How to Fix Skirting Boards and Architrave with Woodscrews

Gather these before you begin. You may not need every item depending on whether you are working on masonry or stud walls.

For fixing skirting boards and architrave, a 4mm woodscrew is the standard choice across UK trade and DIY. It provides enough holding strength to pull the board firmly against the wall or door lining, without being wide enough to split the timber or MDF. Our premium woodscrews collection covers every diameter from 3mm to 8mm. For delicate or very thin architrave sections, a 3.5mm screw may be more appropriate to avoid splitting.

A good rule is that the screw length should be at least double the thickness of the board being fixed. Most standard skirting boards are 15mm to 20mm thick. This means a 50mm or 65mm screw is typically the right choice. The screw needs to pass through the board and penetrate the wall material or timber stud behind by a meaningful amount. For masonry walls with plaster, you need extra length to account for the plaster depth before reaching solid brick or block.

On masonry walls, you need to drill a hole through the skirting and into the brick or block behind it, insert a wall plug into the masonry hole, then drive the woodscrew through the skirting and into the plug. The plug expands as the screw enters it, gripping the masonry firmly. Space your fixings at no more than 600mm apart, and always countersink the screw head so it sits below the surface. Drill a pilot hole through the skirting board first to prevent the timber splitting. Countersink that hole too so the screw head has somewhere to sit flush.

For plasterboard stud walls, use a stud detector to find the timber uprights behind the board. Mark their positions clearly along the bottom of the wall before you position the skirting. Studs are typically spaced at 400mm or 600mm centres. Drive your 4mm woodscrews directly into the stud timber through the skirting board. This gives a very solid fixing and does not need a wall plug. Pre-drill and countersink the skirting first, just as you would for masonry. On sections of wall between studs, you can use a bead of grab adhesive to add hold, with the screws at the studs providing the mechanical fixing.

Measure each wall individually from corner to corner. Mark the length clearly on the back of the skirting board. Cut to length using a mitre saw or mitre box and panel saw. For external corners, cut both boards at 45 degrees so they meet cleanly around the corner. For internal corners, cut the first board square and butt it into the corner. Then scribe the second board to fit the profile of the first. Scribing a board means cutting a coped joint that follows the shape of the first board's moulding. This produces a joint that stays tight even if the timber moves slightly over time.

Hold the skirting board against the wall in its final position. Mark where each fixing will go on the face of the board. On a stud wall, the fixings need to line up with the studs behind the plasterboard, so transfer your stud positions across to the board first. On masonry, you can place fixings at even intervals of up to 600mm, with additional fixings close to each end and each corner joint. Place your fixings in the thick, flat section of the skirting, typically around 10 to 15mm below any moulded profile at the top. Keep fixings away from the very bottom edge where the board is thinnest.

Drill a pilot hole at each fixing position using a wood drill bit. For a 4mm woodscrew, a pilot hole of around 2.5mm to 3mm through the skirting board is appropriate. This prevents the board splitting as the screw is driven. After drilling each pilot hole, use a countersink bit to open out the top of the hole so the screw head can sit below the surface of the timber. The head needs to be fully recessed so you can fill over it cleanly later. For masonry walls, mark the wall position through each pilot hole by holding the board in place and marking with a pencil or tap through the hole with a small nail. Then remove the board and drill the masonry holes with a suitable masonry bit.

For masonry walls, tap a wall plug into each of the holes you have drilled in the wall. The plug should sit flush with or just below the wall surface. It must not protrude beyond the plaster, or the skirting will not sit flat. If you are applying grab adhesive as well (recommended for uneven walls), apply it now in a zigzag bead across the back of the board before fixing it in place. Press the board firmly against the wall, bottom edge to the floor, and check it is level and sitting correctly before driving any screws.

Drive each woodscrew through the skirting board and into the wall plug or stud behind. Drive them firmly until each head sits just below the surface of the board. Do not overdrive. If you crack or dent the surface around the hole, the countersink was not deep enough and you need to drill it out a little more. Work from the centre of each board outwards so you can pull any bow out of the board as you go. Check the board is sitting flat and not pulling away from the wall at any point. If the wall is uneven and the board cannot be pulled tight by the screws alone, combining with grab adhesive on the back is the right approach.

Using a tape measure and pencil, mark a consistent gap of 5mm to 6mm back from the inner edge of the door lining on all four sides of the door frame. This creates the decorative step between the lining and the architrave face. Use a combination square or a piece of timber cut to the right width to run this line evenly. These pencil marks show you exactly where the inside edge of your architrave will sit and where to measure each piece to length.

Cut the horizontal head piece to the length between the two points where the pencil lines cross at the top of the door frame. Cut a 45-degree mitre at each end of the head piece, angled outwards. Then cut the two vertical leg pieces. Fix the left leg first. Hold it in position against the lining with its inside edge on the pencil line, then mark where the mitre at the top needs to be. Cut the leg at 45 degrees at that point. Repeat for the right leg. Dry-fit all three pieces before fixing anything. Check the mitre joints close up neatly and that the pieces sit flat against both the lining and the wall plaster.

