Home » Systems » Systems for Waterproofing » Negative Side Waterproofing


Negative Side Waterproofing

Negative Side Waterproofing



  • All surfaces to be waterproofed must be firm, clean, dry, sound and smooth. All grease, oil, wax, curing compounds, loose material, paint and any other contaminants must be removed, surfaces must be pointed flush and surface defects repaired.

  • External corners to be waterproofed must be bevelled to ensure a smooth transition of membrane from vertical to horizontal surfaces.


  • Repair all surface defects on masonry surfaces and install a 40mm x 40 mm cove to all vertical and horizontal internal corners, using Sika Grout 212 HP. SikaGrout-212 HP is a ready mixed, high quality, Portland cement that expands in two stages to counteract the shrinkage normally associated with Portland cement grouts.

  • Install a gun-able water stop around all penetrations. The water stop must be packed in between at least a 50 mm cover of SikaGrout-212 HP. Gun-able water stop products are caulk grade (gun-able), single component swelling pastes used to stop water infiltration through concrete construction joints

  • Apply WPA 160 to all non-porous surfaces such as PVC and metal pipes. WPA 160 is a specialised solvent free primer designed for enhancing the adhesion of subsequent membranes, adhesives, toppings and decorative finishes over porous or non-porous substrates.

  • If the area to be waterproofed is subject to continuous water seepage, seal off the flow using Sika Plug, then continue as described below. Sika Plug is a chloride free, ready for use powder, which becomes a powerful, fast setting water plug when mixed with water

  • Install a reinforcement layer over all coves using Sikalastic 1K. Sikalastic 1K is a one component, flexible, fibre reinforced mortar, ideal for waterproofing surfaces subject to flexural strain.

  • Install two coats of Sikalastic 1K ensuring that a minimum dry film thickness of at least 3mm is achieved.