Methodology & Specification for Basement Waterproofing

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20 May 2021 - 11:05, by , in Basement Waterproofing, No comments


FOSROC MEMBRANE HDPE – P: PRE-APPLIED HDPE PRESSURE SENSITIVE adhesive waterproofing membrane which bonds integrally to poured concrete slabs, remaining in place if settlement of substrate occurs



Fosroc Membrane HDPE -P is a unique membrane HDPE film pressure sensitive adhesive which allows poured concrete to bond fully with the membrane.

Fosroc Membrane HDPE-P provides water, water vapour and gas protection to water excluding structures and protects concrete from aggressive ground salts, chemicals and hydrocarbons.

Fosroc Membrane HDPE-P is supplied with a self-adhesive selvedge along one side of the roll to provide sealed laps and a comprehensive range of auxiliary products to simplify the application process.



  • Basement waterproofing protection to grades 1,2 and 3 as defined in BS8102:2009
  • To provide a vapour and waterproof membrane in building and civil engineering structures
  • Resistant to attack from chemicals and aggressive ground salts.
  • Forms a unique, integral bond to poured concrete by pressure sensitive adhesive and remaining in place if settlement of the substrate occurs
  • Simple application – no primers or protection material required
  • Inert product – no risk of a reaction with ponded waste prior to concrete being poured
  • Protects concrete from attack of chemicals, hydrocarbons and aggressive ground salts in contaminated sites.
  • Facilitates flexible construction programming
  • Full range of Fosroc hydrophilic and PVC water stops available to provide complete solution to waterproofing




FOSROC MEMBRANE HDPE- S : HDPE-S POST APPLIED Self Adhesive membrane for retaining walls with working space



Fosroc Membrane HDPE – S is a POST APPLIED flexible waterproofing high performance SELF-ADHESIVE HDPE membrane which allows concrete to be bonded fully with the membrane. It is supplied as a membrane with 1.2mm thickness of HDPE film and selfadhesive glue which is post applied to basement walls to bond fully with concrete.



  • Good bonding with concrete applied to membrane, to block water migration between membrane and the concrete.
  • Sound anti-puncture performance.
  • Excellent VOC gas barrier
  • Excellent chemical resistance -resist to acid, alkali, mold.
  • Eco-friendly material.
  • Basement waterproofing protection to grades 1,2 and 3 as defined in BS8102:2009
  • Inert product – no risk of a reaction with ponded waste prior to concrete being poured
  • Full range of Fosroc hydrophilic and PVC waterstops
  • Available to provide complete solution to waterproofing of the structure



  • Tensile Strength (ASTM D 412) : 17Mpa
  • Water Migration 0,7 Mpa, no migration
  • Breaking elongation @HDPE backing(ASTM D 412) > 500%




Application – Horizontal

  • The Fosroc Membrane HDPE-P shall be applied with sanded face uppermost to receive fresh concrete to which it will chemically adhere.
  • Laps between sheets shall be rolled to ensure good adhesion of the selvedge.
  • Roll ends or cut edges shall be sealed on the underside with Fosroc Membrane HDPE-P sealed tape/ HDPE tape sealed on the top side with a seam of Fosroc membrane HDPE-P sanded tape.
  • Alternatively heat sealing shall be used to seal roll ends or cut edges and followed by seamed sanded tape.
  • Penetrations through the membrane i.e. pipe entries, shall be made watertight using Fosroc Membrane HDPE-P with the accessories.
  • Only ancillary products of Fosroc membranes may be used in conjunction with the Fosroc membrane HDPE-P
  • Water proof joints at concave and convex corner details, cut the gusset with appropriate size and eliminate the needle holes at corners. Stick with double-face adhesive tape for self-adhesive overlapping.


