How do I run cables and pipes inside a stud wall?
Where to drill through a stud, how to protect a cable from a future screw, and the planning that means you never have to open the wall again.
- Difficulty
- intermediate
- Time
- 2 hr
- Read
- 5 min
- Safety
- warning
Short answer
Drill through the centre of the stud's depth, not near the edges, and keep the holes in a consistent line. Where a cable runs closer than 50mm to a face, fit a steel protection plate over the stud or run it in conduit. Decide every socket, switch, light, radiator and bracket position before you board, and photograph the finished frame.
Do this first
The whole point of a stud wall is that it is hollow, and the moment it is boarded that advantage disappears. Everything that will ever run inside it has to be there before the board goes on, and it has to be positioned so that the next person to put a screw in the wall does not hit it.
Safety
What you'll need
- A flat bit or auger of the right size
- Steel protection plates or metal conduit
- Grommets for cable holes (optional)
- Cable clips and a cable detector
- Pipe clips and pipe insulation (optional)
- Back boxes for sockets and switches
Step by step
- Plan every outlet before you drill anything.Socket and switch positions and heights, light points, a radiator's pipe drops, a TV bracket's cable route, network points, a thermostat. Mark them on the frame in pencil, stand back and check the heights look right in the room.
- Drill through the middle of the stud's depth.Centred between the two faces, so the cable is as far from a screw as it can be. A hole near an edge also weakens the stud considerably more than one in the centre.
- Keep the holes in a line.Set a consistent height and mark it across the studs before drilling, so cables run level and you know afterwards exactly where the run is. Random heights make the run impossible to predict later.
- Drill oversize and fit grommets.A hole a few millimetres larger than the cable means it is not chafing on a sharp edge as the timber moves, and a rubber grommet or a smooth-bored hole protects the sheath.
- Protect any cable running within 50mm of a face.This is the rule that matters. A steel plate screwed over the stud at the cable position, or the cable run in earthed metal conduit, protects it from a screw or nail driven into the wall later.
- Use the safe zones for vertical and horizontal runs.Runs to an accessory should go straight up, down or across from it, within the recognised zones — which is what makes a cable's position predictable to the next person with a drill. Diagonal runs across a wall are the reason detectors exist.
- Fit back boxes to the studs, not to the board.A metal or plastic box screwed to a stud or to a noggin is solid forever. A dry-lining box gripped to the board alone works loose as the socket is used.
- Keep water services away from cables.Separate runs where you can, and never run a cable directly beneath a pipe joint. Insulate pipes in the wall so they do not sweat and so they are quieter.
- Leave slack.A generous loop at each outlet. Cable pulled tight has nothing left if a box has to move, and slack costs nothing now.
- Photograph everything before boarding.The whole wall, with a tape measure in shot, showing every cable run, pipe, noggin and box. This single photograph is worth more than any detector for the rest of the wall's life.
Tips
- Fit noggins for future fixings at the same time as running the services, so you know the fixing points and the cable runs are not in the same place.
- Run a spare draw cord or an empty conduit through the wall while it is open. Adding a network cable or a speaker cable later then takes minutes instead of a day.
- Where a pipe has to cross a stud, notch the top edge rather than drilling if the pipe is large — but understand that notching weakens a stud considerably more than a centred hole, and there are limits on where and how deep.
- Cables generating heat should not be buried in insulation. If you are filling the void with mineral wool, think about where the cable sits within it.
Common mistakes
- Drilling near the edge of the stud — It weakens the timber where it matters most, and it puts the cable within reach of a screw driven from either face.
- Running cables diagonally across a wall — Nobody can predict where they are. Detectors are unreliable and the next person to hang a picture finds the cable the hard way.
- Skipping protection plates — They cost pennies and they are what stops a screw reaching a cable. This is not an optional refinement.
- Boarding before deciding where the sockets go — Adding a socket to a boarded wall means cutting, fishing a cable, patching and redecorating.
- Burying a connection — Joints must remain accessible. A junction sealed inside a wall cannot be inspected or repaired.
Questions people ask
Am I allowed to do this myself?
Physically routing cable inside a wall you are building is not the regulated part; making the electrical connections and adding or altering circuits is, and some of that is notifiable. The usual arrangement is that a competent DIYer frames the wall and runs the containment, and an electrician does the connections and certifies the work.
How far apart should cable holes be from pipe holes?
As far as the wall allows, and never with a cable directly under a compression joint or a soldered joint. Where they must cross, keep them apart vertically and protect the cable.
Can I run a waste pipe in a stud wall?
Only if the studs are deep enough — a 40mm waste with clips and a fall needs considerably more depth than a 63mm stud provides, which is why bathroom partitions are usually built deeper. Plan the wall depth around the largest thing going in it.