How to Fit Tongue and Groove — Step-by-Step UK Guide

What You'll Need

Before You Start

• Allow the tongue and groove boards to acclimatise in the room for at least 48 hours before fitting. Stack them flat with spacers between layers for air circulation.
• Check the wall for damp — do not clad over a damp wall without addressing the cause first.
• Use our Tongue and Groove Calculator for board quantities and our Timber Cladding Calculator for batten requirements.
• Locate pipes and cables in the wall before fixing battens — use a pipe and cable detector.

Step-by-Step Instructions

Step 1: Fix the Battens

Fix battens at 400-600mm centres, running perpendicular to the board direction. Use wall plugs and screws into masonry, or screws into studs on timber-frame walls. Check each batten is level and plumb. Pack behind battens where the wall is uneven to create a flat plane. Fix a batten at the top and bottom edges of the area being clad.

Step 2: Start with the First Board

Place the first board in the corner with the groove side facing the corner. Check it is perfectly plumb (for vertical installation) or level (for horizontal). Leave a 10mm gap between the board and the adjacent wall. Face-nail the first board through its face into the battens — the nails will be hidden by a corner moulding.

Step 3: Secret Nail Subsequent Boards

Drive a panel pin or brad nail at a 45-degree angle through the tongue of each board into the batten behind. This is called secret nailing — the next board's groove slides over the tongue and hides the nail. Use a nail punch to set the pin below the surface if needed. Do not hammer directly on the tongue — use a scrap piece of T&G as a tapping block.

Step 4: Fit Each Board Tightly

Slide each new board onto the previous one, tongue into groove. Tap gently along the length using a mallet and a scrap offcut as a tapping block. The joint should be tight with no visible gap. Do not force boards — if one does not fit, check for debris in the groove or a damaged tongue.

Step 5: Cut Around Obstacles

For light switches, sockets and pipes, mark the cutout on the board, drill a starter hole and cut with a jigsaw or coping saw. Leave 5mm clearance around socket faceplates. For pipes, drill a hole slightly larger than the pipe, then cut a slit to slide the board over.

Step 6: Fit the Last Board

The last board usually needs trimming to width. Measure the gap (accounting for the 10mm expansion gap), rip the board to width and face-nail it in place. The nails will be hidden by the corner moulding.

Step 7: Fit Trim and Mouldings

Pin scotia moulding or corner trim around all edges to cover the expansion gaps. Use internal corner moulding (quadrant or scotia) and external corner moulding (corner bead or planed corner piece) as needed. Mitre all corners at 45 degrees.

Step 8: Finish

Sand lightly with 120-grit paper if needed. Apply your chosen finish — oil, wax, varnish or paint. For a natural look, use clear oil or wax. For bathrooms, use marine-grade varnish or moisture-resistant paint. Apply two coats with light sanding between coats.

Common Mistakes to Avoid

• No expansion gap: Without gaps at edges, the boards buckle and warp when humidity changes. Always leave 10mm at all edges.
• Battens not level: Uneven battens create a wavy surface that is visible once boards are fitted — especially obvious on painted finishes.
• Not acclimatising the timber: Boards fitted straight from a cold, damp delivery van will shrink in a heated room, opening up gaps.
• Face-nailing all boards: Secret nailing keeps the surface clean. Only face-nail the first and last boards where trim will cover them.
• Forcing boards: Hammering too hard damages the tongue or groove, making the next board impossible to fit properly.

Cost Estimate (2026 UK Prices)

Use our Tongue and Groove Calculator and Timber Cladding Calculator for exact material lists.