If your chimney in March is deteriorating and you are waiting for a roofer to start the rebuild, knowing what you should do in the meantime - and what you absolutely should not attempt yourself - can prevent a manageable problem from becoming a costly one.
A chimney rebuild means removing the existing stack down to just above the roofline and constructing it fresh from that point up. Matching bricks are laid in the correct bond, new lead flashings are dressed into the brickwork around the stack, a damp proof course is installed at the base of the rebuilt section, and new flaunching is formed at the top to hold the chimney pot.
The cost of a full chimney rebuild for a standard residential stack typically falls between £1,500 and £3,500, depending on the size and height of the chimney, the brick type needed, and the scaffold arrangement.
Chimney rebuilds are not jobs that can usually be started the day you call. Scaffold needs to be arranged, bricks need to be sourced and matched, and in colder months the work needs to be timed around frost - fresh mortar must not freeze within the first 24 to 48 hours or it will fail to cure properly and the bond between bricks will be weak from the outset. This means there will often be a gap between an agreed job and the start date.
That waiting period is important to manage correctly. A chimney that is already deteriorating is vulnerable, and certain things will make it worse. Knowing what you can safely do - and what you cannot - makes a real difference.
There are practical steps that are safe to take from inside the house or from the ground, without getting onto the roof.
The temptation to do something while waiting is understandable, but several common DIY attempts create more problems than they solve on a chimney that is waiting for a professional rebuild.
Do not apply sealant or waterproof paint to the brickwork. Brush-applied sealants trap moisture inside the brickwork rather than allowing it to evaporate. On older porous bricks, sealed-in moisture that freezes will push the brick face off (spalling), making the structural situation worse before the roofer arrives. The correct fix is sound mortar and properly fitted lead, not a surface coating.
Do not attempt to fill open mortar joints with filler or mastic from a ladder. Reaching mortar joints at chimney height from a ladder is neither safe nor effective. Filler and mastic applied from distance cannot be packed properly into the joint, and mastic in particular shrinks and cracks within a couple of years, holding water rather than excluding it. It will need to be raked out again before proper repointing is done, adding unnecessary work.
Do not remove loose bricks yourself. If a brick is visibly loose or has shifted, leave it in place. Removing it without the full scaffold and replacement material available can destabilise adjacent bricks and in extreme cases cause a partial collapse. Loose bricks at height are a falling hazard to people below, not something to handle from a ladder.
Do not cap the chimney pot with a temporary cover of your own making. A poorly fitted cover can be dislodged by wind and fall onto the roof or the ground below. It can also create a dead-air pocket inside the flue that accelerates condensation on the interior brickwork. If the flue needs temporary protection, discuss it with your roofer, who can arrange an appropriate solution as part of the job setup.
Do not get onto the roof. This is the most important point. A deteriorating chimney stack is unpredictable - brickwork that looks stable from a distance may be loose at close range. Working near it without the correct scaffold and fall protection is a serious safety risk. Roof tiles are also fragile underfoot and easily broken, which creates a separate leak risk if displaced.
If the chimney visibly shifts or partial collapse occurs while you are waiting, call your roofer immediately and ask whether emergency works are needed to make the structure safe. In some cases a temporary scaffold can be erected ahead of the planned start date to stabilise or isolate the affected section. If brickwork falls and damages the roof covering, that is a separate repair job that needs addressing at the same time as the rebuild.
A common problem in periods of cold weather is for previously marginal chimneys to deteriorate rapidly when frost gets into open joints. If a freeze is forecast and your chimney is already in poor condition, let your roofer know.
Once the rebuild is finished, the new mortar needs time to cure before the chimney is used. Your roofer will advise on the appropriate drying period, which is typically at least a week in reasonable conditions and longer in cold or damp weather. If the chimney serves a working fireplace or stove, have it swept and checked by a qualified chimney sweep before lighting the first fire.
Inspect the new work from the ground after the scaffold comes down. The brickwork should be neat, the mortar joints uniform, and the lead flashings lying flat and dressed tightly to the brickwork. If anything looks out of place, raise it with your contractor before you settle the final payment.
Ely Roofers carry out chimney rebuilds in March and the surrounding area, including Ely, Chatteris, Stretham, Little Thetford and nearby villages. Call us to arrange a proper chimney survey so we can assess what is needed and give you a written price before any work begins.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
