Slab
The damp proof membrane, on which the slab concrete is poured, often has to be joined. These joins must be watertight. Although the DPM is quite well separated from any underlying water - the sub-base material may be several inches deep and it may well be lying directly on expanded polystyrene sheeting, this is still one area where damp may get in. Overlap the DPM sheets at the join by at least 300mm and stick with the appropriate jointing tape.If this isn't done properly then the concrete may get underneath some of the DPM as it is poured and destroy its effectiveness.
Door thresholds
Rain has a nasty habit of getting driven under door thresholds and coming through to the inside. Even though a sealant should be used under the door frame, put an extra layer of DPC under the door frame and turn it up on the inside - holding it with the wooden flooring or screeding as in the diagram. Any rain that penetrates gets thrown back from whence it came.|
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Click on diagram for a larger view |
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