Wall Tie Inspection: Can You Do It Yourself?

Worried about cracks in your brickwork and wondering whether you can check the wall ties yourself? Partly. You can safely check the outside of your walls for the signs that ties are failing, and it's well worth doing. But wall ties are hidden inside the wall, so only a wall tie survey can tell you what condition they are really in.

This post covers what wall ties are, the checks you can make from the ground, what a metal detector or thermal camera can and can't tell you, and why opening up the wall is a job for a surveyor. Everything below can be done with your feet on the ground: there's no need to climb a ladder or drill into your walls.

What wall ties are and why you can't see them

Most UK houses built from around the 1920s onwards have cavity walls. That means an outer leaf (layer) of brick, a gap called the cavity, then an inner leaf of brick or block. Wall ties are metal strips or wires set into the mortar joints of both leaves. They bridge the cavity and hold the two leaves together so they act as one wall.

In homes built up to the early 1980s, ties were usually mild steel with a thin zinc coating, known as galvanised steel. Once that coating wears through, the steel rusts. Rust takes up more room than the steel it came from, so a corroding tie can force its mortar joint open and, in time, lose its grip on the outer wall.

You never see the ties themselves. What you can see is what failing ties do to the brickwork around them.

Safe checks you can make from the ground

Choose a dry day when low sun falls across the wall, as the shadows show up bulges and fine cracks. Walk round the whole house, looking at each wall from a few steps back and then close up. Look for:

• horizontal cracks along the mortar joints, repeating at regular heights, often every six rows of bricks or so, which is roughly where ties sit

• outer brickwork that bows or bulges when you look along the wall from one corner

• cracks opening at external corners, or around windows and doors

• rust-coloured staining coming out of the mortar joints

• a new gap between the top of the wall and the roof edge, where the outer wall has been pushed upwards

On rendered or painted walls the brick joints are hidden, so look instead for fine horizontal splits in the render at regular heights.

For upstairs walls, use binoculars or your phone's zoom. Please don't go up a ladder to look. Nothing you'd see up close changes what you do next, and a fall isn't worth the risk.

Keep a record you can compare

Photograph each crack with a ruler or coin beside it for scale, and write down the date. Take the same photos from the same spots every couple of months. A crack that is slowly widening matters far more than one that has looked the same for years.

Note the rough age of the house too, and whether the walls have ever had cavity wall insulation added. All of this helps a surveyor judge what's going on before they start.

What a metal detector or thermal camera can and can't tell you

A basic metal or cable detector moved slowly along a mortar joint will often beep where ties sit, so it can show whether ties seem to be there and roughly how far apart they are. It can't tell you their condition. A badly rusted tie still contains plenty of metal and usually beeps just like a sound one. A missing beep doesn't prove a tie has gone either, as cheaper detectors struggle through thick brick and render.

A thermal (infrared) camera shows warm and cold patches on a wall. That can help spot damp or gaps in insulation, but it can't show whether a tie is corroded.

So treat any reading as a rough clue, never an answer.

Why opening up the wall is a job for a surveyor

The only way to see a tie is to look inside the cavity. A surveyor usually drills a small hole in a mortar joint and passes a borescope, a thin camera on a cable, into the gap. Sometimes they carefully take out a single brick to expose a tie. We'd advise against trying this yourself, because:

• drilling in the wrong place can hit cables or pipes, or damage the face of a brick

• upper walls need safe access at height

• one hole shows one tie, and a fair picture needs several checks around the house

• telling light surface rust from serious corrosion takes experience

Hold off filling or repointing cracks before a survey, too. Fresh mortar hides the evidence a surveyor needs to see, and if the ties are still rusting, the crack will open again.

When to book a wall tie survey

Book a survey if you see horizontal cracks at regular heights, bulging brickwork, or cracks that are getting wider, especially in a home built before the 1980s. It's also sensible when a mortgage or buyer's survey flags possible wall tie problems on a house you're buying or selling.

Cracks have plenty of other causes, such as settlement, a failing lintel over a window, or normal seasonal movement. Our guide to wall tie failure signs and other causes of cracking explains how the patterns differ, but a survey is what settles it.

What happens on our wall tie survey

We look at your property first and assess the wall ties before recommending anything. You get straightforward advice based on what we find, with the scope of any work clearly explained before it goes ahead. If replacement is needed, we're members of the Wall Tie Installers Federation. As one customer put it: "Rob and Martin arrived on time for a survey and quote. Explained everything in detail."

If you'd like to know what a good survey report should cover, see do you need a wall tie survey before replacement.

If you've spotted cracks or bulging and want a clear answer about what's happening inside your walls, Cavi Clear Ltd can help from our base in Neath. Book a wall tie survey and we'll tell you plainly whether your ties need attention, and what we'd recommend if they do.