Colour Drenching: What Painting the Ceiling Too Does to Your Light

Colour drenching means painting the walls, the woodwork and the ceiling in one shade. The ceiling is the part that changes your light: drench a room in a mid shade and a fitting that shines downwards loses only 7 to 14 per cent of its light, an uplighter more than half. Choose the fittings before the paint.

Colour drenching, the interior design trend that carries one shade from the skirting boards to the ceiling, doors and radiators included, can change the character of a room over a weekend. Paint guides show the result in photographs taken in daylight. None of them says what happens in the evening, when the only light in your home comes from your fittings. The answer is not the one most people expect: it is not the darkness of the shade that decides how much light you lose, it is the direction in which your fittings send their light. This guide puts a figure on that loss, fitting by fitting, says which shades hold up overhead and what the research really shows about height. If you only want colour on the ceiling, the so-called fifth wall, the same figures apply, and we cover that case too.

What colour drenching is, and why the ceiling is the part that changes the light

One shade, every surface. A full drench covers the walls, the ceiling, the skirting boards, the architraves, the doors and often the radiators and built-in presses, in a single colour or in tones so close that the eye reads one, to create a space with no line for the eye to stop at. A tonal drench keeps the same colour family but takes the ceiling a shade or two lighter. The fifth wall is a different move altogether: white walls, and the colour on the ceiling only.

On the walls, a drench is a question of taste. On the ceiling, it is a question of light. The ceiling makes up roughly a fifth of the surfaces of a room, and it is the only one that is never hidden by furniture, curtains or a rug. Everything your fittings send upwards either comes back down off it or is lost. That is why every lighting calculation starts from a pale ceiling.

The figure that measures this is the light reflectance value, or LRV, printed beside the colour name on Irish and British paint charts: the share of light a surface sends back, on a scale from 0 to 100. Lighting standards express the same thing as a reflectance between 0 and 1. The European standard for lighting indoor work places, published in Ireland by the NSAI as I.S. EN 12464-1, asks for a ceiling between 0.70 and 0.90 and walls between 0.50 and 0.80, in other words an LRV of 70 to 90 overhead and 50 to 80 on the walls. It is written for offices rather than homes, but it says what matters: in any lighting calculation, the ceiling is the palest surface in the room. Our guide to hallway paint colours gives the LRV of each colour family on the walls, from 70 to 80 for a white down to 4 for a black. A drench takes the ceiling out of that assumption, without your light fittings being told.

What colour drenching costs in light, fitting by fitting

Lighting designers size an installation with utilisation factor tables, which give the share of a fitting’s output that actually reaches the room, according to the shape of the room and how pale its surfaces are. Read for a home-sized room, they say two opposite things.

For light sent downwards, the ceiling barely counts. Taking the ceiling from LRV 70 to LRV 30 costs 2 to 4 per cent of the useful light. Drench the walls in the same shade as well, going from pale walls at 50 to walls at 30, and the loss rises to 7 to 14 per cent: it is the walls, not the ceiling, that cost you most with this kind of fitting. Even a room painted black from floor to ceiling keeps more than three quarters of the light of a downward fitting, so a drench close to black asks for up to 30 per cent more lumens, not double. For light sent upwards, the ceiling is everything. The same drop from 70 to 30 costs 58 per cent, going from 80 to 70 already costs 15, and under a black ceiling the indirect share falls to exactly zero.

Your real loss sits between those two worlds, weighted by how much of its light your fitting sends upwards:

Your fitting	Light sent upwards	Ceiling only, LRV 70 to 30	Whole room drenched at LRV 30	Lumens to add for the drench
Flat ceiling light with a diffuser, downlights	none	3%	7 to 14%	+ 8 to 16%
Pendant or shade open at the top	about a quarter	17%	20 to 25% or more	+ 25 to 35%
Up-and-down fitting, two-way wall light	up to half	30%	a third or more	+ 50% or more
Uplighter floor lamp, cove, strip on top of a unit	almost all	58%	more than 58%	out of reach

The first row of the drench column comes straight from the tables. The others are our estimate, pro rata to the light each fitting sends upwards, and they are minimums, since darker walls also cut what the ceiling bounces back.

