How to Mortar a Brick Chimney

Mortar creates a tight seal on chimneys.

Mortar bonds masonry surfaces and acts as a barrier to keep water and debris from entering a house. Filling the spaces between bricks creates a tight seal. Without the seal, water enters through the chimney and seeps into attics, walls, ceilings and basements. The water creates wood rot and encourages mold and mildew growth, threatening the structural integrity of a home and the health of its residents.

Things You'll Need

• Mortar mix
• Bucket or trough
• Spray bottle or garden hose
• Trowel
• Hawk
• Pointing trowel
• V-jointer

Instructions

1. Pour dry mortar mix into a bucket or trough; add water and mix to a pastelike consistency.

2. Spray the bricks lightly with water. Use a spray bottle or garden hose with the nozzle set to mist. If the bricks are not damp, they will draw water from the mortar and cause it to crack and crumble.

3. Dip a trowel into the mortar and scoop some onto the top of the hawk. A hawk is a flat board with a handle underneath. The board not only holds mortar but is also easy to maneuver.

4. Pick up mortar from the hawk with a pointing trowel. A pointing trowel is a small, pointed masonry trowel.

5. Press the mortar deep into a joint between the bricks. Place the hawk directly under the joint you are filling so any excess mortar will fall on it.

6. Fill all mortar joints on one side of the chimney. Place a V-jointer at the beginning of each mortar line, pressing it as you drag it along. A V-jointer is a metal masonry tool used to create a concave mortar line that forces mortar tightly between bricks. Repeat the steps on other sides of the chimney until all sides have been mortared.

Tips & Warnings

• Wear gloves and safety glasses while working with mortar.

References

• "Masonry"; Time Life Editors; 1977