Heritage Flint Wall

An extension to an existing flint and brick garden wall, built to match what was already there and to carry on across ground that rises 750mm along its length.

The footings, and why they are bigger than they need to be

The footings are C25 concrete, 600mm deep by 600mm wide — around ten cubic metres, placed by volumetric mixer. That is more than the wall strictly requires, and it is deliberate.

The reasoning is simple arithmetic. Rebuilding a flint wall is expensive — the flintwork is slow, skilled and hard to match. Concrete is not. Spending a little more on the footing to eliminate any risk of ground movement is far cheaper than any chance of having to take the wall down and do it again. On this kind of work the invisible decisions are the ones that determine whether it is still standing in fifty years.

Because the ground rises, the footing is stepped rather than sloped — three steps along the run, shuttered so no concrete or below-ground brickwork is wasted. Each step raises the wall by three courses.

Setting out to match what was already there

The wall begins as a curve at the same height as the existing, straightens, and only then takes its first step. The step is positioned where the spacing works out evenly, so the new panels line through symmetrically with the existing flint. Getting that setting-out right at the start is what makes an extension read as part of the original wall rather than an addition to it.

The construction

Double skin for the first five courses, with two-brick-width pillars at roughly 1.6 metre centres to match the existing wall. Between each pillar sits a flint display panel, 1.6m by 1.6m, backed by a single skin of brickwork. Mesh ties were built into the single-skin sections so the flintwork ties properly back into the structure behind it.

Steel plate headers were formed and fixed to support the brick-on-edge, which allowed the panels and the wall to be completed in full before any decision had been taken on the flintwork. That sequence matters: it means the structure was finished and stable on its own terms, and the flint could then be knapped and laid into it as a considered decision rather than something the programme had already committed to. Seventeen panels in total were knapped and laid.

The two walls running back towards the arch start at 1.8 metres and curve down to meet the existing detailing where they join it.

Brick was Ibstock red, supplied by the client along with the flint, sand and cement — an arrangement that suits a client who wants to buy the materials directly, with our fee covering the labour and setting-out.