Keeping the basement dry for decades: waterproofing the NCRTC Quarters in Ashram, Delhi

A basement is the part of a building you hope never to think about. Once the structure is finished, backfilled and occupied, nobody wants to dig it up again. That is why waterproofing below ground has to be right the first time.
For the NCRTC quarters at Ashram, New Delhi, TECHNONICOL waterproofed 12,000 m² of basement structures with two membranes, each chosen for the surface it protects: ULTRABASE PA (sand finish) for the horizontal raft and ULTRAFLEX SA HDPE for the retaining walls and other vertical surfaces.

The project at a glance
Object: National Capital Region Transport Corporation (NCRTC) Quarters, Ashram
Location: Ashram, New Delhi, India
Scope: basement waterproofing
Raft (horizontal substrate): ULTRABASE PA (sand finish)
Retaining walls (vertical substrate): ULTRAFLEX SA HDPE
Area: 12,000 m²

Why basements need more than a coating
Below-ground structures are in constant contact with soil moisture and groundwater. In Delhi, the monsoon adds heavy rain and a rising water table. Water that finds a way into a basement can damp the walls, corrode reinforcement and damage everything inside, and it is expensive to cure once the building is in use.
In residential buildings, where people live above the basement for decades, waterproofing is a long-term promise made at the construction stage.

ULTRABASE PA (sand finish)
For the horizontal raft, TECHNONICOL used ULTRABASE PA (sand finish), a pre-applied HDPE membrane. It is a composite sheet of thick HDPE membrane with a special pressure-sensitive adhesive compound, protected with sand. The membrane is laid first and the concrete is poured on top of it. The adhesive reacts with the wet mortar and forms an integral bond, so the membrane bonds directly to the concrete, sealing it and preventing water ingress around the structure, even in cases of soil sedimentation.

Key advantages:
- Complete adhesion to the concrete, thanks to the reactive adhesive combined with sand
- High dimensional stability and resistance to puncture and tear
- Trafficable while reinforcement is fixed and concrete is poured
- Barrier to water, moisture and gas, suitable for different soil conditions
- Weather and UV resistance, and strong resistance to industrial chemicals

ULTRAFLEX SA HDPE
For the retaining walls and other vertical surfaces, TECHNONICOL used ULTRAFLEX SA HDPE, a self-adhesive, carrier-less SBS-modified bitumen membrane. A special self-adhesive polymer-bitumen binder is placed on a cross-laminated HDPE film that covers the material on top, and the bottom is protected by an easily removable film. It is designed for waterproofing foundations and the blind sides of below-grade walls.

Key advantages:
- Cross-laminated HDPE film gives additional dimensional stability
- Outstanding elongation helps prevent damage from movements of the substrate
- Self-adhesive lateral overlap strip on the top surface for reliable joint sealing
- Applied without gas or flame, which is safer and quicker, with no additional equipment or special skills
- High repairability

Planning a basement or foundation?
Whether it is a residential complex, a hospital or a transport hub, a dry basement starts with the right waterproofing system. Explore our foundation solutions or contact the TECHNONICOL India team.

Share the article