Application – Vertical

  • Where Fosroc Membrane HDPE-P is applied to removable formwork; it is recommended that a minimum concrete compressive strength of 10N/mm² is reached before the formwork is stripped.
  • Mechanically fasten the membrane vertically using fasteners appropriate to the substrate with sanded face uppermost to receive fresh concrete to which it will chemically adhere. The membrane may be installed in any convenient length. Fastening can be made through the selvedge using a small and low profile head fastener so that the membrane lays flat and allows firmly rolled overlaps.
  • Ensure the underside of the succeeding sheet is clean, dry and free from contamination before attempting to overlap. Roll firmly to ensure a watertight seal.


Roll ends and cut edges

  • Overlap all roll ends and cut edges and ensure the area is clean and free from contamination and apply Fosroc membrane HDPE-P sealed tape and roll.
  • Different tapes used as accessories for Fosroc HDPE –P membrane
    – Tape: 1 Self –adhesive tape with sand used for sealing of the needle hole, repairing, overlapping reinforcement.
    – Tape:2 HDPE Tape Used for butt joints of the end laps
    – Tape:3 Self-adhesive double sided tape used for end laps
    – Tape:4 Reinforced double-side tape used for used for end side laps and overlapping of different material


Pile tops

  • Cut the Fosroc membrane HDPE-H tight around the pile top
  • Create formwork as necessary and mix and pour Supercast EPT to fully encapsulate the pile top and edges and seamlessly join to the Fosroc Membrane HDPE-P
  • Adhere a strip of Fosroc Membrane HDPE-P to the Supercast EPT sides all around the pile top and apply seam of Fosroc polyurea WCS/sanded tape/Nitoproof 600 all around the pile top.



  • (As an Optional ) Care shall be taken during soil compaction. Any chances of damaging the membrane, a 350 gsm Geotextile layer shall be provided as protective layer on membrane prior back filling.


Concreting (RCC)

  • After Membrane is placed,.
  • Concrete shall be admixed with Auramix 300/400 during batch mixing at batching plant. Fosroc Concrete Technologist shall be contacted.
  • After filling the Footing area, providing Swellable bar Supercast SW20 with Supercast SWX adhesive onto the periphery of Footing connected to Grade slab. Placed towards the positive side of the joint by leaving the 70mm concrete cover. Reference – Above system drawing.


Post concreting Application: Fosroc Membrane HDPE S

After concreting the top exposed concrete surface of footing top / Retaining wall toe top / shall be provided with Self Adhesive Fosroc Membrane HDPE S. Same shall be continued onto the existing Fosroc Membrane HDPE P


Swellable Bar application

  • Recommending Integral sealing for construction joints in concrete cast in-situ with Supercast SW 20 Swellable water bar bonded to the substrate with Supercast SWX
  • Supercast SW20 should be used to prevent the passage of water through non-movement joints in both new in-situ concrete and between new and existing concrete.

  • Supercast SW20 waterstops should be positioned to ensure that a minimum of 70 mm cover of concrete is present to accommodate pressure developed during the swelling process.
  • Supercast SW20 increases in volume in the range of up to 300% and gives a resistance to hydraulic heads of up to 100 metres.
  • It will not deteriorate under prolonged wet/ dry cycling.
  • It will be able to withstand a hydrostatic head of 100 metres (10 bars).



Termination of Fosroc Membrane HDEP P on retaining walls

  • The HDPE membrane as shown in the drawing shall be terminated on the Retaining wall 300 mm above the ground level by anchoring with Aluminium strip.
  • Followed by covering it up with epoxy mortar Nitomortar FC at 3mm thickness.
  • Nitomortar FC shall be mixed first by adding the Hardener into the Base container completely.
  • Prior to mixing individual items shall be stirred thoroughly in its container to disperse any settlement of material at the base of the container
  • Mixing shall be done by using a mixing paddle attached to a slow speed (400-500 rpm) heavy duty drill until an uniform grey colour consistency obtained.
  • Then the mixed material shall be applied over the termination zone/



Source – FOSROC Constructive Solutions


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