By far the most attractive recessed downlights — mainly they're practically invisible. Plaster-in downlights have become very popular, and with good reason. They don't interrupt the planes of the ceiling, apart from the internal aperture.
Note: Plaster-in downlights and trimless downlights are basically interchangeable. For the purpose of streamlining, I'll refer to these beautiful downlights as 'Plaster-In'. There are nuanced differences between the two, but for the purpose of this blog, the info applies to both plaster-in downlights and trimless downlights.
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Bulb or dedicated LED?
You'll need to decide between a version that takes a replaceable bulb (typically a GU10 lamp) or a dedicated LED version. I strongly recommend the bulb version — and yes, many electricians would argue with me on this.
Here's my reasoning: with a GU10 fitting, the carcass is fixed in place but the light source can be changed down the line as technology evolves. Dedicated LED versions have a shelf life, and while interchangeable LED modules exist, there's a real risk that if the supply chain changes the chip in any way, the replacement will look slightly different to the rest of your lights — and then you'd have to change them all. Think of the mess. No thanks.
Watch out for deep scallops
One thing that sets plaster-in downlights apart from many other options is how high up the light source sits. This means you'll get deeper scallops (shadows) on walls if the light is grazing a wall or cupboard. To avoid harsh shadows, either position the light in the middle of the space so the beam doesn't hit anything on the way down, or place it right up against the wall or cupboard to close the shadow gap.
They're more affordable than you think
Plaster-in downlights may look expensive, but there are genuinely affordable options available. One of my favourites sells for around £22 excluding the bulb — I don't stock it because my price would be too high, but I'm happy to recommend it. Get in touch and I'll point you in the right direction.
Key things to know before you buy plaster-in downlights:
Important: Many plaster-in downlights must be fitted at first fix (but not always) — before the ceiling is boarded and skimmed. Plan ahead!
- Ceiling board depth — check to see if the fitting requires compatibility with your plasterboard thickness - most require a maximum and minimum plasterboard depth between 12cm - 26cm. There are some plaster-in downlights that have flexible metal mounting 'wing's which can adapt to any board depth by mounting directly onto the surface of the plasterboard, not within the ceiling cut out. If the metal wings mount inside the ceiling void, there will likely be min/max plasterboard depths in order to align the light properly with the surface.
- Ceiling void depth - make sure there's enough height above the ceiling to keep the electrics clear of insulation, etc. A plaster-in downlight may require more ceiling depth than average recessed downlights. Typically, a depth of 150mm will suffice.
- Joists, pipes and insulation — check there's nothing in the way above the ceiling before cutting out the hole, such as joists, pipes or insulation and make sure that the fitting is clear on the sides as well, by a typical minimum of 50mm (check the manufacturer's instructions). Make sure there is room for to the sides if the fitting has extended metal 'wings' which can double the length of the fitting inside the ceiling.
- Allow for extra long internal widths - Some plaster-in downlights have long metal flanges (picture a person standing with their arms out to the side - the arms, or wings, are to keep the light from falling through the hole and allow for secure mounting). For example, there is a plaster-in downlight with a small opening - 73mm, but with an internal length of 135mm. You need to make sure there's room inside the ceiling to accommodate the long flange without hitting a joist, etc. Not all lights have this design, some have round metal flanges and some have short square ones.
- Skilled plasterer required — the skim around the fitting needs to be done carefully, not rushed. The whole point is that the fitting looks seamless with the ceiling. No wrinkles, no waves.
- ALWAYS CHECK WITH YOUR ELECTRICIAN BEFORE BUYING - Once you find one that you like, show your electrician the specification and/or instructions to make sure that they can install the lights before you buy them.
Typical installation steps
Always follow the manufacturer's instructions, this is a rough guide and by no means to be taken as actual instructions.
- Cable in place — leave about 30 cm of spare cable to allow the fitting to be pulled down for inspection if needed
- Check ceiling void clearance — a good rule of thumb is 150mm minimum clearance to the top and 50mm to the sides
- Board the ceiling
- Cut the hole — measure carefully for the correct size and shape
- Insert the fitting into the hole
- Screw the wings to the board
- Plaster and skim
- Connect the light fitting
