Lime Plastering & Lime Render
for Heritage Buildings

Traditional plastering in lime

Traditional lime plastering is built up in coats, each allowed to cure before the next:

• Scratch coat — keyed to give the next coat something to grip.
• Float coat — straightened and consolidated to bring the wall true.
• Setting (finish) coat — a fine lime finish, trowelled smooth or left with a softer texture.

On ceilings and timber partitions we install lath and lime — riven or sawn timber lath fixed to the joists or studs, with haired lime backing coats pushed through the gaps to form a mechanical key. Where original lath survives and is sound, we keep it and repair around it.

We also carry out modern gypsum traditional plastering for extensions, new partitions and modern areas of the same building, and can run both systems side by side on one programme.

Lime render and external lime render

External lime render protects solid walls from rain while letting them dry out. For period elevations it is usually the correct replacement for failed or inappropriate cement render, which can crack, trap water and accelerate decay of soft brick and stone.

We apply external lime render to:

• Listed and period elevations, including full re-rendering after removal of cement render
• Stucco-fronted townhouses and mansard storeys
• Garden walls, outbuildings and boundary walls
• Repairs and patching matched to existing render

At Lancaster Gate we delivered the complete external render package from the fifth-floor mansard to ground, across six levels of a live heritage site, with a consistent finish across elevations completed months apart. See also our external rendering page.

Lime render specification

Getting the lime render specification right is the difference between a render that lasts for decades and one that fails in a few winters. We agree the specification with the architect or conservation officer and the client, covering:

• Binder: non-hydraulic lime putty, or natural hydraulic lime (NHL 2, 3.5 or 5) chosen for the exposure and the background. As a rule, the render should be weaker and more permeable than the masonry behind it.
• Aggregate: well-graded sharp sand, matched where needed to the colour and texture of existing work.
• Mix ratio and coats: typically two or three coats, with each coat no stronger than the one beneath.
• Hair or fibre: for backing coats where extra tensile strength is needed.
• Preparation: removing cement render and unsound material, raking joints, and dampening the background to control suction.
• Curing: protection from sun, wind, rain and frost, with misting so the lime carbonates properly. Lime work is seasonal; we plan external lime around the weather and avoid frost risk.
• Finish: float, sponge, roughcast or a limewash or breathable mineral paint.

If you have an existing specification from your architect or heritage consultant, we will price and work to it. If you do not, we can propose one for approval.

Case study: Lancaster Gate

Brought in 18 months into a three-year restoration, we mobilised up to 16 specialist plasterers and took on effectively the whole plastering scope: 4,000m² of traditional lime plaster applied back from bare brickwork, riven timber lath and lime where the original was beyond repair, the full external render, grassello di calce polished plaster, structural waterproofing to 13 basement vaults and the ornamental fibrous restoration. Read the Lancaster Gate case study.