Running Coaxial Cable Without Damaging Your Home

Plan the Route Before You Pick Up a Drill

The single biggest cause of damage when running coaxial cable is deciding the route as you go. Spend twenty minutes with a pencil and a notepad first, and you will avoid most of the heartache. Walk the property from the aerial, dish or external antenna right through to the room where your router or TV lives, and sketch the shortest sensible path that keeps the cable out of harm's way.

Good routes tend to use voids you already have: lofts, cavity walls, floor joist spaces, and cupboard corners. Bad routes cut diagonally across a beautifully papered wall or run down the face of a rendered cottage. As a rule, a cable should be invisible from the moment it enters the building, and it should never be somewhere it can be stood on, shut in a door, or pinched behind furniture.

• Keep runs as short as practical, but never at the cost of quality. A tidy 30-metre run beats a crushed 12-metre one.
• Avoid running parallel to mains wiring for more than a metre or so, and cross mains cables at right angles where you must.
• Think about where water collects, where heat rises, and where feet, mowers and livestock travel.

Getting Through Lofts and Insulation

Lofts are forgiving, but they are not maintenance-free. Lay boards or a sheet of ply across the joists to spread your weight, and take a torch even in daylight. Clip the cable along the sides of joists rather than letting it lie loose, and keep it clear of downlight fittings, hot water cylinders, boiler flues and anything that gets hot enough to soften the foam dielectric inside the cable.

Modern lofts are often buried under 270mm or more of mineral wool. Burying coaxial cable under insulation is not ideal. The insulation traps heat and, in a loft that already bakes in summer, the cable's plastic sheath and foam core age faster. Lift the wool, run the cable along the joist, then lay the wool back over it if you must, but leave a little air around the cable wherever you can. If you are routing a cable that also carries power — for an inline amplifier, say — keep it well clear of insulation entirely.

Walls, Floors and the Things You Cannot See

Before any drill touches a wall, use a cable and pipe detector. Even then, treat every wall with suspicion, especially in older rural properties where previous owners have been creative. Look for the tell-tale signs: a line of filler, a row of filled screw holes, a slight bulge in the plasterboard.

Drill from the outside in for external entries, angling the bit very slightly downwards so any water that finds its way in runs back out. A 10mm hole is plenty for most coaxial cable, leaving room for a grommet or a blob of silicone sealant afterwards. Always deburr the hole and fit a rubber grommet where the cable passes through metal, or the sharp edge will slowly saw through the sheath.

Inside, lift floorboards rather than cutting them, and refit them the same way round. If you must drill through joists, keep the hole in the middle third of the depth, no more than a quarter of the joist's depth in diameter, and at least three diameters away from the ends. Never notch a joist. Along skirting boards, a length of self-adhesive mini trunking or a discreet staple-free clip every 300mm will hold the cable neatly without crushing it.

Protect the Cable Itself

Coaxial cable is not indestructible. The foam dielectric inside is easily deformed, and once the geometry of the cable changes, the signal suffers. Respect the minimum bend radius — for a typical WF100-style cable, that is around 50mm, or roughly ten times the cable diameter. A single tight kink at a corner can cost you more signal than 20 metres of extra cable.

Use proper cable clips rather than nails, and never hammer a clip so hard that it bites into the sheath. On external runs, use UV-stable cable or run it inside conduit. Where the cable enters a connector, fit a drip loop so water runs off the outside of the cable rather than tracking into the plug. Seal external connections with self-amalgamating tape, and use compression F-connectors rather than twist-on ones wherever the weather can reach them.

Rural Properties Need Extra Thought

Stone walls, thatch, timber frames and long distances between buildings all change the job. Thatch in particular demands respect: it is a fire risk, and drilling into it or running a cable through it is a job for someone who has done it before. In stone or cob walls, chase carefully and use conduit, because the cable will need protection from damp and from the abrasive surface. For outbuildings and barns, run the cable in a duct or armoured conduit, buried at least 450mm deep with warning tape above it if it crosses open ground.

Finally, test before you seal. Connect everything up, check signal strength and quality at the far end, and only then fill holes, refit boards and tidy away. It is far easier to re-run a cable through an open loft than through a freshly decorated room. If the run is long, or the signal still looks weak, an inline amplifier or a better-sited external antenna will do more good than any amount of cable tidying. Take your time, keep the cable gentle, and your home will barely know it is there.