Chimney Maintenance Chimneys in old houses are frequently single skin brickwork with lime-mortar based joints and pointing. Years of external weathering and internal attack by the corrosive sulphates in flue gases can lead to gaps in the cement fillets, allowing inflammable tars to leach into the roofing material. A visual inspection of the exposed stack will highlight any obvious problem areas but hidden patches within the roof can only be dealt with when a re-ridge or re-thatch is undertaken. It's essential that when this work is in progress, the opportunity be taken to undergo any repairs and repointing necessary before the thatch is replaced. Reputable thatchers will do this as a matter of course but it's in the householder's own interest to satisfy themselves this has been done.		The lead flashing indicates the original roof line. The condition of the pointing in the area that would have been within the thatch is dangerously neglected.
Another essential maintenance procedure is getting chimneys swept. The following is taken from a publication by Dorset Fire and Rescue Service: "It is vital that flues are regularly swept. Owners should assure themselves that their sweep is experienced in the type of fire, flue and fuel combination in use. Intervals between sweeping will depend on the fuel burnt and the frequency of burning, but it must be a minimum of twice a year; once toward the end of a burning season and again prior to the start of the next to ensure a flueway clear of any obstructions, such as nests, as well as flue deposits. If wood is burnt, the frequency of sweeping should be increased." For information on the lining of chimneys, please see Multifuel and Woodburning Stoves.