Installing an LED skirting board

The installation is decided before the delivery arrives. This is the part everyone takes for paperwork, and it settles everything that follows. A miscounted length costs you a few days of waiting. A forgotten power supply costs you an opened wall. Take an hour, a tape measure and a sheet of paper.

Measuring the run

Walk round the room, wall by wall, and write down each length as you go. Count only what will actually be fitted: subtract the doorways, the built-in furniture, the cupboard that runs down to the floor, the sliding glass door. Then add it all up.

1. 1.Measure the linear metres of wall to be lit, following the walls.
2. 2.Add 5 % for cutting offcuts.
3. 3.Divide by 2.5 — our profiles are supplied in 2500 mm lengths — and round up.

On a heavily broken-up run, that 5 % margin is not enough. If your sections are shorter than a metre and a half, each length yields only one usable piece and the rest goes in the skip. In that case allow generously, or send us your sketch.

Counting the corners, one by one

This is the step almost everyone rushes. An internal corner is a corner of the room seen from the inside: the four corners of a rectangular bedroom, for example. An external corner is a return in the wall — a pillar, a door reveal, the edge of a recess, the corner of a built-in masonry cupboard. They get forgotten because nobody ever looks at them.

Sketch the plan of the room freehand, with no concern for scale. Mark each corner with a letter: I for internal, E for external. Then count. As many internal corners as there are I's, as many external corners as there are E's. Add a connector everywhere two lengths meet on the same straight line. A pair of end caps closes an open run; a run that goes right round the room needs none. Finally, one light slot cover per length.

Deciding where the power supply goes

The LED strip runs on extra-low voltage. A transformer handles the step down from the 230 V of the home, and it needs somewhere to sit: ventilated, accessible, close to a supply point. A cupboard, a base unit, an access hatch in a suspended ceiling. Never shut inside a partition with no way in.

Now mark on your sketch the route of the extra-low voltage cable, from the transformer to the start of each run. If the wall is already finished, there are two routes: start from an existing socket and run the cable through the cavity of the skirting board itself, or drill discreetly behind a piece of furniture. If neither of them works in your home, it is better to find that out now.

This is the point we see missed most often: nobody has planned where the power comes in. A missing length can be ordered. A wall closed up over nothing has to be opened again.

Nothing exotic, and nothing you need to hire by the week. Here is what really earns its place.

• A tape measure, a pencil and a square for marking out the cuts.
• A mitre saw with a fine-toothed blade suited to aluminium. This is the one tool not to compromise on: it decides whether your corners are invisible or whether they are all anyone sees.
• A clamp. A 2500 mm length that slips during the cut gives a false angle, and nobody notices until the dry run.
• A fine file or abrasive paper to deburr every cut.
• A spirit level. A laser level if the floor is not true, which in a renovation is the rule rather than the exception.
• A cartridge gun if you are gluing. A drill, wall plugs suited to the substrate and a screwdriver if you are screwing.
• A cloth and a degreaser to prepare the wall where the adhesive will go.
• Scissors or a knife to cut the LED strip, only on its cut marks.
• Gloves. Freshly sawn aluminium cuts, and the edge of a mitre cut is decidedly sharp.

If you do not have a mitre saw, borrow one rather than attempting the job with a mitre box and a hand saw. Over twelve metres of skirting board, half a degree of error repeated four times shows in every corner of the room.

The finished wall

The most common case, and the simplest one to install. The wall is painted, the floor is down, you are adding the skirting board. Run your hand along the foot of the wall over the whole run: you are looking for ridges of plasterboard tape, adhesive residue, paint that is blistering. An aluminium profile will not bend to follow a bellied wall; it either comes away in the middle or leaves a gap.

Dust it down, then degrease the band where the adhesive will grip. On recent satin paint, a light sanding gives a far better key. If the wall is powdery — old plaster, paint that chalks under your finger — the adhesive will grip the dust, not the wall. Screw it instead.

