Tall and exposed wallhead chimneys usually served bedroom fireplaces. The height was required to make the chimney draw well. Repairs may be required to keep chimneys dry or to stop the structure decaying.
Wallhead chimney. Repaired with new stone. Image courtesy of Historic Environment Scotland.
Wallhead chimneys suffer from all the problems found in other chimneys. In addition, they can suffer from problems with flashings and water penetration.
These chimneys may appear substantial but are actually quite slender, so stone decay can leave them with structural problems.
Cutaway drawing of wallhead chimney. Note the stay supporting the chimney and providing access for chimney sweeps.
Water penetration at chimneyheads
Water penetration often occurs with wallhead chimneys because there is limited distance between the outside and internal stonework on the top floor flats. Inspection from within the loft space can sometimes pinpoint where the water is coming in. The timbers which butt into the back of these wallhead chimneys are also vulnerable to rot damage.
Flashings
There is usually a lead flashing around the base of the chimney and a secret or hidden gutter at the back. If the flashing or gutter is defective, it does not take long for water to saturate the stone and for stains to become evident on the wall finish inside the loft.
Chimney stay flashing. This stay has been well maintained – others may be simply dangerous.
Professional help recommended?
Although the work may appear straightforward, ensure your builder or tradespeople have the skills for the job. If in any doubt, get professional help to specify and organise the repair.
