| Light
weight concrete
roof vaults are strong, comfortable, durable, easy to construct
and maintain, attractive, and inexpensive.Concrete is strong in
compression so concrete roofs are ideally built in shapes that are
strong in compression; shells, domes, or vaults. In my opinion,
flat concrete roofs do not represent good thinking. The only way
to make flat roofs strong enough to support themselves, and the loads
they will carry, is to use a LOT of metal reinforcing and hard,
structural concrete. Even at that, they are prone to failure. There
were some very ugly pancakes of flat concrete roofs and floors after
the last big earthquake in Mexico D.F. Vaulted roofs have much less
tendency to collapse in this manner.
Light
weight concrete vaults are easier to build and maintain and can
be build with a fraction of the metal reinforcing needed in flat
concrete roofs.
Rooms
with vaulted ceilings have a great feel in the lived-in space. This
is especially evident in low income / cost dwellings. Ceilings seem
higher than they actually are and everything feels more spacious.
Lightweight
aggregate roofs are good insulators and the thickness can vary according
to the climate. Three to four inch ( 8-10 cm) roofs are about right
for the mountains in Mexico to give you "warm in the winter and
cool in the summer".
Sealing:
Here in Mexico, we've been sealing roofs with polished, fibered
mortar. They are then, usually painted later with latex roof paint.
In harsher climates one has to resort to more exotic membranes.
Patching:
We have had excellent success patching these roofs and patches almost
always "take". Simply chisel out the offending crack with a wood
chisel, wash out the crack, paint on a cement slurry to bond, and
then polish with fibered masonry.
A well-built and maintained concrete roof should last at least 200
years.
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