Fit tongue-and-groove panelling to a lath and plaster wall — HomeGraft

Batten out a lath and plaster wall properly, then fix tongue-and-groove panelling securely without damaging the fragile plaster behind it.

TP-01Clear the room and check the wallMove furniture away from the wall and lay dust sheets on the floor, because old lath and plaster sheds fine dust and grit as you work. Press firmly on the wall in several places — if it feels soft, bouncy or crumbles, make a note of the spot. Sort out any damp, bulging or badly cracked plaster before you cover it, as panelling will hide a problem, not fix it.

2 each · Dust sheet

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TP-02Work out what's behind the lath and plasterLath and plaster walls are usually pre-1930s and are fixed either to timber studs or to timber battens over solid brick or block. Run a stud detector or magnet across the wall — a line of small, closely spaced points every 25-40mm is the lath fixings, not a stud. Tap the wall: a dull, solid knock in the middle of a bay usually means masonry behind, while a hollow, drum-like sound means a timber stud partition. A small 3mm pilot hole in an inconspicuous spot confirms it — pale timber dust means studs or battens, hard grey grit with a solid stop means brick or block.

1 each · Stud detector or strong magnet

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TP-03Take safety precautions before you drillCables and pipes can run almost anywhere behind lath and plaster, and old wiring isn't always in the usual safe zones. Use a detector, but still treat every drilling point as if something could be there — old lath nails can also throw off a cheap detector's reading near metal studs or conduit. Find your stopcock (usually under the kitchen sink) and check it turns freely before you start, so you can shut the water off fast if you hit a pipe. If you have any doubt at all, isolate the relevant circuit at the consumer unit before drilling.

TP-04Mark out and fix the batten frameworkFix horizontal battens (44x25mm) at floor height, ceiling height, and at 400-600mm centres between, running through the lath and plaster into whatever is behind it. Where a timber stud sits behind, pre-drill and drive a 5x60mm wood screw into the centre of the stud, spaced to the stud centres you found earlier. Where solid brick or block sits behind, drill a 6mm hole through the lath and plaster into the masonry, insert a 6mm wall plug to a depth of 45mm, then drive the screw home. Never rely on the lath and plaster itself to hold the weight — the timber or masonry behind must always take the fixing.

6 each · Timber batten, 44x25mm x 2.4m

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1 box · Wood screws, 5x60mm (box)

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1 pack · Wall plugs, 6mm (pack)

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TP-05Level and pack out the battensCheck every batten with a spirit level as you fix it, both along its length and against its neighbours. Lath and plaster walls are rarely flat, so pack behind the battens with plywood shims (3-6mm) at the screw points to pull the whole run into one plane. Step back and sight along the wall before moving on — any dip or bow will show through the finished panelling.

1 pack · Plywood shims (pack)

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TP-06Cut and fix the first panelPlan your first board so the run finishes with an even width at both ends of the wall, rather than a thin sliver in a corner. Cut the tongue-and-groove board to length, check it's plumb with a spirit level, and fix it through the face near the grooved edge into each batten. Drive fixings just below the surface so they're hidden by the next board or by filler later.

1 m² · Tongue-and-groove panelling

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1 box · Panel pins, 1.6x25mm (box)

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TP-07Fit the remaining panels across the wallPush the groove of each new board onto the tongue of the last, tapping gently with a wood block so you don't damage the edge. Secret-nail through the base of each tongue into every batten, angling the pin so it's hidden once the next board goes on. Check every third or fourth board with a spirit level to catch any drift before it becomes obvious.

4 m² · Tongue-and-groove panelling

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TP-08Cut boards around sockets and switches safelyIsolate the circuit at the consumer unit before you cut or drill anywhere near a socket or switch. Mark the cut-out on the board, check with a detector for any cable running to the accessory, then cut the opening with a jigsaw. If the extra thickness of the battens and panelling means the socket no longer sits flush, fit a socket spacer box rather than extending the cable yourself.

RULES

2 each · Socket spacer box

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KNOW THE RULES

Part P of the Building Regulations covers notifiable electrical work. Fitting a spacer box to an existing socket isn't notifiable, but adding new circuits, sockets or rewiring is — that work must meet Part P and normally needs a qualified electrician or building control sign-off.

TP-09Fit the final board and scribe it to the cornerMeasure the gap for the last board, allowing for the fact that corners in old lath and plaster walls are rarely square. Hold the board in place, mark the corner's profile onto it with a pencil and offcut, then cut along the line. Fix it the same way as the other boards, packing behind it with shims if the corner is uneven.

TP-10Fit trim to finish the edgesFit scotia or quadrant beading along the top and bottom of the panelling to cover the gap left by the battens. Where panelling now sits in front of the existing skirting, either remove and refit the skirting on top of the new surface or fit a wider skirting to match the extra depth. Fix trim into the battens you already fitted, never into the bare lath and plaster.

3 each · Scotia beading, 2.4m length

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TP-11Fill, sand and finish the panellingFill any visible pin holes with a matching wood filler and leave it to dry fully. Sand the filled areas smooth with fine sandpaper, then wipe away the dust with a dry cloth. Apply your chosen paint, varnish or oil following the tin's instructions, letting each coat dry fully before the next.

1 tub · Wood filler (tub)

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1 pack · Fine sandpaper (pack)

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1 tin · Paint, varnish or oil (tin)

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TP-12Clear up and dispose of wasteVacuum the floor and skirting thoroughly, as lath and plaster produces a lot of fine, gritty dust that settles everywhere. Bag offcuts and old plaster debris separately, since broken lath can have nails and splinters in it. Take rubble and offcuts to a household waste site if your bin collection won't take them, then wash and dry your tools before putting them away.

1 pack · Rubble sacks (pack)

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