Waterproofing
Basement & below-grade waterproofing
The BestMem GroundAD 110 HDPE membrane, with a sanded face and adhesive-lapped seams, bonds directly to the concrete to waterproof and protect below-grade structures.
Public technical guidance
This page is selection and sequencing guidance, not a project method statement. The current product TDS, approved design, site assessment and trial application take precedence; structural anchors, cracks, water-retaining structures and other safety-critical work require qualified technical review.
Applicable for
- Basement slabs and walls of commercial and industrial buildings.
- Traffic tunnels for expressway or commercial rail systems.
- Structures requiring protection between the underground and exposed sections.
Bestmix material system
BestMem GroundAD 110
HDPE waterproofing membrane with a sanded face and adhesive-lapped seams, offering high elongation and elasticity.
Consumption: By waterproofed surface area, with 80 mm overlaps at the edgesBestAcc H-Tapes 1
Single-sided HDPE adhesive tape for the membrane, used to treat inner/outer corners.
Consumption: By linear meter, used at inner/outer cornersBestAcc H-Tapes 2
Double-sided HDPE adhesive tape for the membrane, securing seams and junctions.
Consumption: By linear meter of seams and junctionsSubstrate requirements
- Clean the concrete surface free of dust, excess mortar, voids and protruding sharp objects.
- The surface must be flat and clean, with no ponding water or running water.
- Remove all loose materials or protruding sharp objects from the surface.
Step-by-step procedure
- 1
Horizontal application
Unroll BestMem GroundAD 110 with the adhesive face up, align adjacent rolls with an 80 mm overlap at the edges and press firmly with a roller to maximise adhesion. At butt seams, bond the two membrane layers with BestAcc H-Tapes 2 double-sided tape.
- 2
Vertical application
Before stripping the formwork, the concrete must reach a minimum compressive strength of 10 N/mm². Fix the membrane vertically with mechanical fasteners (screws), adhesive face outward to bond the freshly poured concrete, leaving the membrane extended above the rebar for subsequent work.
- 3
Inner corners
Measure, cut and fit a membrane piece into the re-entrant corner at the junction; secure it with BestAcc H-Tapes 2 double-sided tape at the base of the vertical face and roll down the seam. Cut BestAcc H-Tapes 1 single-sided tape into a cone shape and apply it to the recess.
- 4
Outer corners
Measure, cut and fit a membrane piece onto the external corner at the junction; secure it with BestAcc H-Tapes 2 double-sided tape at the base of the vertical face and roll down the seam. Cut single-sided tape into a figure-8 shape and apply it to the protruding corners.
- 5
Pile heads
Measure, cut and wrap the membrane around the pile head, leaving about a 30 mm margin at the junction with the floor slab. Notch the lap and fix it firmly with BestAcc H-Tapes 2 double-sided tape using a roller.
BestMem GroundAD 110 is measured by the waterproofed surface area plus 80 mm edge overlaps; BestAcc H-Tapes 1 and H-Tapes 2 are measured by the linear length of seams and junctions.
Common questions
Which product should I use for basement and below-grade waterproofing?
Use the BestMem GroundAD 110 pre-applied HDPE membrane for basement slabs and walls, combined with BestAcc H-Tapes 1 and H-Tapes 2 to treat seams, corners and pile heads.
What overlap and concrete requirements apply for vertical application?
Membrane sheets overlap 80 mm at the edges. For vertical application, the concrete must reach a minimum compressive strength of 10 N/mm² before the formwork is removed.
Is the membrane installed before or after pouring concrete?
BestMem GroundAD 110 is a pre-applied membrane: it is installed first with the adhesive face outward so the freshly poured concrete bonds directly to it, creating a watertight, fully bonded seal that stops groundwater from migrating between the membrane and the structure.
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