The roof is built by nailing 2 by 4 rafters to the inside studs of the
side wall forms, on a line 1 inch lower than the bottom of the roof.
The rafters are given the pitch desired for the roof, and are securely
fastened where they meet at the ridge. To stiffen the roof form until
the concrete has become hard tie the opposite rafters together at the
bottom (with a 1-inch strip) in the form of a capital “A.” One-inch
boards are nailed on the rafters. The cornice shown in the sketch
extending beyond the wall can be easily built by nailing a board the
width of the cornice to the tops of the outside studs of both side and
end walls. To hold the concrete in place as the roof is being built
nail a 5-inch upright strip along the outside edge of this board. Bend
the bolts projecting above the walls down to within 1 inch of the roof
boards. Spread a layer of heavy woven wire fencing over the entire
roof, allowing it to extend to the outside of the cornice. Wire the
fencing securely to the bent bolts. Place two ½-inch steel rods near
the outside of the cornice all the way around the roof, and fasten
these securely to the woven wire fencing. The roof should be made 3
inches thick and the stone used for the concrete should not be larger
than ½ inch.
[Illustration]
Mix the concrete fairly stiff and start placing it at the cornice,
working toward the ridge. Spread the concrete out in a thin layer and
then lift the woven wire fencing and the two rods in the cornice so
that the concrete is 1 inch thick below the wire. Cover the rods and
wire with more concrete to a depth of 2 inches. When finished the
roof will then be 3 inches thick, 1 inch below the wire and 2 inches
over it. Always work from the low edge of the roof and finish to the
complete depth of 3 inches at once. Imbed a width of woven wire fencing
lengthwise over the ridge of the roof 1 inch beneath the surface. The
work must be carried on without interruption. The concrete must not be
allowed to dry along an unfinished edge, as there is danger of a leak
where fresh concrete is joined to that already hard. Tamp the concrete
until moisture comes to the surface and smooth off the top of the roof
with a wooden float and steel trowel.
The forms must be left in place for at least a week and the concrete
in the roof must be protected from the sun and wind while it is
hardening. A method for doing this is described on page 26 under
SIDEWALKS.