Why is my metal roof noisy?

Metal grows when it warms and shrinks when it cools. A long sheet in sunshine may move by a noticeable amount from morning to afternoon, and the same happens in reverse at dusk. If the sheet is free to slide, it moves quietly. If it catches on a fixing, a clip or a neighbouring sheet, the movement comes in sudden jerks, and each jerk makes a tick, a ping or a crack.

Dark coatings heat faster than pale ones, and a south-facing slope warms earlier than a north-facing one, so the ticking can travel around the building through the day. The noise is typical on sunny mornings, in the first hour after the heating comes on, and in the evening as the roof cools. It sounds alarming, yet it is often harmless.

The causes include fixings tightened so hard that they bind the sheet, clips that grip too firmly, and sheets pressed against rigid details at the ridge or eaves. Easing a tight fixing or freeing a trapped sheet will often stop it. A roofer can track down the offending spots by listening, and a quick walk-over helps.

A single sheet of profiled steel acts like a drum. Rain hits the surface and sets it vibrating, and the building below hears it. Heavy rain on a bare, uninsulated sheet can drown out conversation and make telephone calls difficult.

What reduces the noise is mass and damping. Insulation under the sheet, particularly mineral wool, soaks up vibration. A built-up roof with a liner, insulation layer and outer sheet is much quieter than a single skin. An insulated sandwich panel also helps, and our page on composite roof panels explains how they are made.

If a roof is single skin and the noise is a problem for offices, a showroom or a workshop with machinery, options include adding insulation beneath the sheets, fitting an acoustic liner or over-cladding with a heavier system. The survey will show what the structure can carry.

Wind is the main cause of a roof that rattles. A sheet whose fixings have worked loose lifts and drops in gusts. A flashing that has lost its screws flaps against the sheets. A ridge cap or gutter bracket that has come free hammers on the metal.

This kind of noise is a warning. A loose part can fail further in the next storm, and a sheet that lifts is a hazard to anyone below. Listen for where the noise comes from, and if you can see a flapping edge from the ground, note where it is.

Repair is straightforward when caught early: new fixings, refixed flashings, fresh sealant or replaced clips. If the purlins or rails behind the sheets have rusted, the fixings have nothing to hold, and the problem is larger. Our page on shop roof repairs covers similar defects on retail buildings.

Not all roof noise comes from the sheets. Water running through gutters and downpipes makes a sound of its own, especially in a big building with long pipe runs. Rapid flow in a full-bore system can gurgle, roar or bang as it picks up air.

Siphonic drainage systems are designed to run full, and they make a distinctive noise when they start to work in heavy rain. The noise is normal for the system, but it can be disturbing if no one has warned the occupiers. Our page on siphonic roof drainage explains what to expect.

Knocking and clanking in pipes can come from loose brackets or pipes that touch the structure. Cushioned brackets or fixing blocks can help. A blocked outlet that gurgles is another warning sign to deal with before the next storm.

The remedy follows the cause. For expansion noise, the fix is freeing the binding point. For rain noise, the fix is added mass or insulation. For loose parts, the fix is repair. For drainage noise, it is clearing, re-bracketing or adjusting the system.

It helps to tell us when you hear the noise: at sunrise, in the rain, in the wind, or when the heating starts. The pattern points to the cause. Photographs of any visible movement are useful. Expect each fix to deal with one kind of noise only: freeing a bound sheet will not quieten rain, and added insulation will not stop a flapping flashing.

Where the roof is close to being worn out, noisy sheets with failing fixings and rust may be a sign that replacement is nearer than repair. Our guide to commercial landlord roof repairs sets out how responsibility for a roof like that is usually worked out between landlord and tenant.

We start with a survey, inside and out. We listen, look at the fixings and flashings, check the condition of the sheets, and photograph the defects. If the noise is expansion, we tell you, along with whether it needs any action. If something is loose, we tell you what it is.

A written quote follows the survey, alongside photographs of the roof as it stands. We would rather cure the noise with a small repair than sell you a bigger job. Our page on dilapidations and roof repairs at lease end may help if a lease is a factor.

Once the work is finished the site is left clear and the waste goes with us. Workmanship is guaranteed in writing for 10 years, and our commercial roofing page lists what else we do.