Chimney Services
Sealing your Bertha chimney, from prep to final coat
Penetrating repellent versus a surface film
Clear masonry coatings fall into two families, according to Brick Industry Association Technical Note 6A. Film formers such as acrylics, urethanes and waxes leave a continuous layer on the surface. Penetrants such as silanes and siloxanes soak into the masonry, up to about 3/8 inch deep, and leave no surface film.
For an exterior chimney the difference is practical. A film can look glossy, trap moisture and eventually cloud or flake, while a penetrant changes how the pores take up water and leaves the surface looking much as it did. Our specialists use penetrating repellents on Bertha chimneys and name the product on the estimate.
Brick, stone and stucco chimneys
Each masonry material needs a product made for it. Technical Note 6A stresses selecting only coatings intended for clay brickwork when treating brick, and notes that coatings formulated for other materials may even harm brick. The ChimneySaver data sheet lists clay brick, mortar, natural stone and portland cement stucco among the surfaces it is made for.
Our specialists identify what your Bertha chimney is built from before choosing a product. A cracked stucco chimney gets stucco repair first, and a stone chimney is checked joint by joint, since a repellent protects sound surfaces and leaves open gaps exactly as they were.
Planning for reapplication
No repellent is a permanent solution, and Technical Note 6A says they will require reapplication. It also warns that reapplying a coating too early may reduce the vapor permeability of the brickwork, which works against the reason for choosing a breathable product.
We keep a record of the product, the date and the area treated on your chimney, so the next treatment is timed on evidence instead of habit. When you call later, we check how the surface is performing before recommending another coat.
Asking the brick maker when it is known
Brick is not all alike. Technical Note 6A suggests consulting the brick manufacturer, whenever possible, before selecting a coating, since the properties of each brick are unique and can affect how a coating performs.
For most homes the maker is unknown, and the test area does that job instead. Where the brick is known or unusual, our specialists take that into account when choosing the repellent for your Bertha chimney. A chimney repaired over the years may mix bricks from different sources, and the test area shows how each kind takes the product.
