A dimpled membrane (also called DPP foil or studded HDPE) is a plastic membrane with regularly spaced half-round dimples that create an air gap between the membrane and the substrate. It is mainly used to protect foundations, basements and retaining walls against moisture and to channel groundwater toward a drainage pipe.
How does a dimpled membrane work?
The dimples on the membrane form a void between the membrane and the wall. This provides:
- Drainage — water moving through the soil toward the wall can flow down through the void to a drainage pipe
- Ventilation — the void allows air circulation and helps any remaining moisture evaporate
- Protection — the membrane shields the waterproofing layer of the foundation from damage during backfilling
Applications
Dimpled membranes are commonly used for:
- Basement walls — protecting the waterproofing layer and providing drainage
- Foundation walls — moisture management for underground elements
- Retaining walls and sheet piling
- Renovation of damp walls — fitted to the inside of a basement and drained to a sump
- Under floor slabs — as a capillary break and drainage layer
- Green roofs — as a protection and drainage layer
Installation
When installing a dimpled membrane, keep the following in mind:
- Dimples toward the wall — the studs sit against the surface to be protected
- Top edge sealed — use a closure profile to keep soil out of the cavity
- Continuous down to drainage — the bottom edge must discharge into a drainage system
- Avoid puncturing — do not pierce the membrane when fixing it back
Related terms
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