Before a plaster feature wall is troweled: TV backing, outlets, LED channels, the drywall level, primer and a sample board, in the order a Toronto crew works.
Home Renovations · October 30, 2026 · 8 min read
Before a plaster feature wall gets its first troweled coat, everything that will sit in or on that wall has to be in place: the wood backing for a TV mount, every outlet and cable box, the channel for any LED strip, the grilles and the trim. The drywall under it has to be flat and primed with something the plaster can grip. A troweled finish is built from thin, overlapping passes across the whole wall, so a hole cut later or a patch made later shows as exactly that.
The plaster itself is the last few days of the job. Most of what decides how the wall looks happens before anyone opens a bucket, and it takes the framer, the electrician, the drywall finisher and the plasterer working in the right order. Below is the wall layer by layer, what has to be settled before the finish, and how we use a sample board to check colour and sheen in the room's own light.
Six layers, and each one belongs to somebody. On a TV wall the first two do most of the work and nobody sees them once the room is done.
Solid wood blocking between the studs wherever a TV mount, a floating shelf or a heavy mirror will bolt on.
Outlet and switch boxes, a recessed box behind the TV, a pass-through for the HDMI cables, and the feed for any LED strip.
Joints taped and coated, screws covered, sanded flat. Skimmed over the whole sheet when the wall will be lit from the side.
A water-based primer with grit mixed in, left to dry right through, so the plaster grips and dries at an even rate.
Two or more thin troweled coats. The last one is pressed hard with a clean trowel when the finish calls for a sheen.
Wax or a sealer picked for the room. A hallway wall gets touched far more often than a bedroom wall.
The order is the point. Nothing in the first two layers can change after the fifth goes on without cutting into the finish.
This is a beige troweled panel framed in moulding. Look at what was placed before the plaster went on.
Every one of those was decided while the wall was still bare drywall. Moving any of them now means cutting the finished panel, and the repair would sit right in the middle of the frame where the eye goes first.
The TV, the power, the lights and the trim. On a TV wall, settle the screen size and the mounting height first, because the blocking, the recessed box and the outlets all follow from that one decision.
| In or on the wall | Settled | What happens if it is late |
|---|---|---|
| TV mount position and the blocking behind it | Before the drywall goes up | The mount goes into drywall alone, or the finished wall is opened to add wood behind it |
| Recessed box and cable path behind the TV | Before the drywall goes up | Cables hang below the screen, or a channel is cut through the plaster |
| Outlets, switches and the LED feed | At the electrician's rough-in | New boxes are cut into the finish, and the cut edges never match the trowel marks around them |
| Channels or aluminium profiles for LED strips | During drywall finishing | A strip stuck on afterwards shows its glue line and lights up every ridge |
| Grilles, thermostat, alarm keypad | During drywall finishing | The plaster is worked around a device already in place, or the device moves later and leaves a scar |
| Moulding frames and baseboard | Before the plaster, then masked | Trim added later meets the plaster at a joint that gets caulked over a finished surface |
| Colour and finish, on a sample board | Before the material is ordered | The colour is picked from a fan deck under store lights and reads differently in the room |
Our carpenters set the blocking and any shelving on the same wall, the way they do for our custom built-ins and shelving, so the backing is where the mount will actually land.
Not always. Level 4 means the joints and screws are taped, coated and sanded smooth. Level 5 adds a thin skim of compound over the whole sheet, so the paper face and the taped joints absorb the same way and look alike in hard light. A drywall contractor explains the difference in this JLC answer on Level 5 drywall versus veneer plaster.
Plaster makers do not agree on it. Earthaus, for one, says Level 4 drywall with a gritted latex primer is enough for its plasters, and that the primer must be fully dry before the first coat. Our call on site comes from the light the wall will get, not from the product label.
An LED strip along the edge of a feature wall, like the one on the TV wall at the top of this page, throws light almost flat across the surface. Light at that angle picks out every ridge, joint and screw dimple, and a plaster coat a millimetre or two thick follows whatever is under it. When a wall will be lit that way, we skim the whole surface before priming. A wall lit straight on by a ceiling fixture is far more forgiving. Where lights go and what they do to a finish is covered in our post on layering and placing renovation lighting.
Sound paint can take plaster. Peeling or chalky paint is scraped back first, a glossy coat is scuffed, and the gritted primer goes over all of it. Heavy texture, such as a knockdown pattern carried down from the ceiling, is skimmed flat before anything else, because a thin plaster coat shows the texture right through.
So the plates sit flat on finished plaster and cover a clean edge. In this basement room the electrician set two round boxes high on the wall, two square ones lower down and one near the floor. The plasterer worked up to each box and kept its edge taped. Covers and plates go on after the protective coat.
The green tape along the ceiling, the side walls and the baseboard does the same job around the outside. The plaster stops on the straight line the tape sets instead of feathering onto the next surface. The drywall under this wall was hung and finished by the same crew that does our drywall installation and repair, so the base was planned with the finish in mind.
On a sample board, in the room. For a plaster or special finish we make a sample board first and hold it against your wall in that room's light, as on every painting and plaster job we do. A troweled finish moves with the light. The same grey reads warmer under a yellow bulb and flatter on a cloudy afternoon, and the trowel marks that look soft at noon can look busy under a spotlight.
When the board is up, these are the things to look at:
Drilling. Any hole added after the finish needs a repair in a surface that cannot be blended in one spot, because the trowel pattern and the pressed sheen run across the whole wall. A small scuff often buffs out, or takes a touch of wax. A hole does not. That is why the mount, the boxes and the hooks come first.
If you want art or a mirror on a plaster wall later, a picture rail on the ceiling or a hanging system on the trim leaves the plaster alone. TV and fixture installs on walls that are already finished are part of our handyman services, and on our own feature walls they go onto the backing that was set for them.
Day to day, a soft dry or barely damp cloth is all the wall needs. Skip abrasive cleaners. A wall that gets bumped a lot, like a hallway or the side of a staircase, is better sealed than waxed, and that is settled at the sample board, together with the colour.
Yes, once the joints are taped and sanded and the wall is primed with a primer that has grit in it, left to dry fully. If the wall will be lit from the side by an LED strip, we skim the whole surface first so the joints do not show through.
Yes, when the wood backing and the cable box were put in before the plaster. The mount bolts through the finish into the backing, and the cables run inside the wall to a box behind the screen.
A light scuff often buffs out or takes a touch of wax. A hole or a gouge can be filled, but the patch rarely matches the trowel pattern around it, which is why openings are planned before the finish.
On the dry walls of a bathroom, over primed drywall, yes. Inside a shower it is a different build on cement board with a waterproof membrane, planned together with the rest of the bathroom waterproofing.
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