Three-coat plaster
Three-coat plaster and skim coats, when a wall has to be done over
Where a wall has failed beyond repair, it is plastered again as it was first built: a scratch coat, a brown coat and a thin finish coat, each left to dry before the next.
Three coats take longer than any other plaster work, and it is the only way to get a wall that behaves like the others around it. We use lime or gypsum, depending on what the house has. A skim coat over sound plaster is a lighter fix, and we use it only where the wall beneath is firmly bonded.
We don't skim over loose plaster, and we don't hang drywall. If a wall is better replaced with board, we say so.
What is included
Scratch, brown and finish coats over wood lath or masonry
Lime or gypsum plaster, chosen to match the house
A skim coat over sound plaster to even a patched wall
Straight corners and clean returns at windows and doors
Protection and a HEPA cleanup
What changes the job
What shapes the scope
Cost follows scope, so the written survey names each of these before you see a figure.
The surface underneath
Wood lath, brick and board each need a different first coat. We find out which you have before we price the work.
Lime or gypsum
Lime cures slowly and takes more days. Gypsum is quicker. The house decides which is right.
Season and humidity
Plaster dries best in steady, moderate conditions. Winter work needs heat and summer work needs ventilation.
The finish you want
A smooth trowel finish takes more passes than a sand or float finish. We make a sample board first.
How it goes
Four steps, in order
- 01
Step 1: Prepare and bond
Loose plaster is removed, the surface is cleaned and, where needed, a bonding coat goes on.
- 02
Step 2: Scratch coat
The first coat is pushed into the lath or masonry and scored, so the next one can grip.
- 03
Step 3: Brown coat
The second coat brings the wall flat and true, and is left to dry.
- 04
Step 4: Finish coat and cure
A thin finish coat is trowelled smooth. The wall then dries before it takes primer.
Rules
Permits and rules
Re-plastering an interior wall does not normally need a building permit. If framing, wiring or plumbing change at the same time, or the wall is part of a fire-rated assembly in a multi-family building, other rules may apply. We ask at the start.
Examples
Sample scopes
Written the way a survey writes them. Your own scope will name your own rooms.
- Sample
Dining-room wall
A 12-by-9 wall re-plastered in three coats over lath after a long-standing leak.
- Sample
Stair wall
A skim coat over sound plaster to level three earlier patches.
- Sample
Kitchen ceiling
A bay re-plastered over new lath, blended to the original ceiling's finish.
Sample content.
Before you call
Questions about three-coat plaster
Lime or gypsum plaster?
Lime fits the oldest houses and is softer and slower. Gypsum was common in many later houses. We look at what is on the wall and match it.
How long before I can paint?
Gypsum can be primed once it is fully dry, which takes days. Lime takes longer. We tell you what the mix needs before painting.
Can you plaster over drywall?
Yes, with a bonding coat, and only if the drywall is sound. It is rarely the better choice, and we will say so if so.
Can you work in winter?
Yes, with the house heated to a steady temperature. Cold slows the drying and can ruin a coat, so we plan around it.
Book a wall survey
Tell us what the wall is doing. We will come and read it, then write down what we found.