Civil Engineering Reference
In-Depth Information
Water and gas
In new buildings, supply and waste water pipes and gas supply pipes will normally enter
and exit the building through the floor. These are fixed in place before the floor slab is laid,
and there are no special considerations if your floor is to be made up of breathable materi-
als and includes a hempcrete insulation slab.
It is not recommended practice to run water supply pipes within hempcrete walls, as the
pipes will be difficult to get at, to find or remediate leaks, and leaking water within a wall
could cause damage to the plant-based material. However, in theory this is less of a prob-
lem with the flexible plastic pipes that are commonly used nowadays, as long as no fittings
or connectors are buried in the wall. Ideally, water pipes should be hidden under suspended
floors, but there will always be instances where water pipes supplying heating or sanitary
fittings need to travel through a wall.
Where copper pipes pass through a wall, they should run within a plastic conduit a few
millimetres bigger in diameter than the pipe, to protect the copper from the corroding al-
kaline lime in the binder, and to allow for expansion and contraction of the pipe. For plastic
pipes this should not be necessary, but always follow the manufacturer's guidelines.
If it is necessary to run water pipes through from one side of a hempcrete wall to the other,
these are best put through before the wall is cast, but if necessary they can easily be drilled
through afterwards with a core drill. The process of placing the hempcrete should be con-
sidered at the plumbing stage to ensure that the location of the pipes does not make it dif-
ficult to place the hempcrete later.
When a pipe is placed through the wall before casting, holes need to be cut in the shuttering
for that section. These holes do not need to be millimetre-accurate, as the hempcrete will
not fall out through gaps up to around 20mm wide, and if a little does get pushed out
around the pipe it is easy to scratch it back later while the hempcrete is drying out.
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