Take a 25 m² living room. With pale walls, we allow 200 lumens per m², or 5,000 lumens, as worked out in our guide to how many lumens you need. That guide adds 20 per cent for mid-tone walls and 40 to 50 per cent for dark ones: the safe figure for the usual mix of shaded lamps and open pendants. If every fitting in the drenched room throws its light downwards, the tables let you aim lower: about 5,400 to 5,800 lumens for a mid shade at LRV 30, or 400 to 800 lumens more, which is 3 to 7 W of extra LED. What costs you is finding out after the painter has gone.

Uplighting does not survive a dark drench

This is the one mistake that is expensive to fix. An uplighter floor lamp, cove lighting, a pendant that opens upwards, a strip hidden on top of a wardrobe: none of these lights the room. They light the ceiling, which lights the room. Once the ceiling is the light source, painting it a deep shade switches the source off, and the tables say so plainly with their zero under a black ceiling. A glass conservatory roof at night goes further still, with no ceiling at all to send the light back: our guide to conservatory lighting shows what to do instead.

Worse, the ceiling colours the light it sends back. A forest green ceiling returns a greenish light onto faces, a terracotta an orange one, and no bulb setting can correct it, because the colour is made on the bounce, not in the lamp.

Our advice is clear: under a mid or deep shade, drop the uplighting and bring the light back down. LED strip lights still earn their place in a channel that shines downwards, along a bookcase or under a shelf, but not on top of a press against a dark ceiling. An uplighter floor lamp gives way to a floor lamp with a shade, or to two table lamps. And if the room has only one ceiling point, a deep drench is the moment to think about a second source, which brings us to the fittings themselves.

The light fittings that hold up in a drenched room

• The flat ceiling light with a diffuser. It presses a disc of light against the ceiling and sends everything downwards: the safest choice under a deep shade, and the only one that loses almost nothing. A flat ceiling light with three or four bulb holders also reaches the lumens you need without hunting for an oversized bulb.
• The pendant closed by a diffuser. Same logic, one step lower, so the light is more concentrated on the table or the sofa. A frosted base and a closed top stop part of the output escaping upwards to be lost.
• Adjustable spotlights. They choose what the light hits: a bookcase, a picture, a pale piece of furniture. In a drenched room they help you win back brightness in the simplest way, by aiming at the few pale surfaces that remain. When one of them goes, the bulb you put back matters as much as the paint: our guide on how to change spotlight bulbs explains how to keep the same beam and the same white.
• The wall light that shines up and down loses half its effect: its upper beam used to draw a pale fan on a white ceiling and vanishes on a dark one. Keep it for the beam that grazes the wall, which brings out the texture of a matt drench.

Then there is contrast. A white fitting on a navy ceiling stands out like a hole; in black or brass, the same model settles into the shade. The ceiling rose, white since the house was built, gets painted with the ceiling: five minutes that change the whole picture. Several light points spread around the room beat one stronger fitting in the middle, but adding a point is electrical work. A new wall light or a second ceiling point falls under I.S. 10101, the National Rules for Electrical Installations, and should be carried out by a Registered Electrical Contractor listed with Safe Electric. Swapping a fitting on an existing point is another matter, with the power off at the fuse board.

Ceiling colours for colour drenching, and the finish

On the walls, the LRV of each colour family is in our hallway guide. Overhead, what matters is less the family than what each band of LRV still lets you do with light:

Shade on the ceiling	LRV	What still works overhead
White, soft white	70 to 80	Everything, uplighting included.
Coloured whites and pale neutrals: linen, greige, pale pink, very pale blue	55 to 75	Everything; uplighting is a little weaker at the low end.
Mid shades: pale sage, dusty pink, light ochre	about 40 to 55	Downward and mixed fittings; uplighting is weakened.
Deep shades: forest green, teal, terracotta, deep blue	about 10 to 30	Downward fittings only, spread over several points.
Near-black: navy, charcoal, black	under 15, black at 4	Downward fittings only; indirect light disappears.

Coloured whites and pale neutrals are the free drench. You gain the colour and lose almost nothing with downward fittings, and an uplighter still works, only a little weaker: the default choice for a living room you use every evening, or a room with little daylight.

