Air Gap Method: Dependence of water removal on RH in room and height of floor air gap

Using the Air Gap Method inside building constructions, harmful water can be dried out. The method ventilates air gaps inside walls and floors with an air flow driven by convection aided by a heating cable in the vertical air gap.This study is performed in combined floor and wall constructions with air gaps within and with a heating cable in the vertical air gap. All surfaces of the air gap are covered with polystyrene plastic to avoid leakage into the construction. Wet gypsum boards that are weighed at start and end of experiment are used to measure the dry out process.Three different heights of the floor air gap, 25 mm, 15 mm and 5 mm are investigated. The influences of the RH in the surrounding room and of the wetness of the gypsum boards are also investigated.It is shown that the height of the floor air gap has a great impact on the rate of drying. The optimal height is less than 25 mm and somewhere between 15 and 5 mm.

► By the Air Gap Method in building constructions harmful water can be dried out.
► It is built by connected air gaps inside walls and floors.
► A heating cable in the vertical air gap gives a convective air flow.
► The height of the floor air gap has a great impact on the rate of drying.
► Optimal height of floor air gap is close to 15 mm.