Wall Skimming & Full Room Re-Skim by a Plasterer in Lewisham, SE13

This project took place in the ground-floor reception room of a Victorian terraced house in Lambeth, South London, close to the Lewisham borough boundary in the SE13 area. The room featured original cornicing, a period ceiling rose, and a substantial chimney breast that had been stripped back and rebuilt in concrete blockwork as part of a wider renovation. The property was mid-refurbishment, with flooring removed and first-fix electrics and pipework still exposed along the back wall, indicating a full structural and cosmetic overhaul was underway.

When our plasterer arrived on site in Lewisham, the reception room walls were in a heavily stripped-back state. Large sections of old plaster had been hacked off, leaving behind patches of bare sand-and-cement render, exposed brick, and raw substrate across the main walls and chimney breast flanks. The chimney breast itself had been completely rebuilt in dense concrete blockwork — entirely bare with no bonding coat or render applied. Loose and flaking remnants of old plaster were visible at mid-height on both side walls, and the surfaces showed uneven suction across the face of each wall. Rewiring channels were visible along the back wall near the consumer unit, and loose timber battens and plasterboard sheets were stacked around the perimeter of the room.

The scope of work covered the complete re-skim of all four walls in the main reception room, alongside the full plastering of the newly built concrete block chimney breast from scratch. The chimney breast required a two-coat sand-and-cement scratch coat system before any finish skim could be applied, given the dense and highly porous nature of the blockwork. The flanking walls to the chimney breast, which retained partial sections of the original sand-and-cement render, needed to be levelled with bonding coat where the old plaster had been hacked away, before the entire wall face could receive a continuous multi-finish skim coat. All four main room walls required the remaining loose plaster fragments to be removed, any deep voids filled with bonding compound, and the wall surface treated with a diluted PVA bonding agent to regulate suction before skimming. The area around the rewiring channels near the consumer unit was carefully filled and set hard prior to the main skim to prevent cracking along the electrical chase lines. Plasterboard sheets visible in the photos — stacked ready for use — suggest that certain sections of the ceiling or partition areas were scheduled to receive dry-lining as part of the broader renovation, though the main wall plastering was the primary scope for this visit. The chimney breast recess opening and its surrounding reveals were also to be plastered on all internal faces.

Prior to applying any plaster, all loose and flaking remnants of the original sand-and-cement render were hacked back to a firm substrate across every wall surface. The bare concrete blockwork of the chimney breast was thoroughly dampened down to reduce suction before the first scratch coat was applied. All walls were brushed free of dust and debris, then painted with a diluted PVA solution — mixed at approximately 1 part PVA to 5 parts water — and left to become tacky before bonding coat was applied to the deeper recesses and patched areas. Electrical chase lines along the back wall were filled using bonding plaster and allowed to set fully before plastering commenced, reducing the risk of shrinkage cracks appearing through the finish coat.

The chimney breast was tackled first, as it required the most build-up time. A scratch coat of sand-and-cement render was applied to the bare blockwork in two passes, with the first coat keyed with a comb scratcher and allowed to partially cure before the second levelling coat was floated off. Once the render had firmed sufficiently, the chimney breast breast face and flanks were brought forward to a consistent plane ready to receive multi-finish. Across the main room walls, bonding coat was applied to all areas where the old plaster had been removed, built up flush with the remaining original render, and left to set firm. Once the bonding was ready, the full wall surfaces were given a continuous scratch coat of Thistle Multi-Finish plaster, laid on from top to bottom and spread evenly across the entire wall face including the chimney breast. After approximately 20 to 25 minutes — once the first coat had taken on — the finishing coat was applied in long, overlapping strokes using a steel trowel, working from the ceiling line down to the skirting level. Each wall was trowelled up in stages as the plaster stiffened, with water misted on to assist the final burnishing pass. Internal angles at the chimney breast reveals were formed cleanly using an angle trowel, and all arris edges were checked with a straight edge before the plaster was left to cure. The finished surfaces show an even, flat, pale pink-to-grey tone consistent with a correctly set multi-finish skim.

The primary challenge on this project was dealing with two completely different substrates on the same wall plane. The chimney breast had been rebuilt entirely in concrete blockwork, which is highly porous and absorbs moisture rapidly, while the flanking walls retained patches of the original sand-and-cement render alongside areas of bare brick and exposed substrate. Achieving a flat, consistent surface across both materials — without differential shrinkage or suction variation causing the finish coat to crack or pull away — required careful staging of the work. The density of the blockwork also meant that the scratch coat needed a longer curing window before it was stable enough to skim over, adding time pressure to the schedule.

To manage the mixed substrates, the chimney breast was treated as an entirely separate plastering sequence from the surrounding walls. The blockwork was pre-wetted, then rendered in two separate sand-and-cement coats with sufficient drying time between each pass. Bonding coat was used across all hacked-back sections of the main walls to bring them level before the finish skim was applied. By allowing each layer to reach the correct firmness before proceeding, the multi-finish skim coat was applied to a uniform surface with consistent suction across the entire room. All angles and reveals on the chimney breast were formed using an angle trowel and checked straight with a feather edge rule, ensuring the overall wall plane was true from ceiling to floor.

By the end of the project, all four walls of the reception room had been re-skimmed to a smooth, flat surface ready for painting. The chimney breast — which arrived on site as bare concrete blockwork — was fully plastered on its face, flanks, and internal recess reveals, and sat flush with the surrounding wall plane. The finish coat across the room shows an even, consistent tone with no visible trowel drag lines, suction patches, or differential drying. The chimney breast recess opening was neatly lined on all reveals, and the cornice at ceiling level was preserved intact throughout. The room was left clean, with all plastering debris removed and the floor dust-sheeted where accessible.

The homeowner now has a fully re-plastered reception room with a consistent wall finish throughout — including a chimney breast that was bare blockwork at the start of the project. The room is ready for painting and final fix, with all wall surfaces stable, flat, and correctly cured. Having the plastering completed as a single continuous phase — rather than patching individual areas at different times — means the entire room will take paint evenly without visible joins or shadow lines between old and new plaster. The client could proceed directly to skirting board fitting and decoration once the plaster dried fully.

Plastering over concrete blockwork alongside patched sand-and-cement render requires a clear understanding of how different substrates absorb moisture and behave during curing. Applying a single-coat skim directly onto bare dense blockwork without a properly cured render base will almost always result in cracking or delamination as the plaster dries unevenly. An experienced plasterer working in Lewisham and South London understands how to sequence coats correctly — using the right bonding and scratch coat materials at the right build thickness — so that the final skim coat adheres uniformly and stays stable long-term. Cutting corners on preparation at this stage creates problems that become visible only after decoration, and are costly to rectify.