Question answered
Is a TV aerial damaging my chimney?
The short answer
Yes, a TV aerial can damage a chimney. A mast and array catch the wind, and the bracket and strap turn that force into a steady pull on a few bricks at the top of the stack. Over the years it can open the joints, crack the flaunching and tilt the stack. A light aerial on a sound chimney may cause no harm, but a heavy one on tired brickwork is worth moving.
An aerial strapped to a chimney looks harmless, yet it sits on a long lever above the roof. In coastal wind that lever works on the brickwork every day.
How a small aerial pulls on a tall stack
Think of the aerial as a sail on a pole. The array catches the wind, the mast carries that push down to a bracket, and the bracket passes it into the brickwork through a steel strap or a pair of lugs. The longer the mast and the bigger the array, the longer the lever and the harder the pull.
The stack is already the part of the house that bears the brunt of the weather, standing clear of the ridge on the Sussex coast with nothing to shelter it. Gales off the Channel, repeated across many winters, rock the aerial back and forth. Each movement is tiny. Together they work at the mortar beds until the joints under the bracket crumble and the bricks around it begin to shift.
An old strap can also rust and swell, which forces the brick faces apart in the way that frozen water does. The damage starts small and tends to show at the top of one corner first.
Signs the aerial is already doing harm
Stand in the garden or street in good light and study the stack. Cracks that run through the mortar close to the bracket are the first clue, especially if they follow the line of the strap. Bricks that have moved out of line at the corner where the mast stands are the next. Rust stains running down the brickwork point to a corroding fixing.
Check the top of the stack as well. The flaunching, the mortar shoulder sloping down from the base of the pots, may have cracked on the weather side, and a loose or leaning mast is a sign the fixing has given. Any lean to the whole stack is serious, and we cover it separately in our page on leaning chimneys.
Inside, damp showing on the chimney breast, or a brown stain on the ceiling next to it, can follow weakened joints near the bracket letting rain through. Do not climb to inspect it.
Why the fix is often to move it
Repointing the damaged joints and fitting a new strap in the same place treats the symptom. The lever is still there, and the same brickwork is still being asked to resist it. A better answer, where the aerial is still needed, is to move the load onto something built for it.
The usual choices are a fixing to the gable wall or a bracket on the roof structure lower down, a shorter or lighter aerial, or a loft aerial where signal allows it. A wall-mounted pole spreads the force over solid masonry and brings the mast away from the stack.
Many households no longer need a roof aerial at all, because television arrives over the internet. If yours is redundant, taking it down with its bracket and making good the brick is simpler than keeping it. An aerial installer can advise on the signal side; the roofer deals with the stack.
Repairing the stack once the aerial is off
Removing a bracket leaves holes and weakened mortar. Before anything is fixed back, the old strap is cut out and the damaged joints are raked clear and repointed in a mortar that matches the brick. Our page on rendering a chimney stack explains why we avoid covering the damage with render instead.
If bricks have loosened, they are lifted and re-bedded. A cracked flaunching is cut out and laid again, so rain stops running into the stack. Work on the top few courses of a stack needs scaffolding or a tower, so the cost depends partly on access, and you receive the written figure once we have surveyed.
Timing helps. A repair in the dry months lets mortar cure properly, which is why how long chimney repairs take is worth a read before you book. Our page on repointing a chimney stack describes the usual method in more depth.
Before the next gale: sensible steps
If you have an aerial on a chimney that has not been checked for years, checking from the garden costs nothing. Use binoculars, and photograph anything that seems off. Do not tighten or adjust the strap yourself from a ladder; the brick under it may be weaker than it looks.
After a storm, look for a mast that has changed angle, a bracket that has slid, or fresh debris on the roof or ground. These are quick signs that the fixing is moving.
A survey covers the bracket, the brick around it, the flaunching and the lead at the foot of the stack, and you see pictures of each. If the aerial is the cause, you will see it in the pictures. If the chimney has a separate fault, that goes in the report instead. Once the survey is done, our written quote arrives as a single total. Our chimney work as a whole is listed on our chimney repairs page.
Aerials and chimneys: two more questions
Can I leave an aerial on a chimney that has been repointed?
You can, but you are putting the same lever back onto the same bricks. A lighter aerial, a shorter mast or a gable fixing reduces the load. If the stack has been repaired recently, a surveyor can tell you whether the brickwork is sound enough to carry the aerial again.
Who removes an old aerial, a roofer or an aerial installer?
Either can take the aerial down, but a roofer should deal with the chimney afterwards, because the holes, rusted strap and cracked joints are brickwork repairs. If you still need a signal, an aerial installer can fit a new one to a better position.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
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