When To Replace A Chimney Cap

Discover The When and How to Repair or Replace Your Chimney Cap with Island Chimney Solutions

A chimney cap is typically a large slab of concrete or mortar which sits on top of a chimney, surrounds a chimney's flue liners, and overhangs the structure of the chimney. The main purpose of a concrete cap, or crown, is to prevent rain and moisture from working its way down into the inner workings of the chimney and potentially your home.

Signs Your Chimney Cap Needs To Be Replaced:

1. Cracks in the Concrete Cap:

   
   

After years of weathering, a chimney cap will eventually start to crack and expose the flue liners to inclement weather, wreaking havoc on the overall structure of the chimney. As the fall and winter seasons set in, moisture within the cracks will freeze and expand, allowing more weather to work its way in until the cap begins to fall apart.

2. Missing or Crumbling Mortar Joints:

   
   

Check to see if the mortar between the brick or stones of your chimney is crumbling or missing altogether. Deteriorating mortar is a sign that the chimney is dealing with excess moisture and is beginning to lose its structural integrity. Replacing the cap will help to remediate the issue, however, depending on how much mortar is missing or crumbling, the chimney will have to be repointed or rebuilt entirely.

3. Spalling Bricks:

Spalling is a condition in which bricks or stones begin to fall apart due to excess moisture trapped within them. Spalling is a good sign that too much moisture is working its way into and behind the chimney itself and is not able to expel it. This is a good sign that the chimney cap is in need of being repaired or replaced, along with the bricks or stones.

How To Repair A Chimney Cap:

While there are short-term and immediate fixes that can be done, such as caulking the cracks in the cap, a much more sustainable and long-term solution would be to have it replaced. As the saying goes, out with the old and in with the new! Replacing a chimney cap entails demolishing the old one, followed by forming and pouring a new one.

Creating a form around the chimney is fairly straightforward. Cut 2x4's to length and ensure that they fully wrap around the top row of the chimney. Screw or nail them together then support the form with additional 2x4's running vertically onto a sturdy support, while also placing wedges between the brick or stone and the 2x4's for additional support. The next step is add another layer of 2x4's so that there is roughly 3" of wood around the chimney to provide an overhang for the concrete cap. Then build another raised form attached to your 2x4's so that the cap is at least 3" thick, preferably 4-5" total.

With the forms in place, it is now time to place a strip of Weather Barrier on top of the inner bricks or stones within the chimney. This will allow the concrete cap and materials beneath it to fluctuate at their own pace during the freeze and thaw cycles without separating and cracking in the process.

A layer of thin, heat-resistant Styrofoam should be wrapped around the chimney's clay flue liners for the above reasons as well. Use a piece of tape to hold the Styrofoam together. Now place and connect rebar together while keeping it raised about an inch off of the form before pouring your concrete to re-enforce it.

Now that the concrete cap is poured, allow it to cure for a week or so before removing the forms and checking out your new chimney cap!

When conducting masonry and chimney repairs, it's important to consult or hire a masonry professional before undertaking any repairs on your own. If you're located on Vancouver Island or the Victoria, BC area, contact us here at Island Chimney Solutions today for all your chimney repair and rebuild needs!

Island Chimney Solutions is a masonry and chimney repair company based in Victoria, BC which specializes in restoring and rebuilding chimneys. With over 60 years of combined chimney experience, we are well versed in all aspects of chimney and fireplace remediation. Visit our website today to learn more about what we do and our process: www.islandchimney.ca