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Sub Floor Ventilation |
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Suspended timber floors are prone to deterioration by high humidity levels in the space between the floor and the exposed soil
beneath. Even during long hot summer weather and severe drought conditions when water table levels have dropped significantly,
water vapour still migrates upward through the soil and evaporates into the atmosphere. When trapped by perimeter walls and a
timber, (even suspended concrete floors), this vapour will saturate timber floors, (including joists and bearers), as well as
the surrounding masonry. Vapour penetration may seep through to completely soak the masonry, bricks and mortar as well as some
sedimentary stone.
Please notice the lack of efflorescence, (
surface salt deposits ), in both pictures, the increased height of
dampness between the vents under the window sill in picture (1)and the dry masonry at the base of the wall in picture (2).
Condensation can also occur under suspended floors where the temperature of humid air in the floor space is lowered by cold air moving
in through ventilators and water is then condensed on the underside of floor. This will often induce timber decay of the wooden floor.
Timber floors built on battens over a concrete floor are not immune to ventilation problems and are also prone to damaging humidity levels
in the space between the timber flooring and the concrete base.
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