Building defects database - Shared chimney stack

Record details

© Copyright Philip Santo	(a) The fire places in this semi-detached house were located centrally on a dividing wall between the ground floor rooms, so in the roof space above the chimney breasts the flues were contained within this angled masonry section, leading to a shared chimney stack above the party wall. See also image (d) below.
© Copyright Philip Santo	(b) After the ground floor dividing wall and fireplaces had been removed some years previously there was slight downward settlement of the retained first floor wall and chimney breasts onto the presumed support at ground floor ceiling level. This downward movement imposed tension stress on the angled flue brickwork in the roof space, causing this visible separation across the brickwork, just below the junction with the party wall.
© Copyright Philip Santo	(c) The eccentric loading on the now-unsupported angled column of flue brickwork caused it to pivot sideways towards the party wall. Fortunately the column fell against the party wall after only moving a few centimetres and before it built up any momentum, and there it came to rest. This pivoting movement (to the right in this image) caused this second crack to open at the base of the angled section.
© Copyright Philip Santo	(d) The whole section of the flue brickwork between the crack at the base and the crack at the top near the party wall was resting against the party wall, as it had apparently been doing for many years.
© Copyright Philip Santo	(e) The maximum crack width reflected both the downward movement when the separation occurred and the additional angled opening created as the column pivoted to the right (see also image (b), seen from the opposite side). If the sideways movement had been very much greater before coming into contact with the party wall the consequences for the occupants might have been very serious.
© Copyright Philip Santo	(f) Within the ground and first floor living accommodation there was virtually no evidence of any of the downwards movement which followed the removal of the ground floor dividing wall and chimney breasts. The most obvious was this unremarkable minor cracking to plasterwork beside the first floor chimney breast, providing no clue about the unusual state of affairs in the roof space immediately above.