How to Install Skirting Boards: 45° Corner Cuts and Flawless Fixing

Installing skirting boards (or baseboards) is the final step that gives a room its finished look: they protect the bottom of the walls and hide the junction between the floor and the wall. If the 45° corner cut often intimidates beginners, it is mastered in a few minutes with a well-adjusted miter saw. In this guide, we explain how to choose your skirting boards, calculate the quantity, make perfect corners and fix them cleanly, whatever the nature of your wall.

Choosing the right skirting board model

The skirting board must harmonise with your floor and your style. Solid wood models (oak, beech) offer a warm look but remain expensive. MDF (medium-density fibreboard) skirting boards are the best value for money: stable, factory-primed, easy to cut. PVC skirting boards are used mainly in renovation with prefabricated plastic corner pieces. In height, the standards range from 70 mm to 150 mm: the higher the ceiling, the taller the skirting board can be for a successful visual balance.

Calculating the quantity and preparing the room

1. Measure the perimeter of the room excluding the doors (the skirting is cut flush with the door frame, it does not go behind).
2. Add a 10 % margin for failed cuts and corners, especially if your walls are irregular.
3. Divide the total by the length of one skirting board (usually 2.40 m) and round up to the next whole number.
4. Let the wooden skirting boards acclimatise for 48 hours in the room, laid flat, to stop them from deforming.
5. Remove the old skirting boards and the traces of adhesive, then dust the bottom of the wall and the floor.

Cutting the 45° corners and straight joints

For an external corner, both skirting boards are each cut at 45°, face against the saw, so that the visible part meets in a point. For internal corners, use the method above: one straight board and one 45° cut. The joints on a long wall are made with a 45° bevel as well, or simply a square cut if you then glue a joint cap. A miter saw or a jigsaw with a 45° guide is enough; always check the angle on an offcut before cutting the final piece.

• Use a miter box or an electric miter saw set precisely to 45°.
• For an external corner, the right-hand skirting board is cut on a left bevel and vice versa.
• Always test the joint on an offcut: a 1° gap is immediately visible.
• Lightly sand the cut with grit 120 paper to remove splinters before installation.
• Locate the screws and power sockets: a pre-drilled skirting board installs faster than you would think.

Fixing the skirting boards: nails, adhesive or screws

On a plaster or brick wall, PU (polyurethane) wood adhesive in a cartridge gives a perfect hold: apply a wavy bead to the back of the skirting board, press it against the wall and hold it with clamps or temporary nails. On a very smooth concrete wall, better to combine adhesive and nails in the brick joints. Screw fixing with concealed screws (with wall plugs) remains the strongest for tall skirting boards, but forces you to fill the holes afterwards. Whatever the choice, start at the most visible corner of the room and finish at the door.

Finishing the joints and the seams

Once all the skirting boards are in place, fill the small imperfections: the joints between two skirting boards and the passage of the 45° cut are filled with flexible filler (acrylic) using a caulking gun. Smooth with a wet finger for a perfect finish. The joints between the skirting and the floor and wall are also treated with acrylic if you want a perfectly sealed look, or simply by leaving a small clean gap. Finally, apply a final coat of paint over the filled nail heads to even out the whole thing.

The mistakes to avoid

• Cutting internal corners with two 45°s on walls that are not square: the joint gapes.
• Installing the skirting board before the adhesive of the first row is dry: it slips and peels off.
• Forgetting the passage of cables and drilling into an electrical conduit: locate the sockets first.
• Forcing a wooden skirting board that is warping instead of letting it acclimatise.
• Applying the adhesive over the whole length: a wavy bead is enough, savings and hold guaranteed.

Installing skirting boards is a rewarding job that transforms a room in a weekend. By choosing a suitable model, calculating the quantity carefully and above all mastering the 45° corner cuts tested on offcuts, you get a result worthy of a professional. Take the time to finish the seams and joints with acrylic: it is what makes all the difference between a DIYer's installation and a clean installation that will last for years.