What is my wall made of?

You need to know what your walls are made from because it’ll help you decide what you can hang on them and what type of fixing to use. You don’t want your £1 000 TV crashing to the floor right when the film gets to the good bit, just because you didn’t hang it the right way.

Let's get started

Materials and tools

An ear that works
Your hand
Drill (optional)
Small masonry bit (optional)
Cable detector (optional)

Walls look pretty much the same

There are three main types of walls. Unfortunately, they all look the same (kind of wallish), but you can guess the construction by rapping on the wall in several different places with your knuckles.

Solid masonry

This is good stuff. You could hang a bus on a solid masonry wall. (I’ve never tried it, and don’t recommend that anyone tries.) You’ll know a wall is solid because the rapping test produces, unsurprisingly, a dull, solid sound.

Stud wall

A framework of wood is constructed, then plasterboard is screwed onto it to make a wall. The rapping test produces a hollow, empty sound.

Dot and dab

This type of wall is a kind of cross between the previous two. A masonry wall is built, then big dollops of plaster are splatted onto the wall, which act like glue to attach plasterboard. This is an easy way to make a brick wall nice and smooth. The rapping test will produce a hollow sound in most areas (plasterboard) but a firm, solid sound in places (plasterboard with a splodge of plaster behind it).

Some things to know

Sometimes the rapping test isn’t conclusive. I’m thinking particularly in an older house, which was last plastered a hundred years ago. Often, you can find patches where the plaster is blown: it’s losing its grip on the masonry below. Although it’s a solid wall, blown plaster will give a hollow sound, which could be mistaken for a dot and dab wall. Your best guide here is the age of your house: if it was built before the late seventies, it’s a fairly safe bet that you have solid walls. After 1975 or so, dot and dab became the main method of constructing interior walls.

If you knock all over your wall and still can’t tell what it’s made from, you could try drilling into it with a small masonry bit (maybe 4 mm or so). First of all, make sure you’re not drilling in an area where there might be cables or pipes. Pick a place that you think sounds hollow. You’ll need to pay close attention to what the drill is doing.

If the drill goes in for a centimetre or so, then suddenly plunges right into the wall, then it’s likely to be a stud wall.
If the drill goes in for a centimetre or so, then plunges in a further centimetre before hitting something more solid, you probably have a dot and dab wall.
If the drill carries on drilling through something solid, it’could be any of the three types. (You might have just managed to drill right in the place where there’s a dollop of adhesive or a stud behind the board). In this case, just drill a few more holes in other places to find out.
If the drill hardly goes into the wall at all, it’s quite possible you’ve hit a screw or nail. Try drilling in another place.

Takeaways

Just knock on your wall and listen carefully.

If you can’t figure it out, you’ll probably need to drill a few holes. You can always fill them afterwards. Take care not to drill into any pipes or cables.