colour. Consistently underestimated. Pointing occupies a large proportion of the visible elevation, and the same slip with a light mortar versus a dark one produces two noticeably different walls. Agree it on a sample panel, not from a chart.

Corners and reveals. This is where a brick slip facade is most likely to be caught out. A flat elevation is easy. Returns, window reveals and terminations are where the eye goes, and where a poorly detailed job reveals that the brick is only a facing. Corner units maintain the bond around returns and are what make the difference.

The build-up

Either type sits as the outer layer of a tested brick slip system, and the layers below are not optional extras.

1. Substrate surveyed and prepared, with adhesion testing on a representative sample of each property type
2. Insulation adhesive-bonded and mechanically fixed per the project fixing schedule
3. Reinforced base coat with mesh fully embedded, giving impact resistance and crack control
4. Primer to regulate suction and provide the correct key
5. Brick slip finish, bonded and pointed for clay, applied as part of the system for mineral

The fixing pattern in step two differs depending on the finish, because clay carries more weight than mineral. This is exactly why the finish should be chosen alongside the system rather than picked afterwards. Selecting a clay finish on a build-up specified for render means revisiting the fixings.

Where they get used

Social housing retrofit under the Warm Homes Plan, where planning frequently requires the property to look substantially as it did. Conservation area work and extensions. High-rise residential refurbishment. Steel and timber frame new build. Modular schemes. Feature panels and plinth details on otherwise rendered elevations, where a band of brick breaks up a large expanse. And interior feature walls, where clay slips do a job no wallpaper manages.

Before you specify

Get physical samples and look at them in daylight against the brick you are matching. Screen colour is not reliable, and clay in particular varies between batches because it is a natural fired material. On anything larger than a single property, put up a sample panel on site and get it approved before the main works begin.

If you are working to a planning condition, that sample panel is also your evidence.

Order samples to check the finish in daylight, or speak to our technical team about the right build-up for your project.

Compare the two ranges: mineral brick slips and clay brick slips.