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Masonry fireplace proportionMasonry fireplace proportions that should be adhered to in the design of a masonry fireplace if it is to work properly. The inspector will not ascertain whether the specifications have been adhered to or whether the fireplace smokes into the building. Please refer to the seller of the property for information with regard to the fireplace operation. Even a well-designed fireplace will often smoke. One frequent cause of smoking in a home fireplace is a lack of sufficient combustion air, especially with a roaring fire going. Such a fire sends a large quantity of air up the chimney. This air drawn out of the room in that the fireplace is located and must be replaced, either through an open door or window, or by means of natural infiltration from the outside. This is why the newest fireplace designs include ducts that go directly outside (sometimes called outside air kits) for intake of combustion air. If too little air gets into the room, the fire will not have sufficient draft, and smoke will back up into the room. If you suspect this problem, try opening a window in the room a few inches. The smoking may stop very quickly. Sometimes the owner of the building does not know how to build a proper wood fire. Assuming that you start with seasoned wood green wood will smoke a lot more easily and will make it much harder to keep the fire going the first thing you should do is make sure the damper is wide open. Then spread a layer of crumpled newspaper over the floor of the fireplace, under the andirons (or inside the fire basket if you use one), and cover this with a layer of wood kindling, spreading the sticks or dried TWIgs so that they crisscross each other on top of the paper. On top of this kindling you build the actual fire, using three logs. Place the largest log near the back wall but not quite touching it and the second log about 2 to 3 inches in front of this one; then place another layer of kindling on top of these two logs so that it bridges the two logs. Put the third log on top between the other two so that the three logs form a sort of open pyramid. Before starting a fire, light a large sheet of newspaper and hold it up near the throat of the fireplace, just under the damper. When it is almost burned up and flaming well, drop it on top of the logs and immediately light the layer of crumpled paper under the wood with another match. The reason for holding the flaming paper up in the throat of the fireplace is to warm the air in the chimney and start an upward draft which will help get the fire started and keep it from smoking before the chimney heats. Probably the most frequent of all reasons that a fireplace smokes is that the fireplace opening is too large for the size of the flue, or the damper is too low (too close to the top of the opening). If the measurements of your fireplace opening do seem larger than they should be or if you suspect that the damper is too low (not up inside the throat), then here is a simple test you can run to see if the problem can be easily corrected: get a fire going in the fireplace, then hold a sheet of metal or a piece of water-soaked plywood across the top of the fireplace opening. It should be about 12 to 1 inches wide and at least 6 to inches longer than the width of the fireplace opening. Starting at the very top, slide this piece slowly downward to give the effect of a decreased opening height for the fireplace. Keep moving it down till the smoking stops. This will indicate the correct size for the opening. You can then have a permanent metal hood or shield built across the top to close off the opening by this amount, or you can build the opening up from the bottom by placing extra rows of fire brick on the floor of the fireplace. Another frequent cause of smoking is down drafts, especially when a stiff wind is blowing. This condition can be due to the fact that the chimney is not high enough in relation to nearby dormers, peaks, or other structural parts of the house, or it can be caused by an overhanging tree branch that may be interfering with a free flow of air past the top of the chimney. Generally, the chimney should project at least 3 feet above a flat roof, and at least 2 feet higher than the ridge of a sloping roof when that ridge, or any other part of the roof, is less than 10 feet from the chimney. Large trees or overhanging branches should also be at least 10 feet away if they are taller than the chimney. Very often the simplest cure is just to extend the chimney higher, either by actually building the brickwork higher or by adding sections of metal chimney pipe to the top. The extension should have a flue which is at least as large as the original flue inside the chimney.
File last updated February 08, 2012 * Copyright © 2012 All rights reserved by: Accurate Inspections, Inc. A New Jersey home inspection firm 56 Woodland Drive, Woodland Park (formerly West Paterson) NJ 07424 973-812-5100 providing New Jersey Certified Home Inspections in NJ, by New Jersey Licensed home inspectors. Inspector of record Michael Del Greco, New Jersey Home Inspector License GI 0121.
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