Our Process
How we repair spalled brick in Bertha
Setting the new brick with full joints
Water finds the gaps in a half-filled joint. Technical Note 46 from the Brick Industry Association describes buttering the surfaces of the surrounding brick and of the replacement completely with mortar, centering the new brick in the opening and pressing it into place, then pointing around it to make full head and bed joints.
Our crew follows that sequence on Bertha chimneys. The replacement ends up bedded on every side, which keeps it tight in the wall and gives rain no open path around it. Excess mortar is struck off with the trowel before it can smear the face of the surrounding brick.
When spalling points to something structural
The Brick Industry Association lists signs that go beyond maintenance: cracks wider than about 0.075 inch, cracks running through several bricks or in a stepped or diagonal line, widespread spalling and masonry that has moved out of plane. It advises that structural issues warrant investigation by a professional engineer.
If we see those signs on a chimney in Bertha, we tell you before replacing any bricks and explain the options, which can include an engineer's review or a partial rebuild. Replacing units one by one on a moving chimney would not last.
How deep old mortar is removed
New mortar needs a deep enough joint to hold. The National Park Service calls for raking old mortar out to at least 2 to 2 1/2 times the joint's width, which ensures an adequate bond and keeps new mortar from popping out.
Shallow raking leaves a thin skin of new mortar over old, weak material, and it fails early. Our crew rakes the joints around the replaced bricks to the proper depth by hand, taking care not to chip the edges of sound brick.
Brushing and cleanup at the end of the job
Once the joints are tooled, excess mortar and dust are brushed from the face. BIA Technical Note 20 recommends a medium-soft bristle or fiber brush and advises against steel bristles, which can leave particles that rust and stain the brick.
Our crew also clears fragments from the roof and gutters, removes the old bricks and leaves the ground below the chimney as we found it. Before we leave your Bertha home, we walk you through the repaired faces. Any bricks we reused are accounted for, and spare matched units can be left with you for future repairs if you want them.