Mark your fixing positions on each piece of architrave. On the leg pieces, place fixings at roughly 200mm to 250mm intervals. On the head piece, two or three fixings are usually sufficient. Position each fixing in the flat, thicker section of the moulding rather than in the decorative profile itself. On the inner edge (the side closest to the door opening), fixings go into the door lining. On the outer edge (closest to the wall plaster), fixings go into the wall or stud behind. Drill a pilot hole at each mark and countersink it so the screw head will sit cleanly below the surface. Use a 3mm pilot hole for a 4mm screw in architrave timber or MDF.

Apply a small amount of wood adhesive to the mitre joint surfaces before bringing the pieces together. Fix the left leg in position first using your countersunk woodscrews, checking it is upright with a spirit level as you go. Then bring the head piece in and fix it with its mitre pressed tightly against the leg's mitre. Finally, fix the right leg in the same way. Drive each screw until the head sits just below the surface. The combined effect of glued mitres and screwed fixings gives a joint that stays closed and a fixing that holds firmly even on an imperfect door lining.

Combining grab adhesive with woodscrews gives a stronger, more stable result in most situations. The adhesive fills minor gaps between the back of the board and an uneven wall surface, distributing the load across the full length of the board rather than concentrating stress at each screw point. This reduces the risk of the board pulling away from the wall between fixings over time as the timber moves seasonally. The screws hold the board firmly in position while the adhesive cures and provide mechanical security if the adhesive bond is ever disturbed.

Screwing without adhesive is the right approach when the skirting may need to be removed later, for example to run pipes or cables behind it, or in a rented property where you want to be able to restore the room cleanly. Screws into wall plugs on masonry, or directly into studs on stud walls, give a fully removable fixing. Driving the screws home neatly with good countersinking and filler still produces a clean painted finish. The only drawback compared to the glue-and-screw method is that the board may not pull quite as flat against an uneven wall between fixing points.

Once all boards are fixed, press wood filler into each countersunk screw hole using a small flexible knife or your finger. Press it firmly so there are no voids around the filler. Overfill each hole slightly, so the filler sits a fraction proud of the surface. Leave it to dry fully according to the filler manufacturer's instructions. Once dry, sand each filled area back flat with 120-grit sandpaper until it is perfectly flush with the surrounding timber or MDF. Run your finger across it. You should not be able to feel where the screw is. If you can, add a second thin coat of filler and sand again.

Run a thin bead of decorator's caulk along the top edge of the skirting where it meets the wall plaster. Cut the nozzle of the caulk tube at a 45-degree angle for a neat bead. Smooth the bead with a damp finger in one continuous stroke. Decorator's caulk is flexible and will accommodate the small movement that happens as the timber responds to changes in temperature and humidity. Standard filler at this joint will crack over time because it is rigid. On external corner mitre joints on skirting, use wood filler rather than caulk, as caulk is not strong enough to hold a corner joint tightly over time.

If you are working with bare MDF or unprimed timber, apply a primer coat before your top coats. MDF absorbs paint into its surface and edges if applied without a primer, resulting in a rough, uneven finish. Pre-primed MDF skirting can go straight to a first undercoat. Apply two top coats of your chosen paint, typically a satin or eggshell finish for skirting and architrave, allowing each coat to dry fully before the next. The filled and sanded screw holes should disappear completely under a good quality paint system applied in thin, even coats.

Driving a woodscrew directly into timber or MDF without a pilot hole forces the fibres apart. In softwood, this often causes a small split that may not be visible until it is painted. In MDF, it can cause the surface layers to separate around the screw, creating a visible raised ring. Always pre-drill a pilot hole to around 70% of the screw shank diameter through the board before driving the screw. It takes a few extra seconds per screw and makes a significant difference to the finish quality.

A screw that is too short will not penetrate the wall or stud far enough to grip properly. The fixing will feel solid at first but will work loose over time. On the other hand, a screw that is excessively long on a stud wall can punch through the far side of the stud and potentially hit something behind. Choose the correct length for your wall type using the guide in the screw size section above. If you are unsure, err towards a length that gives you at least 25mm penetration into the solid material beyond the board and any plaster.

If the screw head sits flush with the surface rather than just below it, you cannot fill over it neatly. A slight bump will always show through paint, especially in raking light. Always use a countersink bit after drilling the pilot hole, and drive the screw until the head sits 1mm to 2mm below the timber surface. This gives the filler enough depth to sit properly and be sanded truly flat.

If you are fitting skirting and architrave after the walls have been fully painted, every drill hole, screw drive, and fill operation risks marking the painted wall surface. The correct sequence is to fix the skirting and architrave after plastering and any first fix electrical or plumbing work, but before the final decoration of the room. This gives you clean surfaces to work against, and any minor marks or scuffs from fixing can be addressed as part of the final paint phase.