Chimney Crowns: Right and Wrong

 Hello and welcome to my first blog entry. I have already introduced myself in the biography section of this site but my name is John Bard. The purpose of this blog is to discuss anything and everything masonry related and I will try my best to stay on topic. I will try to share some current or past projects with photos. This will be a place where the reader can gain some insight into masonry and the challenges and rewards of utilizing it in a building. I plan to bring useful information to homeowners including money saving tips and maintenance techniques as well as discussion aided by photos to help people to understand what goes wrong where and why. Masonry represents a large part of any building. As such it is a large initial investment by a building owner and can represent a huge cost in repairs and restoration prematurely if the proper techniques were not adhered to at the outset. Questions from readers area always welcome. For the first post I thought I'd talk a bit about where we are at right now in the year. Winter... Not too many masonry projects happen this time of year as it requires tarping in and heating the work area. Down south they don't have to worry about this but they have their own environmental factors to consider which will be discussed at a later date. This encapsulating of the work area and providing heat adds costs that can be simply avoided by doing the job when the season is more appropriate. And so this time of year is never too busy. So generally, winter provides me with a sort of professional development [unpaid] holiday to better myself and the business. I suppose I can't really complain about winter too much however since the season that forces me to slow down for three months out of the year, also creates much of my work for the rest of it. Let me explain. Have you ever tried to rapidly chill a drink in a glass bottle by putting it in the freezer, but then forgot about it? What happens to that bottle? It breaks from the fluid inside freezing and expanding. Simple science, but integral to understanding the beating that buildings take in a northern climate. This problem isexaccerbated by the fact that it rarely just stays below freezing forthe whole winter season. The temperature goes up and down and this freeze thaw cycling doesn't play nice with masonry. As tiny cracks develop, some of which may appear within days of doing the job due to poor technique, moisture can gain access to these cracks. This moisture sits in these little cracks just waiting for the temperature to drop below freezing and then it freezes, expands and pushes the crack surfaces apart making the little crack slightly larger. When it warms up, this moisture melts and settles again, occupying the new, slightly larger space, waiting for another freeze to expand it once again. And on and on it goes. This may seem elementary, but if left alone, it can devastate masonry structures. I provide a photo I took while standing on the top of a chimney inspecting it. You can clearly see the crown is split in pieces and water just pours in through the top of this, furthering the problem. When a chimney gets this far gone, the deterioration will be quick. Bricks and pieces of crown can fall off and damage roofs, adjacent buildings and people that may be underneath. So what is the solution? A SOLID concrete crown, not a thin concrete skim over brick like the one pictured and certainly NOT a mortar wash crown. The crown should overhang the masonry by at least 1.5”. It should have an expansion joint against all flues so that they can expand and contract as needed. And it should have a noticeable pitch on the top to drain water off the sides and prevent pooling on top. Finally, any small cracks that are caught by a yearly inspection should be sealed right away to prevent further water penetration. 

Posted on January 22, 2015 .