Painting After a Kitchen Extension in London: New Plaster, Matching Decor and Open-Plan Continuity
How to approach painting after a kitchen extension in a London home — handling new plaster areas, matching existing decoration and achieving colour continuity in open-plan spaces.
The Post-Extension Painting Challenge
Having a kitchen extension built is one of the most transformative things you can do to a London terraced house. It opens up the rear of the property, brings in light, and typically creates the open-plan kitchen-dining-living space that is now the most sought-after configuration in urban residential design.
But once the builders have gone, the mess has been cleared and the new kitchen is in, there is almost always a significant decorating challenge waiting. The new extension space needs painting from scratch. The existing rooms behind it — typically the original kitchen area and the room beyond — need to be brought into visual harmony with the new space. And there is frequently a mix of new plaster, old plaster, exposed brick and plasterboard in the same field of view.
Getting this right requires planning as well as craft.
Understanding What You Have: A Surface Inventory
Before any painting starts in a post-extension property, it is worth doing a careful assessment of every surface in the affected area. In a typical London terraced house following a rear kitchen extension, you might encounter:
New plaster on extension walls. Likely skim over blockwork or plasterboard, probably four to twelve weeks old depending on when the builders finished. This needs a proper mist coat before any finish emulsion — see below.
Existing painted walls in the original kitchen. Previously painted surfaces that may have been disturbed during works — damp patches from a temporarily open roof, marks from scaffolding or dust, scuffs and dents from the building process.
Original Victorian plaster in adjacent rooms. If the living room or dining room has been opened up into the new space, there may be old lime plaster on party walls that was not touched in the works but needs to be brought into the new scheme.
Exposed brickwork. Many extensions deliberately leave one wall of the original house in exposed brick as a design feature. If you are taking this approach, decide in advance whether the brick will be sealed, limewashed, painted, or left entirely bare.
New plasterboard on ceiling. Extension ceilings are typically new plasterboard, which absorbs differently from the existing ceiling in the original house.
Mist Coat on New Plaster: Non-Negotiable
Any newly plastered surface — walls or ceiling — in the extension must receive a mist coat before finish coats are applied. This is a diluted emulsion (typically 70 per cent paint, 30 per cent clean water) that soaks into the absorbent new plaster, stabilises it and provides an even base.
Skipping this step is the single most common cause of post-extension painting problems. Without a mist coat, your finish coats will absorb unevenly, the colour will look patchy however many times you apply it, and the paint will not adhere well to the surface long-term.
Allow new plaster a minimum of four weeks to dry before mist-coating. In a typical London extension completed in autumn or winter, this may mean waiting until the heating has been running in the space for several weeks and the plaster has fully cured.
Matching Existing Decoration
One of the trickier aspects of post-extension repainting is matching the decoration in the parts of the property that were not significantly affected by the works. If your existing living room is painted in a specific Farrow & Ball colour from five years ago, and you want to carry it through into the new open-plan space, you have several options:
Repaint the entire affected area in fresh paint. This is the most reliable approach for consistency, even if it feels wasteful. Paint colours fade slightly with age, and a new pot of the same colour will often read slightly different on a five-year-old wall versus a newly painted one.
Match by reference. Take a painted-out chip from an existing wall to your paint supplier and ask for a match. Most trade suppliers and some retail outlets offer a colour-matching service that can get very close.
Use the opportunity to update. Post-extension repaints are a natural opportunity to reconsider your colour scheme for the whole ground floor. If you were going to repaint eventually anyway, do it all now.
Open-Plan Colour Continuity
The open-plan kitchen-dining-living configuration that rear extensions create can feel visually discordant if the colour scheme has not been thought through as a whole. The eye now travels across a much larger space, and inconsistencies — different heights for wall colour, changes in sheen level, a slightly different white on one ceiling versus another — are immediately visible.
Key principles for open-plan continuity:
Use the same ceiling colour throughout. Whether that is a flat white or a tinted ceiling colour, consistency across the ceiling plane unifies the space more than anything else.
Consider a single wall colour for the main walls, with variety in accents. A strong accent wall in the kitchen area and a quieter tone in the seating zone can work, but ensure the relationship between the two colours has been tested and agreed before painting starts.
Match your sheen levels. Eggshell on walls in the extension and matte emulsion on walls in the original room will read as two different surfaces even if the colour is identical. Decide on your sheen level and stick to it throughout.
Think about the transition point. Where the original house wall meets the extension, there is often a change in plane — a reveal, a structural column, or simply a junction between old and new. This transition is an opportunity for a deliberate colour break rather than a point at which an awkward mismatch becomes visible.
Woodwork and Kitchen Units
In a post-extension repaint, the woodwork — skirting, architraves, door frames — typically runs through from old to new spaces. It makes sense to repaint all woodwork in the affected area at the same time, using the same product and colour, to give a consistent finish.
Kitchen units, if newly installed, will typically be factory-sprayed and should not need painting. But if you are retaining or updating existing kitchen units as part of the works, this is often a good point to have them professionally painted in the same operation.
Getting the Timing Right
Post-extension painting is time-sensitive in one direction (wait long enough for plaster to cure) and flexible in another (the rest of the house can be done at any point). The typical sequence:
- Extension plaster is laid
- Wait minimum four weeks, ideally six
- Mist coat new plaster
- Allow mist coat to dry (four to eight hours)
- Fill and prepare all surfaces — new and old
- Two finish coats on walls and ceilings
- Woodwork in two to three coats
Plan the kitchen installation to follow the plastering by the required curing period, and schedule the decorator to arrive after the kitchen units are in but before any final fittings are installed. This gives the best access without the risk of paint on brand-new cabinet fronts.