or walls of a chimney should be applied direct or on
metal lath. No wood furring or lath.

The hearth, which may be of brick, stone, tile, or concrete, must be
supported by a masonry trimmer arch or similar fire-resisting
construction. Both hearth and arch should be at least twenty inches
wide and not less than two feet longer than the width of the fireplace
opening.

If the mantel is of wood, it must not be placed within eight inches of
the jambs, or twelve of the lintel.

The minimum height of chimneys above the roof line is two feet for
hip, gable, or mansard roofs, and three for flat ones.

Chimney caps must not reduce the effective draft area of flues.

In connecting the smoke pipe of a heating plant, incinerator, or water
heater to its flue in the chimney, the opening must be built with a
fire clay tile collar and the smoke pipe should not protrude into the
flue beyond the collar. Otherwise, the efficiency of the draft is
materially impaired.

In addition, home owners may have other features installed that will
do much to increase heat production of fireplaces and convenience in
the use of them. One is the steel fireplace form, built into the
chimney. This takes the place of jambs, back, throat, smoke shelf,
and smoke chamber and is so designed that behind sides and back there
is an air space opening into the room through intake and outlet vents
on either side of the fireplace. The cold air of the room is drawn
into this space, heated by radiation and returned. It acts on the
order of a hot air furnace and can be used to advantage in new
fireplaces or in old ones too much out of repair to be used without
rebuilding.

There is also the sheet-steel smoke chamber which comes complete with
throat damper and smoke shelf and is put in place above the lintel
where it extends to the point where the flue commences. A common
device for easy disposal of the ashes is the ash dump, a small
cast-iron vault located in the fireplace floor and connected with an
ash vault built in the chimney foundation. The vault is equipped with
an iron door so that the ashes may be removed once or twice a year.

So much for chimneys and fireplaces. For actual and even heating of
all parts of the house, some type of heating plant is necessary both
for comfort and economy. It is true that our forefathers lived, many
of them to a ripe old age, with only fireplaces to heat their drafty
homes and with no heat at all in their public building