Civil Engineering Reference
In-Depth Information
To prevent condensation from pipes, all pipes must be fed through the straw bale wall
within an insulated sleeve. This will prevent condensation between the bales and the
surface of the pipe. While it is possible to insert the sleeves following the construction of
the walls, it is much easier to fit them during the construction of the wall. Your plumber
will be able to provide you with the details of where pipes will penetrate straw bale walls.
In single-storey house construction there are very few wall penetrations required, as most
will go through the floor.
Feeding pipes through a sleeve
When installing 100 mm pipe it could be fed through 150 mm PVC and insulated
between the sleeve and pipe. Allow sufficient length for the sleeve to reach from one side
of the bale wall to the other with approximately 20 mm additional length at either end.
This will enable the application of the first and second coat of render to finish roughly
level with the face of the sleeve. The cavity between the 100 mm and 150 mm pipe could
be filled with spray-in foam (see Figure 13.1). This will secure the pipe in position while
providing an insulation barrier between the pipes and thereby eliminate condensation. If
you are avoiding the use of foam the cavity could be filled with wadding, however be sure
to seal the ends well with the render to avoid vermin penetration. If the space between
the pipes is not filled appropriately it will also form a bridge for heat transfer from the
inside to the outside the building. Needless to say, a 50 mm pipe could be fed through
100 mm sleeve and so on.
Figure 13.1
100 mm sewer pipe through 150 mm pipe with expanding foam sealant
Water feed lines can be sleeved with Aeroflex foam rubber inserted into 38 mm PVC
pipe (see Figure 13.2).
