Builder’s Opening
Builder's Opening
Builder's Opening
Fireplaces are the source of much misinformation. All too often what people think is the 'original fireplace' is actually the builder's opening, in which a fireplace has to be built. The reason for this is that fires are very damaging, and it is best to have those parts most likely to suffer damage able to be removed without affecting the structural integrity of the chimney.
Fireplace Construction
Fireplaces are all too often lined with house bricks set in cement, often faced or covered with plaster. The high heat involved will almost always damage all three types of materials, so it is best to use fire bricks set in fire clay if a single piece fireback is unsuitable.
Wood in the Fireplace Area
It sounds pointless to mention it, but wood, or anything inflammable in the fireplace area is unwise, and that includes mantelpiece/fireplace surrounds made of wood that overlap or even approach the fireplace opening too closely. A lot of people assume that a wood lintel for a fireplace is ok, because they were used in the old fashioned inglenooks, but they overlook the inverse square law. Put simply, if you halve the distance to a heat source, you quadruple the heat falling on it per square inch. In an inglenook, the wood lintel is 6 feet away from the fire. On a small modern fire, it can be a foot away, which means it can get 20 times as hot. Building Regulations approved document J is a useful source of information on this and other matters as it is a list of all the standards, dimensions that everything that fires and chimneys have to conform to.