RIW Cementseal

RIW Cementseal 15kg Two-Part Cementitious Waterproofing Coating

RIW Cementseal 15kg is a two-component, polymer-modified, cement-based waterproof coating designed for concrete and masonry. It forms a seamless, fully bonded waterproof barrier and can be applied to damp surfaces, making it suitable for demanding below-ground and structural waterproofing applications.

Cementseal provides resistance to both positive and negative water pressure, with the manufacturer's literature stating resistance to up to 100m head of water pressure. It can be applied by brush or spray and is suitable for basements, sub-structures, plant room floors and temporary waterproofing.

Key Benefits

• Two-component polymer-modified cementitious waterproof coating
• Totally waterproof
• Resists up to 100m head of positive and negative water pressure
• Seamless and fully bonded
• Can be applied to damp surfaces
• Resistant to abrasion and impact
• Suitable for brush or spray application
• Enhanced resistance to carbonation
• Suitable for below-ground waterproofing
• Can be used for temporary waterproofing
• Suitable for concrete, masonry and steel
• CE marked and assessed to EN 1504-2
• Reaction to fire classification Euroclass A2-s1, d0

Applications

RIW Cementseal is suitable for:

• Basement waterproofing
• Cellar waterproofing
• Below-ground structures
• Sub-structure waterproofing
• Internal tanking
• Concrete waterproofing
• Masonry waterproofing
• Plant room floor coatings
• Temporary waterproofing during construction
• Waterproofing areas exposed to water pressure
• Protection of concrete against water penetration and carbon dioxide diffusion

It can be applied to:

• Concrete
• Masonry
• Steel

Technical Information

Technical information is taken from the RIW Cementseal technical literature. The stated performance figures are typical values and should not be considered a product specification.

Surface Preparation

Surfaces must be clean, sound and free from loose or unsound material, including dust, oil, grease, corrosion by-products and organic growth. Smooth surfaces should be roughened.

The prepared substrate should be thoroughly soaked with clean water until uniformly saturated, but without standing water. Internal corners should be formed with RIW Cementfill HB to create a continuous minimum 25 × 25mm fillet before Cementseal application.

Existing finishes should be completely removed back to the structure. Pressure washing is recommended to help saturate the substrate and remove soil, dust and loose debris. Defective mortar joints should be repaired, while damaged masonry should be repaired using suitable RIW Cementfill products.

For concrete substrates, the concrete sub-base should have a minimum strength of 20N/mm², with surface laitance removed before application.

Mixing

Cementseal is supplied as a pre-measured two-part system. Shake the liquid component thoroughly and pour it into the supplied tub before slowly adding the powder.

Mix for a minimum of 5 minutes using a slow-speed drill and suitable paddle designed to minimise air entrainment. A normal concrete mixer is not suitable.

For smaller applications, part packs can be mixed using an initial ratio of approximately 3.5 volumes of powder to 1 volume of liquid, adjusting as necessary to achieve the required consistency.

Application

The mixed Cementseal slurry can be applied by brush, squeegee or spray to a pre-soaked surface. Care should be taken to avoid trapping air against the substrate.

For horizontal surfaces, Cementseal can be applied as a single 1mm or 2mm layer, using a skid leveller or notched trowel, followed immediately by a spiked roller to release trapped air.

For other surfaces, apply two 1mm coats. The second coat should be applied when the first is stable but not fully set, typically after approximately 30–60 minutes, depending on temperature.

Curing should commence within 10–15 minutes of completing application. Protect the coating from strong sunlight and drying winds during curing.

Ancillary Products

RIW produces a range of products designed for use alongside Cementseal, including:

• RIW Cementseal Primer – for horizontal and porous surfaces and also usable as a curing membrane
• RIW Cementfill FC – waterproof fairing coat and repair mortar
• RIW Cementfill HB – waterproof high-build repair mortar for profiling and forming fillets
• RIW Cementjoint – flexible waterproof composite tape for reinforcing joints

Storage & Shelf Life

Store Cementseal containers in dry, frost-free conditions. The stated shelf life is 12 months in unopened containers at 20°C.

Frequently Asked Questions

What is RIW Cementseal used for?

RIW Cementseal is a cement-based waterproof coating used for basements, cellars, sub-structures, plant room floors and temporary waterproofing applications.

Can Cementseal be applied to damp concrete?

Yes. The manufacturer specifically states that Cementseal can be applied to damp surfaces, provided the substrate is properly prepared and saturated without standing water.

How much area does a 15kg pack cover?

One 15kg pack yields approximately 7.9 litres of slurry and is sufficient to treat approximately 4m² at 2mm thickness.

How thick should Cementseal be applied?

For soffits and vertical surfaces, apply 2mm in two coats. For floors, the specification allows 2mm in one coat. Temporary waterproofing can be applied at 1mm in one coat.

How long should I wait before applying the second coat?

The second coat should generally be applied after approximately 30–60 minutes, when the first coat is stable but not fully set. The actual timing depends on temperature.

Downloads

Data Sheet