Job Example of Chimney Flashing Repair
What We Do
This chimney had leaks running into the attic. The chimney leaks were caused for two reasons: the old copper chimney flashing was tearing due to its age and the house had settled dropping the roof decking down slightly so that there was a gap between the flashing and the slate. The only solution to repair the leak in this case is to replace the flashing.
We removed the slate bordering the chimney and extracted the rusted L shaped step flashing underneath. Then we installed ice and water shield as a temporary protection measure in case it rained while we were working. Next we installed the new copper step flashing underneath each course of slate so it rested snuggly against the brick. Lastly we installed the copper chimney aprons and copper counter flashing so that water doesn’t get behind the step flashing.
When installing copper flashing it is very important to think about expansion and contraction of metal. If metal flashing is not allowed to move it will crack and cause a leak. This is why we use the European roofing technique of double folding our corners like origami where two planes of the chimney meet. Folds easily move with the change in temperature.
The counter flashing has a hem at the top so that it can be tucked into the mortar reglet, the space inbetween the brick rows, and secured using masonry screws. Generally copper and steel screws are not ideal as the two metals cause galvanic corrosion. However, the last step in this process is to fill the mortar reglet with caulk which prevents the process of oxidation.
This project took us two days to complete.