Liquid Membranes

Hasan Rizvi
The concept of liquid waterproofing has existed since the early 1800s, when natural bitumen was combined with jute, straw, rag felt and other man made materials to provide a waterproofing solution. There are other different kinds of waterproofing system, which can be categorized as following
  1. Pre formed Membranes like TarFelt, Plastic Felt, APP Membrane, PVC etc.
  2. Integral Waterproofing Compound like ShaliPlast LW, LW+
  3. Liquid Applied Membrane (LAM) like Acrylics, Polyurethanes, Bituminous emulsion etc.
Waterproofing with pre-formed membrane is being used since ages and have joints, can not be applied in difficult geometrical structures, requires technical applicators and is not a fully bonded system. Repairs are costly

As the name suggests, Liquid waterproofing membrane comes in liquid form and after application it dries to form a seamless, smooth and continuous barrier to water. Technologically it's an advanced system, with guaranteed performance. Liquid Applied Waterproofing Membrane Systems (LAM's) are protective coatings and are either of one or two component, usually Acrylic, Polyurethane, Bituminous base, or a hybrid combination.

LAM can be used for new projects or refurbishments, Liquid Waterproofing Membrane Systems can be used in all areas of roofing, planters, sunken areas, landscapes, pedestrian areas, car parks and structural waterproofing. LAM's are preferred products for corrugated roofing sheets and especially in projects where heating is not allowed like Refineries etc.

Waterproofing with liquid membranes is gaining popularity and have considerable benefits over traditionally used pre-formed membrane systems:–
  • Ease of application / User friendly
  • It is a fully bonded system, thus ensures greater security against infiltration or damages to liquid membrane
  • Monolithic system i.e. without joints.
  • They can be installed easily on any contour surface.
  • Easily Repairable
  • Environment Friendly
  • Exhibits good waterproofing and elasticity
  • Weather / Ageing
Installed cold and hence does not require heating. Very simple to apply by brush / roller. Semi skilled professionals can do an excellent job. Moisture cured polyurethane liquid membranes can be applied in moist roof like ShaliUrethane BTD. These products help enable projects to be carried out with minimum disruptions throughout the year. Ease and speed of Installations significantly reduces the cost of waterproofing thus making it cost effective.

Roof Waterproofing

LAM is a fully bonded system which means that when the LAM is applied in Liquid form it bonds with the surface and then the curing takes place. The cured membrane almost becomes the integral part of the structure. The advantage it gives is that if the membrane gets damaged at one small point, it will not affect the rest of the structure, whereas in pre-formed membrane system water can travel through the damaged portion and can affect other parts of the structure.

System is Monolithic and can be applied in one piece (unlike conventional membranes that are rolled out in sheets) to various roof shapes which means no risk of water entering between the seams and are very easy to apply especially when faced with various obstacles. LAM have high crack bridging property, one can easily seal any cracks with products like ShaliUrethane LHM, ShaliUrethane FG, ShaliCryl LM.

Liquid Membranes

Since LAM is applied in the Liquid form it can take any shape or contour.

LAM is repairable and quick patch job can be done easily. Compatible with most substrates, it is also easy to re-coat, old coatings or can even be laid on damaged membrane systems. These systems can be laid at little surface preparation costs. On the contrary, damaged pre-formed membranes requires complete removal, cleaning of the substrate and then complete new installation.

Waterproofing of Overhead Tak

In the range of LAM there are Water based products some of which are GREEN. These products are made out of Cleaner technology & are non-toxic.

The exterior of the membranes can have various aesthetic finishes so that it can suit the ambience. Available in pleasant colours, ShaliCryl 215 is a unique elastomeric high build coating based on a revolutionary acrylic polymer with quick-set capabilities to resist premature moisture attack. ShaliCryl 215 provides durability, flexibility, and excellent weather resistance. Because of a unique UV cross-link curing mechanism it becomes more durable with age. It is easy to apply and is environmentally safe and non-polluting. ShaliCryl 215 has inherent waterproofing qualities.

LAM has excellent adhesion with the substrate and being a fully bonded system it acts as a barrier coat against water ingress. LAM have elongation range of 100% to over 500% which makes it very durable and helps it to accommodate structural movements. ShaliUrethane LM and LHM has significantly higher elongation.

Two-Components Cementitious elastomeric Liquid applied Waterproofing membrane: ShaliCem EWP of STP Ltd can be reinforced with glass fibers and is used for waterproofing Roof, sunken, watertank, swimming pools, foundations, retaining walls etc.

- Liquid Applied TarFelt LM Material: This category of product are also very versatile because they allow you to repair old Tarfelt waterproofing solutions without dismantling the existing system, can be used on asbestos roofing, metal sheets, concrete and wood. This can be further coated with liquid applied waterproof paint ShaliCryl215 single component UV Resistant Elastomeric coating.

If protected, it does not crack on aging unlike many preformed membranes. Some of the LAM's are UV resistant and can be exposed to the ambient weather conditions and it prevents Algae and Fungal growth. The temperature gradient is quite wide for these products.

Apart from other brands, STP Ltd is one of the Pioneer company for waterproofing which was established well back in 1935. Trusted for generations, STP has the largest range of new generation and traditional waterproofing products in India.

NBMCW April 2014