The lighting design in a self build is decided at first fix, not when you pick the light fittings. Before the electrician pulls a single cable, you need to know which lights go where, which ones switch and dim together, and where every switch or keypad will sit. Get those decisions onto a drawing early and the rest of the build follows it; leave them until the walls are plastered and every change means chasing, patching and repainting.
Lighting is one of those parts of a build where it is easy to spend a lot of money quickly, and hard to fix cheaply if it is wrong. The good news is that the expensive part is not the cable. Running an extra circuit or a cable to a future keypad costs very little at first fix. What costs money is finding out, after you move in, that the kitchen island and the dining table are on the same switch, or that the hall has one bright setting and nothing else.
Start with how you will live in each room
Before thinking about fittings, walk through the plans room by room and ask what happens there at different times of day. A kitchen needs bright, even light on the worktops while you cook, softer light over the table for dinner, and something low and warm for a late cup of tea. A hall and landing need enough light to be safe at night without waking the house. A living room needs to feel cosy in December and bright enough to read in.
That thinking leads naturally to layers of light rather than a single grid of downlights. Rows of downlights evenly spaced across a ceiling can make a home feel like an office. Most good residential schemes mix four kinds of light:
- General light for moving around and cleaning, often from a few well placed downlights or a pendant.
- Task light where you work: under the kitchen wall units, over the island, beside a bed for reading, at a desk.
- Accent light that picks out a feature: a stone wall, a picture, a bookcase, the staircase.
- Decorative and low level light: pendants and lamps you look at, plus step lights, plinth lights and LED tape in a ceiling cove or under joinery.
The aim is that most of the light in an evening comes from sources you do not see directly.
Decide the circuits, because that is what the cables follow
Each layer needs to be its own circuit so it can be switched and dimmed on its own. If the downlights, the island pendants and the under cabinet lights all share one feed, you will only ever have them all on or all off. Splitting them costs a few extra cables at first fix; joining them later is not possible without opening up the ceiling.
A simple way to do this is to colour code your lighting plan by circuit, then give each circuit a name the whole family will understand, such as "kitchen island" or "living room wall lights". That plan becomes the electrician's first fix drawing and, if you choose lighting control, the starting point for the scenes it will run.
Switches, keypads and the wiring behind them
Switch positions are the other half of the drawing. Put them on the opening side of each door, at the top and bottom of every stairs, and at both ends of long halls and open plan rooms.
With six or seven circuits in an open plan kitchen, separate switches soon turn into a row of plates on the wall. One neat keypad with engraved buttons for scenes such as "cooking", "dinner" and "evening" replaces that row, and it is the main reason many self builders choose a lighting control system from Lutron, Rako or Crestron.
Whatever system you choose, or even if you have not chosen yet, decide the wiring approach before first fix:
- Conventional wiring: each switch controls its own lights directly. Make sure a neutral is run to every switch position, because most smart switches and dimmers need one.
- Centrally wired: every lighting circuit runs back to a panel in a plant room or comms cabinet, and the keypads connect on a low voltage cable. This gives the most flexibility and keeps dimmers out of the walls.
- Wireless: dimmers or keypads talk by radio, which suits a renovation. In a new build you have the walls open, so it is worth running the cables anyway.
We will compare wired and wireless control in more detail in a separate guide; for a self build, our advice is simple: while the walls are open, cable for the most flexible option you might ever want. Our residential lighting page shows the kind of finished result this makes possible.
Fittings, drivers and dimming have to match
LED fittings are only as good as the driver and dimmer behind them. A downlight that flickers or buzzes when dimmed is usually a mismatch between the two. Before first fix, agree the type of dimming for each circuit, because some methods need an extra control cable alongside the mains. Fittings with remote drivers, such as LED tape and many feature lights, also need somewhere accessible to put those drivers, so a driver can be replaced in years to come without cutting open a ceiling.
Colour matters as much as brightness. Warm white of around 2,700K suits most living spaces in a home, and a high colour rendering index (90 or more) makes food, skin and timber look natural. Keep the same colour temperature through open plan areas, so that one corner does not look blue and another yellow.
