1. How high should a fireplace chimney be with respect to the height of the house, and what features of its design affect its efficient operation?

ANSWER: A chimney should extend at least three feet above flat roofs and at least two feet above the ridge of a peak or hip roof. Solid masonry is the most commonly used material in fireplace construction. Satisfactory performance of a chimney flue is deter­mined by its size, direction, shape, height, tightness and smoothness.

2. Is there a particular kind of mortar that should be used in fireplace construction? How is it mixed and where is it used?

ANSWER: The brick around a fireplace and flue should be laid with cement mortar, since it is more resistant than lime mortar to the action of heat and flue gases. The best to use, except on firebrick, consists of one part portland cement, one part hydrated lime, and six parts clean sand. Firebrick is best laid in fire clay.

3.What is the purpose of a damper, and how is itcon­structed?

ANSWER: A damper affords a means of regulating the draft and prevents excessive loss of heat from the room when the fire is out. It consists of a cast-iron or steel frame with a lid hinged so the width of the throat opening may be varied from a closed to a wide-open position.

4. What is the proper procedure for connecting the chim­ney to the roof so as to guard against fire, and to allow for expansion due to  temperature changes, settlement, or slight movement of the chimney during heavy winds?

ANSWER: Where the chimney passes through the roof, provide for a two-inch clearance between the wood framing and the masonry. The chimney must be flashed and counterflashed to make its junction with the roof watertight. Cor­rosion-resistant metal, such as copper, galvanized metal, zinc, aluminum, or lead is best for the counterfiashing. When tin is used, paint it well on both sides.

5. Is it necessary that a flue be lined, and if so, what are the advantages in lining it?

ANSWER: Chimneys can be built without linings, but those with linings are more efficient. When the flue is not lined, the mortar and bricks directly exposed to the action of fuel gases disintegrate. This disintegration and that occuring from changes in temperature often cause cracks in the masonry, which reduces the draft.

6. What is the proper way to build the smoke shelf?

ANSWER:
In fireplace construction, the smoke shelf should be made by setting the brickwork back at the top of the throat to the line of the flue wall for the full width of the throat. The depth can vary from six to twelve inches or more, depending on the depth of the fireplace.

7. Does the kind of fuel to be burned have anything to do with the selection of a fireplace design, and does the size of the opening affect the operation?

ANSWER: When a fireplace design is being selected, the kind of fuel to be burned should be considered; also, the design should harmonize with the room in proportion and detail. Years ago. when cordwood was plentiful, fireplaces seven feet wide and five feet high were common, but they required large amounts of fuel and were often smoky. Where cordwood is cut in half, a 30-inch width is desirable for a fireplace, but where coal is burned, the opening can be narrower. Thirty inches is a practical height for the fireplace where the width is less than six feet. The higher the opening, the greater the chance of a smoky fireplace. In general, the wider the opening the greater should be the depth.

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