Poor or non-existent
drainage can lead to excessive amounts of moisture reaching the
sub-floor environs of the house.
Our soil engineer will propose a drainage system to divert water
away from the perimeter walls of the property thus decreasing the
ground water flow to the sub-floor area and the surrounding footings.
A drain is constructed terminating in a drainage pit equipped with
a sump pump or alternatively to a local storm water outlet.
The drain will approx be 150mm into the clay base and lay a 90mm
dia agricultural drain wrapped in geotextile, which will prevent
subsequent blockage due to silting.
We remove the excavated material from site and backfill the drain
with 20mm one sized aggregate to 200mm from the surface where the
ground will be restored.
Drainage is also effectively used to divert water from an area of
lateral dampness.
Lateral dampness occurs when the internal floor level is lower than
the external ground level. Lateral damp penetration from the surrounding
ground into the internal wall, can cause plaster and brick damage
through the migration of hygroscopic salts.
Before drainage works are undertaken, the plumbing junctions should
be inspected to eliminate them as a source of moisture.
In order to effectively drain and damp proof the walls from the
positive side, the surrounding earth needs to be trenched 600mm
wide down to the footings to allow sufficient working space.
After exposure of the sub-ground walls we will positively tank and
seal the sub-ground section of the walls by brush application of
cementitious membrane in slurry form to the brick faces of the walls.
This has the combined effect of sealing any gaps in the brickwork
and waterproofing in its own right.
After suitable priming we will apply an elastomeric membrane prior
to the installation of a geo-textile covered cut off drain plumbed
to SW.
The tanking will be protected with protector board and the trench
will be backfilled to 200mm from the surface with 20mm aggregate
and the original ground made good.
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