Fitting heating films over existing plasterboard

The case where the ceiling is already finished

The boards are up, taped and sometimes painted, and the client wants to add heating without stripping it all out. That can be done, but it imposes a simple rule: the films go below the existing boards, and then receive a second facing.

Why you do not fit above

Placing the heating element behind a board already in place would mean taking the ceiling down, which is exactly what was being avoided. Fitting below keeps the existing ceiling intact and allows work from inside the room.

What it costs in height

A second facing plus the air gap needed. That is the only real drawback of the method, and it is measured on site before the solution is proposed, particularly in a home whose height is already marginal.

The value of the old ceiling

It becomes the back of the plenum. Combined with reflective insulation it forms a closed wall behind the heated surface, which fulfils exactly the function a new substrate would have been asked for.

Locating the wiring

The existing ceiling already contains boxes, cables and sometimes light points. Locating them before any fixing avoids drilling into a live circuit, and that check takes less time than putting it right.

When the method is not justified

If the existing ceiling is in poor condition, if it is not flat, or if the height does not allow the extra thickness. In those three cases a full strip out finally costs less than working around a substrate that is a problem.

The fitting technique is set out on the dedicated page, and connection on the heating films page.