How to Make an Old Brick Chimney Safe for a Wood Burning Stove

Inspect the chimney visually by using a ladder to get up on the roof. Secure the ladder safely before climbing. Look for cracked or missing pieces of mortar between the bricks. If the chimney is deteriorating on the outside, there is a good chance the inside of the chimney also is in need of repair.

Fill in the joints between the bricks with fresh mortar. Mix mortar in a bucket with just enough water to make a thick mixture that holds its shape. Pour the mortar into a mortar bag and squeeze into any open joints. Smooth out the seam with a jointer tool, making a slight but smooth indent along the joint. Allow the mortar to dry for at least 3 days before using the chimney.

Check on the flue liner of the chimney. Typically, this is a fireclay liner about 5/8 inch thick with a 1/2-inch gap from the brick of the chimney. Inspect the flue from the inside of the home as well as from the roof with a strong flashlight to see if there are any cracks. When you see a solid flue, or a metal liner you are in luck and can operate your wood stove normally. If the flue liner has cracks, you must reline the chimney before using a wood stove.

Add a new metal liner that reaches from the stove to the top of the chimney, if there are problems with your old chimney liner. This will ensure that the hot gases leave your house safely without leaking through bad mortar joints. Cut a section of chimney liner to match your chimney's height using tin snips. Wrap the liner with liner insulation and then wrap the insulation with wire mesh. All of these items come in a chimney liner kit with detailed instructions. Drop the liner into your chimney, securing the top by sliding the top plate over the pipe and then tightening the liner's hose clamp. Have a helper get the liner to the roof and then pull it through the chimney from inside the house.

Cover the top of the liner with a metal cap, sliding the cap over the collar on the liner plate. Tighten the cap's hose clamp to secure it in place. This cap will keep birds from nesting in the liner as well as keep rain water out of the liner.

Install your wood stove to vent through your fireplace. Clamp the pipe from the back of the stove onto the chimney liner pipe with another hose clamp.