Chimney Pot Replacement & Flaunching

Pot Replacement & Flaunching Repair

The flaunching is the cement mortar bed at the top of the stack that holds the pots in place and sheds water away from the brickwork below. When it cracks — through thermal cycling, freeze-thaw movement, or the pot base working loose over time — water gets into the stack. On a job in Romford the homeowner reported damp in the bedrooms; the cause was traced back to gaps that had opened around the pot bases, letting water run straight into the brickwork. The flaunching had been failing slowly and invisibly for years. Gaps at pot bases are not visible from ground level and are easily missed until the water reaches the interior. We carry out a full inspection before recommending repair or replacement — the right approach depends on what we find when we get to the top.

We had an emergency callout on a property where two 900mm chimney pots with elephant's feet clay vented cappings were both leaning — the flaunching had already fallen from the left pot base before we arrived. Both pots came off, the stack was inspected, and they were relaid correctly with new flaunching. Tall pots need a sound base; the same applies to reclaimed lazy boy pots — the top course brickwork needs to be relaid before a 900mm pot goes back on. There is also a functional reason to consider pot height: chimneys that have been previously reduced in height — common on properties shortened in the 1960s and 70s — often develop persistent downdraught. A taller pot brings the termination above the high pressure zone during strong winds. It is worth knowing the history of a chimney before deciding on pot specification.

Pot replacement is done like-for-like wherever possible — standard terracotta, buff and red in square, round and octagonal for most domestic stacks. When pots come off, we check the lead flashing at the same time; flashing and pot repairs are natural companion jobs and combining them on one visit avoids a second access cost. On one job we had pots removed and reseated, spot pointing carried out on deteriorated joints, and lead flashing remedial works all completed from a single ridge platform visit. Period pots may need sourcing from specialist suppliers — we advise before proceeding and will not substitute without your agreement.