Why do shadows or unevenness appear in hidden lighting?

Usually because the tape was inserted in the wrong position, without the correct distance from the die, or without an aluminum profile that dissipates and cools properly.

Is the aluminum profile mandatory in hidden LED strip lighting?

In practice yes, because it protects the film from overheating, distortions and premature dimming.

Concealed Lighting in Plasterboard: Design, dimensions of the "cuttle" and correct placement of the LED strip

Recessed lighting is the most powerful tool in a decorator's quiver. It has the ability to transform a "cold" space into a warm, luxurious retreat, give depth to rooms and make the ceiling appear to "float".

However, as engineers, we see the same mistake all too often: Owners who have spent thousands of euros on drywall and expensive LED strips, only to see a result full of shadows, "spots" of light, or - the worst - the LED strip itself showing through the construction.

Perfect hidden lighting is not a matter of luck, but of geometry. Let's see the ideal dimensions and technical secrets for a professional result.

1. The Anatomy of Plasterboard (The "Koutelo" and the "Patura")

To have hidden lighting, we need to create a recess in the plasterboard. On the construction site, the two critical points are the "kutelo" (the vertical part that hides the tape) and the "patura" (the horizontal shelf where the tape sits).

The Ideal Dimensions:

Illustration for 1. The Anatomy of Plasterboard (The "Koutelo" and the "Patura")

Knife height (H)

It should be at least 5 to 7 cm. If it is lower, the lighting will be too "harsh" and the film will be seen from a distance. If it is higher, it will prevent the light from reaching the ceiling.

Distance from the Ceiling

The gap between the top of the box and the ceiling should be 10 to 15 cm. This gap allows the light to "breathe" and spread evenly towards the center of the room.

Platos Patouras

Usually 8 to 10 cm is enough to fit the tape and its aluminum profile.

2. Where exactly do we place the LED strip?

This is where 90% of failure or success lies. Many place the LED strip in the depth of the recess, glued to the wall. Error!

The Right Position: The LED strip should be placed as close to the tube as possible (on the outside) and facing upwards.
Why? If you put it close to the wall, you will see a strong "line" of light on the wall and no light on the ceiling. By placing it in front, the light is reflected on the ceiling and gently diffuses outwards, creating the effect of "floating".

3. The Necessary Use of Aluminum Profiles

Never stick the LED strip directly onto the drywall.

Cooling: LED strips get hot. Aluminum acts as a heat sink, doubling their lifespan.
Diffusion: The profile has a plastic cover (diffuser) that "softens" the light and prevents the effect of "dots" (dots), especially if your roof is shiny (eg pressed cement mortar or glossy paint).

4. LED Strip Selection: Lumens & Density

For recessed lighting, we are not interested in Watts, but in Lumens per meter (lm/m).

LED density: Choose strips with at least 120 LEDs per meter or the modern COB LED strips that have no gaps between the lights. So the light will appear as a single, continuous laser beam rather than a broken line.

Decorative Lighting

600 - 900 lm/m (Enough for atmosphere).

Functional Lighting (see read)

1,200 - 1,800 lm/m.

5. The secret of the "Driver" (Transformer)

As we have seen with the magnetic rails, the transformer is the component that breaks down most often.

don't "bury" him

Do not let the electrician drop the transformer into the drywall and then close it. It must be placed where you can access it (eg behind a ventilation grill or in a cabinet), otherwise in a failure you will have to tear down the structure.

Summarizing

The right recessed lighting is a balance between the hidden and the obvious. With the kutelo in the right dimensions, the tape placed towards the outside and the use of aluminum profiles, you will ensure a result that will make your house look more expensive, larger and more comfortable.

Next Step: Design is one leg. The other is the "psychology" of light. How do you know if the light should be yellowish or white? Continue to our guide: Color Temperature (Kelvin): How to choose between Warm (2700K), Natural (4000K) and Cool (6000K) light per room.

Magnetic Tracks: The Ultimate Trend of 2026 and How to Install Color Temperature (Kelvin): How to choose between Warm (2700K), Natural (4000K) and Cool (6000K) light per room Kitchen Lighting: How to properly light the worktop without shadows (LED Strips & Spots) Basic, Functional & Atmospheric Lighting (Layered Lighting): The 3-layer rule for a perfect living room

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