Frequently Asked Questions

How are Proofex 10 sheet joints made and what quality checks are used to confirm the joint is watertight?

The joints between adjacent sheets of Proofex 10 are the most critical elements of the waterproofing system — a well-installed continuous field of membrane can still fail if the lap joints are not correctly fused and sealed. For torch-applied Proofex 10, the lap joint is made by heating the underside of the overlapping sheet edge with a gas torch flame until the bituminous compound softens and flows slightly (the surfacing mineral granule, if present, should disappear into the molten bitumen at the lap area, indicating correct heating temperature), then immediately pressing and rolling the heated lap onto the sheet below with a firm roller or gloved hand pressure. The lap width must be a minimum of 100 mm — the 100 mm overlap provides sufficient length for the fused joint to resist the design hydrostatic water pressure. The quality check for a correctly made torch-fused lap joint is the visual observation of a thin bead of molten bitumen extruding from the front edge of the lap as the overlap is rolled — this bead indicates that the full thickness of bitumen in the lap has been heated to the correct temperature and has flowed to fill the lap void completely. If no bead extrudes, the joint may be insufficiently heated and the lap is not fully fused. After installation and before backfilling, all joints should be visually inspected for the presence of the bead, for any areas where the edge of the lap has lifted or is not fully bonded, and for any damage (tears, perforations) in the membrane field. Defects should be repaired with patch pieces of Proofex 10 extending 100 mm in all directions beyond the defect before backfilling proceeds.

Can Proofex 10 be used on a basement retaining wall that retains a significant head of groundwater during the monsoon season in India?

Proofex 10 is designed and tested for positive-side waterproofing of concrete structures below ground, including retaining walls subject to hydrostatic pressure from groundwater. The hydrostatic head that Proofex 10 can resist depends on the specific product grade and the installation quality — the waterproofing performance is tested and rated in metres head of water as specified in the technical data sheet. For a typical basement in Delhi NCR or other North Indian locations where the seasonal water table rises to within 1 to 3 metres of the ground surface during the monsoon season (June to September), a Proofex 10 sheet membrane with the appropriate hydrostatic resistance rating is suitable for the retaining wall waterproofing. The key installation requirements for reliable performance under hydrostatic pressure are: the concrete wall must be sound and free of cracks wider than 0.5 mm before the membrane is applied; the membrane must be applied as a continuous, fully bonded system without lifting, bubbling, or delaminated areas; all penetrations (pipes, conduits, anchor bolts) through the membrane must be sealed with compatible flashing tape or liquid-applied membrane collar seals; and the membrane must extend at least 150 to 200 mm above the design maximum groundwater level at the top of the retaining wall. The drainage and gradient design of the basement perimeter drainage system (drainage mat, perforated drainage pipe, and sump) should be coordinated with the membrane waterproofing design to manage the groundwater pressure and reduce the sustained hydrostatic head on the membrane during the monsoon.

What is the difference between Proofex 10 and Proofex Engage for basement waterproofing and when should each be used?

Proofex 10 and Proofex Engage are both membrane waterproofing systems from Fosroc for below-ground concrete structures, but they are installed at different stages of the construction sequence and work by different bonding mechanisms. Proofex 10 is a post-applied membrane — it is applied to the outer face of the already-constructed basement wall after the concrete has been cast and the formwork struck, before the soil is backfilled. The membrane adheres to the concrete surface by torch fusion or cold adhesive bonding. Proofex Engage is a pre-applied membrane — it is installed before the concrete is poured, with the self-adhesive face placed toward the formwork or the formation surface. When the concrete is poured, it contacts and bonds to the adhesive face of the Proofex Engage, creating a structural concrete-to-membrane bond. Post-applied Proofex 10 is used when the outside face of the basement wall is accessible after construction (which requires the construction sequence to allow exterior access before backfilling — typically achieved by constructing the basement with temporary soil support such as sheet piles or secant piles set back from the wall face). Pre-applied Proofex Engage is used when the basement wall is constructed in a contiguous pile or diaphragm wall where the permanent wall is also the temporary support, and no exterior access to the structural wall face is possible after construction. For new basements in the majority of urban Indian sites where basement walls are constructed against sheet pile or secant pile temporary support and exterior access is available, either system can be used — Proofex 10 is generally simpler to apply and inspect before backfilling; Proofex Engage provides the superior structural bond that prevents lateral water migration under the membrane.