Should you repair the chimney while the roof is being replaced?

Getting to a chimney stack is the costly part of any chimney repair. On a two-storey house the stack stands well above the eaves, and working from a ladder at that height is not safe. MyBuilder's scaffolding guide, updated in August 2026, puts high-level chimney scaffolding at £400 to £900, and its chimney repair guide, from the same month, gives a repointing range of £500 to £2,000. Both are national figures for stand-alone jobs, so read them as context only. The real figure for your house depends on the height of the stack, the number of pots, the condition of the brick and the access, and the written quote settles it once the survey is done.

When a re-roof already has scaffold around the whole house, the stack can be reached from the roof edge or from an extra lift above the ridge. What is left to pay for is then mostly labour and materials. That is the reason to ask about the chimney at the survey, rather than finding it ten months later when the access becomes a separate bill again.

The stack is normally finished soon after the old covering comes off, and before new battens and tiles are fixed around it. Working from the top down, the pots are checked and re-bedded. The flaunching is the sloped mortar collar that holds each pot and throws rain away from it; it is often the first part to crack, and it is renewed. Brickwork is repointed where the joints have perished, and an old stack built in lime is repointed in a compatible mortar, which our note on lime mortar chimneys explains.

Lower down, the flashing is the band of lead that weatherproofs the joint between stack and roof. A soaker is a small folded lead sheet tucked beneath the tiles or slates alongside. They are lifted with the covering, then replaced in new lead that is let into the brick joints and dressed over the tiles. The back gutter behind the stack, which steers water round it, is rebuilt at the same time. Once the lead is in and the stack is sound, the new covering is fixed up to it.

Old lead is stiff and work-hardened after decades of expanding and shrinking. Lift it and it often splits along the folds, so reusing it invites a leak within a year. New lead costs little beside the labour of getting back up to the stack, which is why replacing it is the norm. Sheet lead is sold by code, a measure of thickness. According to Leadworx, Code 4 is widely used for general flashing, and Code 5 is common where more weight is wanted. The choice depends on the run length and how exposed the stack is.

A figure may help here. MyJobQuote's September 2026 guide puts full replacement of chimney leadwork at £350 to £460 without scaffolding and £700 to £920 with it. The gap between the two shows how much of the cost is access, and a re-roof pays that already. Our page on chimney flashing goes further into the detail.

If the fireplace has been closed for years, a re-roof is a natural time to ask whether the stack is needed at all. Taking down only the part above the roof is one job. Taking out the breast in the rooms below is a different job again, and the Planning Portal says Building Regulations approval will always apply to that, because breasts are part of the structure. Should the neighbour share that wall, there is a party wall notice to serve too, and GOV.UK says notice goes to the neighbour between 2 months and a year ahead of the work.

Lowering or capping a stack also has to allow for ventilation of any flue still in use, and for the neighbour on the other side of a shared stack. Raise all of this at the survey. Our page on chimney removal covers the process, and nothing comes down until the consent position is clear.

Because the stack is worked on first, the programme matters. Fresh mortar needs time to take up before the roofers load the area, and lead cannot be dressed until the brickwork is ready to receive it. Wet weather delays both. Our page on fascias and gutters during a re-roof explains how the eaves are scheduled around the same scaffold, and the note on the best time to re-roof covers the seasons.

If you have noticed loose bricks, a leaning stack or a damp patch on an upstairs chimney wall, send photographs with the enquiry form. The survey then looks at the stack from above as well as from the garden, and the quote that follows in writing includes pictures of your own chimney. A sound stack is simply left alone. Our workmanship is guaranteed for 10 years, in writing, and old mortar and broken brick go away with the scaffold. Ask at the survey about a chimney cowl or pot replacement too, since both are quick once the access is there. The rest of the job is on the main roof replacement page.