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Chimney construction is one area of masonry that some more accomplished DIY enthusiasts are taking a crack at. They are attracted to the job because it is seen as a standalone project that can be completed in a reasonable timeframe. However, if you are considering taking on the job of chimney construction there are a few very important factors to consider.
While these steps may seem a little complicated when it comes to chimney construction, remember that all you are ultimately trying to achieve is a dry chimney that will not be ruined by rain. The steps below are not foolproof and are by no means everything that you need to know about weatherproof chimney construction, but they do offer good advice on two key areas of your chimney: the chimney/roof intersection and the chimney cap. The Chimney/Roof Intersection First of all, the chimney is unique in most homes as it is the only structure that is exposed to weather damage on all four sides, inside and out. If you wanted to find the most exposed and potentially at risk part of your average home, it would be difficult to find something so exposed. Therefore, it is important both at the planning stage and at the building stage to make sure that you take adequate steps to make sure you chimney is well designed. The current industry guidelines are based on years of experience and if these are followed properly, your chimney construction should provide you with a chimney that will stand up to the weather for a lifetime. The point where the roof and the chimney meet, known as the roof/chimney intersection is a vital spot in chimney construction. Making this critical spot water tight involves coordination from a number of trades. You will have to install at least four inches of base flashing on top of the roof sheathing. This should extend horizontally under the roof tiles. The flashing should then be placed inside of a raked mortar joint and properly caulked. Also, stepped flashing segments should be lapped at least three inches before sealing. If this sounds like a little bit too much hassle, you can also buy prefabricated corners which will keep your roof/chimney intersection water tight. The Chimney Cap The chimney cap is another area where the weather can get the better of you in chimney construction. Because of the risk of moisture entering the system you will not be able to simply construct the chimney cap in a mortar wash. In this area of chimney construction you will require to use either cast in place concrete, precast concrete or actual stone. You will also have to pay attention to the slope of the chimney cap so that rain water is not directed down the chimney and into the fire. While this may seem an obvious point, you’d be surprised how often it happens. |