The wall under renovation

The comfortable case, and the one to prefer when you have the choice. Everything is prepared before the finishes go on: bring the supply to where the transformer will sit, leave a tail at the start of each run, and record on a photograph where the cables go before the plaster hides them. You will be grateful for it in ten years.

After that the order is fixed: plaster, paint, floor, and only then the skirting board. A plastered and painted wall gives the even bearing surface that upward light output needs. Fitting the skirting board before the floor means either cutting it again or leaving a gap under the profile.

Removing the existing skirting board

Take it off before ordering if you can, or at the very least before cutting anything. Run a knife blade along the top joint to release the paint: without that, removal tears the wallpaper or the plaster away along the whole line. Then ease it off in small movements, without forcing it all at once.

Then look at the bare wall. There will be adhesive residue, wall plug holes, an unpainted band. Scrape, fill, sand. And check the height: if your new skirting board is lower than the old one, the mark will stay visible above it right round the room. Our profiles range from 40 to 150 mm depending on the family — there is enough scope to cover what was there.

Only two cuts, and one rule that applies to both: measure twice, cut once. A skirting board that is too long can be cut again. One that is too short is an offcut.

The straight cut

At 90°, for the joints on a straight line and for the ends that will take an end cap. Clamp the profile with the visible face upwards and let the blade do the work: forcing it marks the anodising and twists the edge. Deburr with the file, along the length.

The 45° mitre in the corners

A corner is made of two 45° cuts that meet. On paper it is simple. In a real room the corner is rarely exactly 90° — old walls in particular open or close by a degree or two. Measure the actual angle before cutting, and split it: a corner opening at 92° is cut at 46° on each side.

Watch the direction of the cut. On an internal corner, the visible face of the profile is the shorter of the two; on an external corner it is the other way round. This is the classic mistake at the first corner: the cut is perfect, it runs the wrong way, and the length is lost. Pencil onto the profile which side the wall is on before you bring the saw anywhere near.

Make your trials on an offcut. A twenty-centimetre piece cut at 45° and offered up in the corner tells you in ten seconds whether your setting is right.

The offcuts

Keep them until the end of the job, without exception. They are used to set the saw, to test an adhesive on a hidden patch of wall, to fill a short section behind a radiator, and sometimes to rescue a botched cut on the last day. A ten-centimetre offcut also remains the best sample for comparing a finish against your floor.

Gluing or screwing

Gluing gives the cleanest result: nothing shows on the face, and the profile can be taken off later without leaving holes. It requires a sound, dry, dust-free and reasonably flat wall. Follow the instructions of the manufacturer of the adhesive you are using — curing time, permitted substrates, application temperature: these values vary from one product to another and no general rule covers them.

Screwing is the safe option everywhere else: old plaster, a powdery substrate, a wall that has already been through three renovations, or simply a skirting board meant to come off again one day. Choose the wall plug to suit the substrate, not according to what is lying in the drawer: a plasterboard plug in hollow brick holds nothing.

The order of operations

The order matters more than the technique. It avoids very nearly every unpleasant surprise.

1. 1.Lay out all the lengths dry, on the floor along the walls, with nothing fixed. Check that the count adds up.
2. 2.Start with the most visible wall, the one you see as you walk in. The adjustments and the short sections will then end up behind a piece of furniture rather than in full view.
3. 3.Cut and offer up the corners before fixing anything at all. This is the moment to correct things, not once the adhesive has set.
4. 4.Fix one length at a time, checking the alignment with the spirit level after each piece.
5. 5.Then fit the accessories, then the LED strip, then the light slot cover — last of all.

The accessories

Connectors go in as the joint is made, never afterwards: they engage in the profile and cannot be slipped between two lengths that are already fixed. The same goes for the internal and external corner pieces, which dress the meeting of the two 45° cuts. End caps, for their part, close the ends and go on last.

The light slot cover clips in once the LED strip is in place and has been tested. It is supplied clear whatever the finish of the profile — that is intended, not a picking error on your order.

Aluminium moves with temperature. Do not force the lengths hard up against each other: leave the play the connector allows for. A line fitted with no expansion allowance ends up buckling or opening a joint.

