The brick faces to a chimney stack were suffering from severe spalling and pieces of brickwork were falling onto the driveway below. The problem was widespread amongst most of the neighbouring houses and seemed to be caused by the porous bricks that were used to construct the houses, becoming saturated and freezing (freeze thaw cycle) on the exposed chimney stacks.
The defective brickwork to the chimney stack was carefully taken down and then rebuilt to the existing profile using new matching bricks laid in a sand/cement mortar tooled using a half round joint finish to match the existing work. The mortar pointing to the existing lead flashing was removed and replaced with a gun applied neutral cure silicone based sealant (leadseal) to provide a long-term flexible joint.
To help reduce the risk of any future problems caused by the freezing of saturated brickwork, Stormdry masonry cream was applied to both the new and existing brickwork on the chimney stack. Stormdry is a BBA (British Board of Agrément) approved deeply penetrating water repellent cream based on silanes and siloxanes. It lines the pores of the masonry to form a water repellent silicone matrix and because it lines the pores rather than blocking them, the masonry is still allowed to breathe.
Defective brickwork to chimney stack.
Close up of spalling bricks.
New brickwork under construction.
Brick detailing to top of chimney stack.
‘Leadseal’ silicone pointing to lead flashing.
Stormdry water repellent cream applied and soaking in.
Rebuilt chimney stack completed.