Civil Engineering Reference
In-Depth Information
Roof material when harvesting the roof water
The first thing to consider when deciding on the roofing material is what is
the likely use of water harvested from the roof. For example, if the water is for human
consumption, would the water be suitable if harvested from a roof of timber shingles?
Will the shingles taint the flavour of the water or introduce more dirt than an iron roof?
Is your roof cladding likely to discharge chemicals into your water supply that might be
detrimental to your health? By what means will the harvested water be transported to
water storage areas?
PVC pipes considerations
PVC pipes to transport water to
storage tanks are cheap and easy
to fit, but is their use wise? I have
heard mention of possible health
risks in the use of PVC pipe, with
it suggested that this product
releases toxins that you would
refuse to let your neighbour's
barking dog consume. If this is
true, what of all the houses with
what is known as a sealed water
system where the water lays in the
pipes in the ground up to the
height of the inlet to the tank.
With a sealed system, water sits in
the pipe line up to the level of the
discharge pipe into the tank.
Consequently the pipes at the
house and under the ground are
always full of water up to the level of the discharge outlet into the tank (see Figure 9.7).
Figure 9.7
Sealed PVC water transport from the roof to a water tank
Variations in metal roof profiles
Metal roofing will vary in profile from one manufacturer to the next. Unless the supplier
is simply a reseller, they will have their own equipment to roll the flat sheet that is
supplied to them in coils into the shape that you purchase such as corrugated iron;
commonly known as custom orb.
Roof shingles
Roof shingles may be in the form of a tar-based product, cement sheet, slate or timber.
The most common timber shingles are made from western red cedar, however there
are many examples of early buildings with shingles made from local hardwood (see
Figure 9.8).
You will note that this property (see Figure 9.8) has at some point had corrugated
iron fitted over the top of the timber shingles to provide a more watertight roof.
