Monday, November 12, 2007

Building Chimneys, 1870

Every chimney ought, if practicable, to extend clear to the bottom of the cellar, and rest there on a substantial foundation, covered with a broad, flat stone, to prevent the absorption of dampness by the bricks. There is always more or less danger from fire, when a stove-pipe is passed through the floors into the attic, and thence into the chimney. Stove-pipes must often be placed in close proximity to some joist, stud, or other wood-work. Then, in very cold weather, when hot fires must be kept up day and night, the thin pipe often becomes red-hot, so that heated timber even one foot from the pipe, will frequently take fire. But, if the stove-pipe enters the chimney in the same room where the stove is situated, all danger from fire will be cut off. Besides this, the expense of a chimney from the bottom of the cellar to the top of a house will be but a trifle more than the cost of six-inch pipe extending the same distance. Indeed, where bricks are cheap, a chimney will cost less than pipe. And when several stoves are to be connected with a chimney, were the pipes of each one to be extended to the attic story, the aggregate expense would be more than double the expense of a good brick chimney.

Another consideration in favor of the independent foundation of a chimney in the cellar is, that the great superincumbent weight may not injure the wall in any way. More than this, when a chimney rests on a foundation in the attic, or even in an upper room, during long and severe storms such a large volume of water usually falls directly into the chimney that the bricks at the bottom become thoroughly saturated. Consequently the surplus water soaks down through the wall below; whereas, if the chimney had extended to the bottom of the cellar, the walls would not have been injured by the great fall of rain.

When chimneys are built on a platform in the attic, or when they are carried up from the floor through upper rooms, they should always stand on a flat stone, or a wide, sound plank or board, which will catch the water that would otherwise work down and injure the wall. Such foundation stone or plank should slant a trifle, so as to carry the water down between the siding and the side wall, where it will do less injury than if it fell directly on the wall.

The size of a chimney is another important consideration. Flues should not be too large nor too small. If the smoke of only one stove is to be discharged into the chimney, a flue about the size of one and a half bricks or two bricks will be sufficient. If the smoke of four stoves is to pass out of one chimney,the flue should be equal to 160 square inches; or to a flue 12 inches by 13 square. Still, if the flue were twice as large, the draught would be about the same as if the flue were 12 x 13 inches square. But the most attractive form of a chimney-top is to make the flue twice as long as the width. The form of the chimney below the roof may be made square, or of an oblong form, to suit the taste or convenience of the builder, where space is an important object.

1 comment:

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