Downlights and an airtight house
Many Irish self builds now aim for very low air leakage, and every hole in an airtight ceiling is a possible leak. A ceiling full of recessed downlights can undo a lot of careful work if each one pierces the airtight layer. The usual answers are a service cavity (a battened zone on the room side of the airtight membrane where cables and fittings can sit), sealed downlights designed for the purpose, and fewer, better placed fittings.
Agree this with your architect, your builder and whoever is doing the airtightness test before the ceilings go up, so the depth of the service cavity suits the fittings you have chosen. Our first fix wiring guide for self builders covers the other cables to get in while the walls are open.
Outside lights go in with the groundworks
On a one off rural house the outside matters just as much: the driveway, the paths, the front door, the patio and any trees or walls you want to light. Cables and ducts for garden lighting are cheapest to lay while the groundworks are open, so put them in now and mark the ends, even if the garden comes later.
Your lighting design checklist before first fix
| Decision | Decide by | Who needs to know |
|---|---|---|
| Light positions and layers in every room | Before tender, or before first fix at the latest | Architect, electrician |
| Circuits: which lights switch and dim together | Before first fix | Electrician, lighting control installer |
| Switch and keypad positions | Before first fix | Electrician, kitchen designer |
| Wiring approach: conventional, central or wireless | Before first fix | Electrician, lighting control installer |
| Downlight type and the service cavity depth | Before the ceilings are boarded | Architect, builder, airtightness tester |
| LED tape and joinery lighting, and where the drivers go | Before the kitchen and joinery drawings are signed off | Kitchen designer, joiner, electrician |
| Outside lights and ducts | Before the groundworks are backfilled | Groundworker, landscaper, electrician |
| Colour temperature and fittings | Before second fix | Electrician, lighting supplier |
How we help self builders with lighting
We draw the lighting plan with you: the layers in each room, the circuit schedule, the switch and keypad positions and a first fix cable list your electrician can work from. Our founder, Kieran McGuire, is an electrician, and so are a few of our team, so the drawings are made by people who know what happens on site at first fix. 1Install is a Crestron Elite Partner, and Kieran holds every Crestron certification, and we install Lutron and Rako lighting control as well, with teams covering Dublin and Cork. Our survey and design service explains how the process works, from plans to programming.
Questions we are often asked
When should I plan the lighting in my self build?
As early as you can, ideally before tender so the electrical price is based on a real design. At the very latest, the lighting plan, circuits and switch positions need to be fixed before first fix starts.
Do I need a lighting control system?
No, but if a room has more than three or four circuits, a keypad with scenes is usually easier to live with than a row of switches. Even if you are not sure, running neutrals to every switch and a cable to likely keypad positions keeps the option open.
Can my own electrician wire for lighting control?
Yes. We give your electrician the circuit schedule, keypad positions and cable list, and we can visit at first fix to check the cabling before the walls are closed. We then install and programme the system at second fix.
How many downlights should a room have?
Fewer than most people expect. Downlights work best as one layer among several, placed over worktops, walkways and features rather than in an even grid. The right number depends on the room, the ceiling height and the fittings, which is why we work it out on the plan.
Will downlights affect my airtightness test?
They can if each fitting pierces the airtight layer. A service cavity below the airtight membrane, sealed fittings and careful detailing keep the lights out of the airtight layer altogether.
What colour temperature should I choose?
Warm white, around 2,700K, suits most living spaces. Some systems let you change the colour temperature through the day, which is worth considering in kitchens and bathrooms; decide before first fix, because those fittings may need extra cabling.
While the walls are open, it is also the right time to plan your Wi-Fi. Send us your floor plans and we will mark the access points, list the Cat6 runs and price the kit, free and with no obligation, as explained in our free Wi-Fi design offer for self builders.
Book a consultation or call Dublin on 01 906 9326 or Cork on 021 202 8107.
- Log in to post comments