Proper Chimney Crown Design Characteristics

Chimney crowns look so simple. However, being around for centuries they have evolved to become fine works of engineering, that if constructed properly, can survive decades and still be efficient. In this article we cover some very important characteristics of chimney crowns.

Proper Chimney Crown Design Characteristics

Slope:

A concrete chimney crown should have a slope. This is the high point of the crown. Think of an umbrella design – this is the same mindset. You are trying to limit the exposure of moisture to whatever you want to protect below it. The slope does not need to be exaggerated by any means, but it should let water runoff easily during heavy rainfall and not pool up at all. In Chicago especially, there is heavy precipitation so ultimately a good slope should last many years without much deterioration.

Overhang:

The slope extending down from the chimney flues leads to the outermost edges of the crown, the overhang. Every aspect of a properly poured chimney crown is very important. Think of an umbrella – you would like it to extend past your body so to minimize how wet you get. The overhang is the second part to proper water runoff. As we know, any moisture freezing and thawing in the bricks, mortar, flue liners, etc. is detrimental to a chimneys health. The overhang aims to combat this by eliminating runoff of moisture onto the bricks.

So how much is enough overhang? The common consensus, backed by years of trial and error, research, and more, is that the ideal distance from any brick to the outermost edge of a concrete chimney crown is 2”. This distance is ideal for structural integrity of the crown and for prevention of long term water damage to the bricks below. Too much overhang would still allow for good runoff of water but it would weaken the concrete itself. It is a delicate balance that is struck here.

Drip edge:

A drip edge installed underneath the overhanging chimney crown edge is a minimal touch that aids in water runoff. Water does not perfectly runoff the crown. Some moisture still hooks at the bottom most corners of the concrete and hooks towards the brick. The drop edge counters this additional water and redirects from making contact with the bricks.

Reinforcement:

The reinforcement is metal installed during the pouring of the concrete crown. Wire mesh for smaller crowns does the job of adding lifespan. For larger caps, in both width and height, require rebar inside the crown for proper support. If you have ever seen a concrete sidewalk or driveway being poured, it has the same characteristics supporting it from movement and to strengthen it.

Coast to Coast Masonry, Local Chicago Chimney Crown Experts

At Coast to Coast Masonry Group (CTC), we repair, restore, protect, and preserve masonry including brick, stone, and concrete. Whether it is a crumbling chimney, a broken glass block window, or parapet wall our expert masons are here to help. We use the latest masonry technology techniques to restore brick and protect your home.

We at CTC Masonry are the complete solution to your masonry and chimney needs. We highly value our clients and seek to gain their confidence by offering the highest level of customized chimney services and masonry products at a competitive price.

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