Chimney mortar removal
There are a few things you must know before starting the task of cementing a chimney crown.
Use a chisel to remove any mortar residue that might be in the area, then clean any remove any remaining pieces using a wire brush.
Making sure the flue is properly protected from any cement that might get into it is very important, because the flue is the place where all the gases and fumes pass through to get outside the chimney.
Applying the cement
First you have to mix the cement following the instructions. To get the cement on the roof, use a pail. Be sure to moisten the chimney pad you are working on before applying the cement. Keep pouring cement until there’s 1 inch of cement over the rim. After that, lay down reenforcing bars. Rebar is used to strengthen the concrete you poured.
Don’t forget to remove the flue padding only after the cement is completely dry. Apply high temperature caulk in any existing gaps and waterproof the cement.