There are many types of liquid applied membranes and the majority of them are covered by European Technical Approval Guideline 005 Liquid Applied Roof Waterproofing Kits. This provides an ideal basis for a system to describe the different type of liquid applied membranes. There are some, however, that are not covered by the ETAG, but this should not detract from their use as long as they have a valid BBA Certificate for their intended use. Further information on these generic types can be found in Guidance Note No. 3 Generic Types of Liquid Applied Waterproofing Systems for Roofs, Balconies and Walkways and suitable applications are shown in the Product Selector.
It is recommended that only systems holding current third-party accreditation such as agrement (such as BBA or BDA) or ETA certificates should be specified.
ETAG: PART 2
Polymer Modified Bitumen Emulsions and Solutions
In these systems bitumen is modified with suitable polymers or co-polymers in order to enhance durability, flexibility and elasticity to the dried coating. These products can be supplied as water based emulsions or solvent based solutions. Water based products are normally applied in appropriate weather conditions as recommended by the manufacturer.
In addition to bitumen and polymer modifiers, both the emulsion and solutions may also contain inert fibres and fillers. The products are designed for application by brushing or spraying or may be suitable for spreading. The systems may also require primers, reinforcements and solar reflective or protective finishes.
ETAG: PART 3
Glass Reinforced Resilient Unsaturated Polyester Resins
These systems are often referred to as GRP, glass fibre or fibreglass. They consist of a glass fibre reinforced polyester resin cold applied on site.
The unsaturated polyester resins used need to be specifically formulated for roofing or balcony purposes to provide a combination of wear-resistance, flexibility, elasticity and fire performance. Pre-formed components usually referred to as GRP trims can be used to provide a fast, reliable and neat solution to finishing details.
ETAG: PART 4
Flexible Unsaturated Polyester Resins
These systems consist of an unsaturated polyester resin reinforced with a polyester fleece. They can be sprayed or hand-roller applied. It is recommended that only systems using unsaturated polyester resins specifically formulated for roofing or balcony purposes should be specified.
The unsaturated polyester resins incorporated within the system must be specially formulated for roofing purposes to provide a high degree of flexibility and elasticity combined with fire performance.
ETAG: PART 5
Hot Applied Polymer Modified Bitumen
More generally referred to as Hot Melts, these products are based on hot applied polymer modified bitumen which is usually applied in two layers incorporating a polyester reinforcement. Due to the relative softness and tacky surface of the material a surface protection membrane is applied to the topcoat. The protection membrane varies dependent upon roof usage and access required.
The system can only be used as an inverted/buried roof membrane application or in roof garden/green roof design and therefore can only be used on roofs of up to 15 degrees pitch. The material is sensitive to UV light and at all upstands/details where the membrane becomes exposed a protective membrane must be applied to prevent UV degradation.
ETAG: PART 6
Polyurethanes
Polyurethanes may be single or two component, aliphatic or aromatic and cure/dry by reaction, or moisture trigger from latent hardeners, or by moisture cure from the air – possibly some of these in combination. They are formulated to give good fire performance and are highly resistant to UV light with aliphatic based product having better colour fastness. Whilst single component polyurethanes usually contain solvents, two component systems can be formulated solvent free.
Reinforcement is used either locally or overall to produce tough, long-lasting systems; although unreinforced polyurethane is a very tough material in its own right and reinforcement may be added selectively.
Polyurea Systems
Polyurea Liquid Applied Waterproofing Systems (LAWS) are chemically similar to polyurethanes but have key chemical differences that can result in quite different application characteristics and physical properties. Due to the typically high tensile strength and elongation of polyurea LAWS, they are usually applied in one coat. Fabric reinforcement is not usually required.
Polyurea LAWS are typically very fast cure, durable, damage resistant and have good long-term resistance to UV light and infra-red radiation.
ETAG: PART 7
Bitumen Emulsions and Solutions
In these systems either blown (oxidized) or unblown bitumen is supplied as water based emulsions or solvent based solutions. In both cases these products do not have added polymer modification. Water based products are normally applied in appropriate weather conditions as recommended by the manufacturer.
In addition to bitumen, both the emulsion and solutions may also contain inert fibres and fillers. The products are designed for application by brushing or spraying. The systems may also require primers, reinforcements and solar reflective or protective finishes.
ETAG: PART 8
Water Dispersible Polymers
These products form a generic family which covers a wide range of emulsion or dispersion coatings, the common characteristic is a water based binder plus additives which dry via the coalescing process as water evaporates.
They can be applied by airless spray, air-assisted spraying, roller or brush. The systems may also require primers, reinforcements and solar reflective or protective finishes. Water based products are normally applied in appropriate weather conditions as recommended by the manufacturer but are highly waterproof once dry.
Additional systems
A range of resins for Liquid Applied Waterproofing Systems has evolved over the years, which are not covered by the existing ETAG (parts 2-8):
Methacrylates
Sometimes described as Acrylics, MMA or PMMA, these products are formulated to achieve the required physical performance by using various polymers dissolved in reactive methacrylate and acrylate monomers. These two-component, solvent-free products are generally applied by spray, although they can be formulated for roller, brush, trowel or squeegee applications.
They cure by an extremely rapid in-situ polymerisation, which is activated by the addition of a peroxide catalyst. This curing proceeds rapidly even at temperatures around 0°C. All methacrylate coats chemically react with each other to produce a fully-bonded composite.
The systems incorporate primers to ensure adhesion on a variety of substrates and reinforcement can be incorporated if required. The use of Bond Coats can allow them to be overlaid with asphaltic surfacing. On exposure to UV light, they display very good retention of physical properties.
Although not specifically covered by the ETAG, some manufacturers have tested their roofing products against Part 4.
Acrylic Roof Coating Systems (Solvent Based)
A one component polymeric composition for use in repairing and coating leaking roofs, gutters and similar structures. They are particularly useful in an emergency repair situation in adverse weather conditions and will cure under water.
Applied by roller or brush direct onto a clean, dust-free surface with any wide gaps being reinforced with glass-fibre tape. Most sound surfaces are suitable without a priming coat but priming is required on fresh bitumen, metal or asbestos.
Thermoplastic Block Copolymers (S-EB-S),(S-EP-S)(Solvent Based)
These are flexible single component systems which are applied to produce multilayer coatings. They can be spray, roller or brush applied. Internal reinforcement layers can be incorporated to increase the lifetime of the coating. Most sound surfaces are suitable without a priming coat but priming is required on fresh bitumen, metal or asbestos.