The LED strip goes in once the profiles are fixed and the corners dressed. You are then working on a continuous line, which makes unrolling it far simpler.

Unroll it without pulling. A stretched strip loses contact along its copper tracks, and the fault sometimes only appears after a few weeks. Cut it only on its cut marks, never between them: cutting anywhere else kills the whole segment. Press it right down into the channel over its full length. A badly seated strip reads as a row of dots instead of a line — exactly what indirect lighting sets out to avoid.

On long runs, two transformers are often better than one: split the run in two and feed each half from one end. The voltage drop at the end of the line is reduced and the light stays even from one end of the wall to the other.

For sizing, the rule we apply is simple: the power of the strip per metre, multiplied by the number of metres, multiplied by 1.2. Then take the first model above that figure. Our transformers come in 30, 60, 100 and 150 W. That 20 % margin is not a luxury: a transformer running at full output gets hot, ages quickly and drops out at the slightest peak.

A word on colour temperature, since it is decided before installation and cannot be put right afterwards: we offer 2700 K and 3000 K. The real mistake is not choosing one rather than the other, it is having two different whites in the same room. Match the skirting board to the light sources you already have.

230 V is not your job

Here is the clear limit, and it is not negotiable. Everything on the extra-low voltage side — fitting the strip, connecting it to the transformer, plugging in the plug — is done without particular difficulty and without any authorisation. Connecting the transformer to the fixed installation of the home, on the other hand, is a job for a licensed electrician.

In Switzerland, work on a fixed electrical installation is regulated. This is not a drafting precaution: a connection made outside the rules is a safety problem, an insurance problem in the event of a claim, and a problem when the property is sold. If your skirting board is to be operated from a wall switch, fed from a junction box or integrated into a home automation system, bring in a professional. Allow for their visit in your schedule from the very start — more often than not, it is the electrician who sets the commissioning date.

The ones we see come back, in order of frequency. Not one of them is a question of talent: every one is settled at the moment of ordering or during the dry run.

• Forgetting the connectors. You count the lengths, you count the corners, and you do not count the joints on a straight line. A six-metre wall means three lengths and two connectors.
• Forgetting the external corners. The corners of the room show up on a plan; the return of a pillar or the reveal of a door shows up on site, in the middle of the job, on a Sunday.
• Undersizing the transformer. Without the 20 % margin it survives the first switch-on and gives up the following winter. Replacing it means opening everything up again wherever you hid it.
• Fitting with no expansion allowance. Lengths forced hard together end up opening a joint or lifting a piece off, usually in the middle of the longest wall.
• Misaligning the corners. Two immaculate 45° cuts on a corner that is actually 93° leave a gap that grazing light turns into a line of shadow. Measure the actual angle.
• Gluing onto a powdery or greasy wall. The adhesive holds for three weeks, then the skirting board comes away in the middle. A finger run over the wall is enough to tell.
• Cutting the LED strip away from its cut marks. The segment concerned no longer lights, and the whole of it has to be replaced.
• Fitting the light slot cover before testing the LED strip. You unclip it afterwards to check, and it never clips back quite as well.

Nobody installs an LED skirting board in an hour, and nobody spends a week on it. Here is an honest order of magnitude for a standard room, with two people, on a wall that is already finished.

• The survey and the sketch: one hour, before you even order. It is the best-invested hour of the whole job.
• Removing the old skirting board and making good the foot of the wall: allow half a day, more if the wall has to be filled and repainted.
• The dry run and the cuts: half of the installation time. That is normal, and it is exactly where you must not speed up.
• Fixing, fitting the LED strip and the accessories: the rest.
• The electrician's visit for the connection: to be booked in advance, independently of your own pace.

In practice, a first room fills a weekend at an unhurried pace. The second goes twice as fast: the saw settings are done, the method is learnt, and you finally know which way a mitre cut runs.

One last piece of common sense: do not fit it in the evening. This work is judged by eye, on alignments of a few tenths of a millimetre, and daylight is what reveals them. The first switch-on, by contrast, is best savoured after dark.