Mid shades in a warm family improve in the evening, because the warmth of the light adds to the warmth of the pigment. The opposite trap waits for blues and cool greens, which lose their colour under a 2,700 K bulb: our guide to warm white vs cool white explains what each colour temperature does to a pigment. Choose the bulbs before the tin, and test a sample board on the ceiling in the evening, never on a card held upright in the shop.

Deep and near-black drenches are a deliberate choice: a cocoon in a bedroom, a dining room used at night, a small downstairs toilet. They work on two conditions, a fitting that shines downwards and several sources rather than one central point. In a room that is already dark by day, read our guide on how to brighten a dark room first.

The finish counts almost as much as the shade. On the same pigment, a soft sheen or a satin gains a few points of reflectance, but it shows every bump in an old plaster ceiling and mirrors the bulb as a bright patch right beside the fitting. Our advice: matt on the ceiling and the walls, eggshell or satinwood on the woodwork, which takes knocks and wipes clean. The slight change of sheen in one colour is also what keeps a drench from looking flat.

Does colour drenching make a room look bigger? Low and sloping ceilings

The usual promise is that a drench blurs the corners, so a small room looks bigger and a low ceiling higher. Researchers at the University of Mainz have tested it in virtual rooms, and the result is only half on its side. A lighter ceiling makes a room look higher, and so do lighter walls, the two effects adding up. The contrast between walls and ceiling, which architects and the public alike believe to be decisive, makes no difference to the height people perceive. On a coloured ceiling, its lightness is what counts; its hue has a very small effect and its saturation virtually none. And the lightness of the ceiling does not change how wide the room looks.

Read for a drench, this means the shade decides, not the technique. A pale drench, walls and ceiling both light, gives the most height of any scheme. A dark drench brings the ceiling down, whatever its colour. Since a darker ceiling does not make a room look narrower, a dark drench creates a lower, more enclosed feel rather than a smaller room, which is exactly what many people want in a bedroom.

Low ceilings. At 2.4 m or less, where a ceiling starts to feel low, keep the drench pale, or drench the walls and woodwork and take the ceiling two shades lighter in the same family. The other ways to win height are in our low ceiling lighting ideas: a lit ceiling looks further away, and a dark one cannot be lit.

Picture rails and coving. In a period room, taking the ceiling colour down to the picture rail, or 20 to 30 cm onto the walls, brings an over-high ceiling down to size. It also removes a band of pale wall exactly where a wall light throws its beam: in a room that is already dark, keep that band to 10 cm.

Sloping ceilings. In an attic conversion, the real question is where the colour stops: paint the slope and the flat ceiling in one shade, down to where they meet the upright wall, and the room reads as one volume. A pendant there lights the sloping surface from very close, and a deep shade on it switches off a whole area: two light points work better than one.

High rooms. Above 3 m, a pendant hangs well below the ceiling and sends most of its light down, and what did go up that far was largely lost anyway: this is the one case where a near-black ceiling costs very little. The choice of fitting changes too, and we cover it in our guide to vaulted ceiling lighting. Under exposed joists or beams, paint between them rather than the timber itself: you keep the pattern and limit the dark surface.

Colour drenching: frequently asked questions

Sources

• I.S. EN 12464-1, Light and lighting, lighting of work places, part 1, indoor work places: reflectance of 0.70 to 0.90 on the ceiling and 0.50 to 0.80 on the walls. National Standards Authority of Ireland
• NF C 71-121, simplified method for predetermining illuminance: utilisation factor tables by luminaire class, room index and reflectance of ceiling, walls and floor, including the class for light sent upwards. Union technique de l’électricité, AFNOR
• Oberfeld D., Hecht H., Fashion versus perception: the impact of surface lightness on the perceived dimensions of interior space, Human Factors, 2011. doi.org/10.1177/0018720811407331
• von Castell C., Hecht H., Oberfeld D., Which attribute of ceiling color influences perceived room height?, Human Factors, 2018. doi.org/10.1177/0018720818789524
• I.S. 10101, National Rules for Electrical Installations, and the register of Registered Electrical Contractors. Safe Electric, National Standards Authority of Ireland