Repointing prices, the mortar choice that matters more than most people realise, and how to spot when a stack has gone past pointing and needs rebuilding.
The price range and what sits inside it
Repointing a standard domestic stack above the roof line usually costs £600 to £1,400. The stack itself is often only a day of work, so the number is dominated by getting safe access to it.
A chimney scaffold with a lift around the stack commonly accounts for £400 to £900 of that total. If a scaffold is already up for other roof work, repointing added to the same visit can be a few hundred pounds.
Old mortar is raked out to a depth of at least twice the joint width, ideally by hand on soft brick, and the joints are brushed and dampened. New mortar is pressed in in layers and finished to a weathered or bucket handle profile that sheds water.
Angle grinders speed the raking out and widen joints permanently on soft brick or stone, so on older Oxfordshire properties we work by hand where the brick demands it.
Mortar mix: the detail that decides longevity
Modern hard cement mortar on soft Victorian brick is the classic mistake. The mortar becomes stronger than the brick, so moisture is forced to evaporate through the brick face instead of the joint and the faces spall off.
Older stacks generally want a lime based mix, modern ones a sand and cement mix around 4:1 with plasticiser. Getting this right costs nothing extra at the time and is the difference between 30 years and 10.
Repointing suits a stack where the bricks are sound and only the joints have eroded. If you can rake joints out several inches with a screwdriver, if brick faces are spalled across whole courses, or if the stack has any visible lean, pointing will not fix the underlying problem.
A rebuild above the roof line typically costs £1,200 to £2,800 and includes new flaunching and usually a new lead flashing set. Our chimney repair guide sets out how those options compare.
What to do at the same time
While the scaffold is standing, it is worth renewing cracked flaunching, checking the pots are sound and seated, and looking hard at the lead apron, soakers and back gutter.
Doing all of that in one visit typically saves the cost of a second scaffold within a few years, which is the single largest avoidable expense in chimney maintenance.
How often does a chimney need repointing?
Exposed stacks in Oxfordshire generally need attention every 25 to 40 years, sooner on a very exposed elevation or where a hard cement mix was used previously.
Can a chimney be repointed from a ladder?
It should not be. Repointing needs both hands, a mortar board and time in position, which means a proper scaffold platform at stack level.
Will repointing stop damp on my chimney breast?
It helps if water was entering through open joints, but flaunching and flashing faults are more common causes. Repointing alone can leave the real route untouched.
What weather is needed for the work?
Dry conditions above about 5 degrees, with no frost forecast for a few days. Mortar that freezes before it cures will fail.
Do you match existing mortar colour?
Yes, as closely as sand and lime availability allows. On a visible period stack we will make a sample and let you see it before we point the whole thing.
Mortar crumbling out of your stack?
We will tell you whether it is a pointing job or a rebuild, and price both if the answer sits somewhere in between.
Evans Roofing & Maintenance Ltd, Witney, Oxfordshire. Call 07960 482233 for a free written quote.