The short answer
It can be. An aerial strapped to a stack adds weight and wind load at the top, and old steel lashings rust, expand and split brickwork. Signs include rust stains, cracked mortar around the bracket and a leaning mast. Moving the aerial to the loft or a wall mount is the usual cure, and in Aldershot's Wellesley area an aerial on a chimney facing a highway is controlled.
How an aerial harms a stack
A television aerial is held on a chimney stack by a bracket and a lashing: a steel strap or wire that wraps round the brickwork and pulls tight. The setup is simple and has been used for generations, but the load it puts on the stack is concentrated at a high, exposed point.
Weight and wind are the first issue. A mast and a large aerial array catch the wind, and the force goes straight into the top of the stack, where the brickwork is least restrained. Over years of gusts the stack flexes a little, and the mortar joints near the bracket loosen.
Lashings are the second. Steel straps rust, and rust expands as it forms, pushing against the bricks and cracking the joints beneath. Where the strap cuts into a corner, it can crush the edge of a brick. Many old lashings have rusted through and left the aerial held by little more than habit.
Drilled fixings are the third. Some brackets are bolted into the brickwork, and each hole is a way for water to enter, particularly if the fixing is not sealed.
Finally, an aerial that has come loose can pull on the pot, and the stack, as it sways, and in a storm it can drag bricks or the whole pot off. Our answer on chimney pot replacement covers what follows a failed pot.
Signs of damage to look for
You can check from the ground with binoculars, and inside from the loft. These are the signs that an aerial is causing damage.
- rust stains running down the brickwork below the lashing or bracket;
- cracked or crumbling mortar round the bracket, or a gap where the strap bears on the stack;
- a mast that leans or sways, or a bracket that has pulled away from the brick;
- the strap hanging loose, or snapped, with the aerial held by only one point;
- bricks at a corner that are chipped or crushed where the strap cuts in;
- damp or staining on the breast inside, below the line of the fixings.
None of these on its own proves harm, but together they show a stack under strain. Photograph them with the date, as with any other defect on the stack.
Do not climb up to test a lashing, and do not pull on the mast from a ladder. A stack that is already cracked can give way, and the mast is heavy.
The roofer's survey looks at the lashing, the brickwork around it and the pointing. It also covers the flaunching and the pots, since a swaying mast stresses them as well. Our guide to the cracked chimney stack answer helps you read what you find.
Moving or replacing the aerial
If the stack has taken damage, or you want to protect it, the aerial can usually go somewhere else. The options are quite simple.
Loft mounting is the most common alternative. A modern aerial can often be fixed inside the roof space, where it is out of the weather and puts no load on the stack. The signal is slightly weaker, but in many places it is perfectly good. A wall bracket on the gable end is another option, using a bracket fixed to sound masonry with a sealed fixing.
Where the aerial stays on the stack, the lashing should be renewed in stainless steel or a similar rust-resistant material, with padding where it crosses brick corners. The mast should be no bigger than needed.
Removing an aerial leaves holes and rust marks to make good. The roofer repoints where the bracket sat, fills any drilled holes and checks the flaunching and flashing. If the work is in a protected area, it should match the surrounding brickwork.
An aerial installer handles the signal side, and the roofer handles the stack. They can be booked to work together, so the new aerial goes up after the stack is repaired. The chimney repairs hub lists the masonry work that follows.
Rules in Aldershot's Wellesley area
Most aerial questions are practical, not legal. There is one local rule worth knowing in Rushmoor.
Rushmoor's Wellesley Article 4 direction in Aldershot controls antennas placed on a chimney, wall or roof slope facing a highway. Inside that area, fixing or moving an aerial in those places needs checking, and the planning team can say whether an address lies within the boundary and whether consent is needed. Rushmoor also has the Cargate direction, which deals with chimneys and flues.
These directions apply to named areas, not to Farnborough as a whole. Elsewhere, ask your council whether an Article 4 direction applies at your address. A listed house adds listed building consent for changes touching its character, and a fixing in the stack is no exception.
Ask first, before an aerial comes down or goes up. The council's website has the contact, and survey photographs help to explain what you propose.
If you are unsure, a survey gives you a view on the structure and a written price for any repair, while the planning question goes to the council.
