Chimney Height Affects Draft
Chimneys and fireplaces have a long history of heating humanity in the cold winter months. The height of the chimney is very important when it comes to the functionality of the heating appliance or fireplace. However, some chimneys like the one pictured here bares concern of not just functionality problems, but also safety hazards. While traditional fireplaces are aesthetically pleasing, it is crucial that they are constructed up to code.
A properly functioning fireplace requires a chimney with a proper draft. Draft is the air movement through the face of the fireplace and up the chimney. A poor drafting chimney will cause smoke to expel out of the fireplace and into the room. The scale of area of the fireplace and flue area work together to create a good draft, but distance is also very important. An increased distance between the hot fire and the cool winter air will increase the draft of the fireplace. A short chimney will be very hard to light a fire without smoke expelling into the living space.
Proper Chimney Height
A perfectly clean fireplace with zero cracks in the flue tile means nothing if the top of the chimney is too close to the roof or surrounding structure. In this situation as pictured, the chimney is very unsafe in that regard. At one time, we imagine th chimney pictured above was constructed to be the correct height over the roof. However, a roof top patio was added and constructed directly next to the chimney. In no circumstance should this fireplace be used. Creosote will build up on the side of the building and in the event of a chimney fire, this could cause serious damage to the home.
Code stipulates the chimney be no less than three feet above the roof where it exits the roof and be two feet higher than any portion of the roof that is within ten feet away. This is called the 10 foot-3 foot-2 foot rule.
Solving Short Chimney Syndrome
So, how do we solve these functionality and safety issues with this chimney? The answer is simple in this situation: extend the top of the chimney. There are a few ways we could do that. The first way would be to use brick and mortar to extend the chimney height. Getting the bricks to match might be difficult though. Another way would be to extend the chimney with a specialty stainless steel flue extender. Standard flue extenders are offered in two height sizes, 22" and 34" heights. If you need to go even taller than that, a properly sized Class A chimney pipe Anchor Plate can be adapted to the flue allowing a Class A chimney pipe to extend the flue.
Luckily, it appears this homeowner does not use this chimney. If they decide to sell their home, the home inspection is surely going to note that this is not a functioning fireplace. When bringing fire into a home, safety and functionally are the most important things to take into consideration before lighting a fire.