How to repair an old and damaged chimney?

Chimneys are very important to place on top in the priority of maintaining. They are often neglected at summer time when they are not in use. Regular inspection helps in keeping those chimneys clean and well functioning. Any failure in keeping up the maintenance of these old chimneys brings issues and needs urgent repair. But how do you repair an old and damaged chimney?

There are different types of chimney repairs, and each problem has a different method of repairing the chimney. Below is an overview of some of the most common chimney repairs and replacement techniques and how to repair them.

Readjust the chimney: The mortar holds the chimney on the surrounding bricks. Over time, the mortar may loosen and crumble, causing the stack to come off the brick. When applying grout, damaged or brittle mortar is scraped off and replaced with new mortar.
Use a grout scraper to scrape loose or damaged grout. Leave the good grout as it is. Spray the garden hose on the bricks and leave it for 30 minutes. Make sure the roof is dry before proceeding.

Mix a batch of new mortar: This should have the same consistency as peanut butter. Use a pointed trowel to push the mortar into the open joint to match the existing mortar. Then smooth the grout with the tack pointing tool.

Caulking around the chimney and crown: The gap between the chimney and the crown can be a problem as water can seep into the house. To solve this problem, you need to use a wire brush to remove dirt, loose grout, and moss from the grout.
Then use a caulking gun and a tube of hot grout to completely fill the gap with the full bead of joint compound. Repair cracks in the crown.

Patch hairline crack: Hairline cracks can be repaired with a waterproofing agent. This is a liquid substance that can penetrate cracks in the hairline. This solution seals cracks and surrounding areas and makes the entire area waterproof.
Use a spatula to scrape loose particles, but make sure the cracks do not grow any further. Then apply the impregnating agent to the area with a brush without dilution. Two coats are sufficient to completely seal the area.

Fix broken bricks: If individual chimney bricks have small cracks, these are usually easy to repair with hot mortar and caulking guns.
Clean the cracks with the edge of the putty knife and remove any loose parts. Clean the cracks completely with a wire brush. Push the hot mortar into the crack as much as possible. Wipe the grout with your gloved fingers to make it smooth.

Estimate cost of chimney repairing

The average cost of replacing a chimney flue or liner is around £ 800 to £ 1,200, depending on the size of the chimney and the quality of the product used to complete the work.

If the chimney needs to be readjusted, this can cost around £ 500 to £ 1,000, depending on the size and accessibility of the chimney.

Best time to consider replacement of chimney

If you own a relatively modern home, you may be able to repair the chimney. Chimney replacement is usually only necessary if the chimney represents a structural burden. For example, if the chimney is tilted to one side, this indicates an unstable subsoil that cannot support the chimney. This is a danger that needs to be addressed immediately, as a tilted base can collapse without additional warning.