Sikalastic Rapid-721

Manufacturer: Sika 

Materials: Poly Methyl Methacrylates (PMMA) 

Sikalastic Rapid-721 comprises the following components:
• Sikalastic Rapid-721 — a two-component polymethyl methacrylate waterproofing resin available in dark grey (RAL 7043)
• Sikalastic Rapid-721 Thixo — a thixotropic version of the standard resin, for use in detailing at upstands, corners, connections and other details, available in dark grey (RAL 7043)
• Sikalastic Rapid Fleece 110 — a 1.10 kg·m–2 polyester fleece for use as a reinforcement
• Sikalastic Rapid Asphalt Primer — a non-pigmented primer based on a two-component fast-reactive polymethyl methacrylate resin, for the preparation of asphaltic and bituminous substrates
• Sikalastic Rapid Cementitious Primer — a non-pigmented primer based on a two-component fast-reactive and fastcuring polymethyl methacrylate resin, for the preparation of absorbent substrates such as concrete, screeds and timber.

BBA logo

Number: 20/5848
Issue date: 12/02/2021

Approved for use on

Flat Roofs Green Roofs Pitched Roofs Roof Gardens Zero Falls Buried Roofs 

The system is also satisfactory for use in green roofs on flat, zero fall and pitched roofs and roof gardens on flat, zero fall on concrete substrates. The adhesion to, and compatibility with, other substrates must be confirmed by test


Concrete Metal Plastic Reinforced Bituminous Membranes Timber 

Sikalastic Rapid-721 is satisfactory for use as a waterproofing system on flat and pitched roofs with limited access,
on substrates of:
• concrete
• bituminous
• timber
• metal
• plastic.


25 Years 

Sikalastic Rapid-721 will achieve a service life in excess of 25 years

Installation Requirements

The system should only be installed by installers who have been trained and approved by the Certificate holder.

Fire Safety

When tested to BS 476-3 : 2004 a system comprising a 12 mm thick gypsum glassrock roof board, primed with Sikalastic Rapid Cementitious Primer and coated with Sikalastic Rapid-721 reinforced with Sikalastic Rapid Fleece 110, achieved a EXT.F.AC rating and will be unrestricted by the national Building Regulations.

In the opinion of the BBA, a roof incorporating the system will be unrestricted under the national Building Regulations in the following circumstances:
• Protected or inverted roof specifications, including an inorganic covering listed in the Annex of Commission Decision 2000/553/EC,
• a roof garden covered with a drainage layer of gravel 100 mm thick and a soil layer 300 mm thick,
• irrigated roof gardens and green roofs.

The designation of other specifications should be confirmed by reference to the requirements of the documents supporting the national Building Regulations.

The system, when used in pitches of greater than 70°, excluding upstands, should not be used on buildings in England and Wales that have a storey at least 18 m above ground level and which contain: one or more dwellings, an institution, a room for residential purposes (excluding any room in a hostel, hotel or boarding house), student accommodation, care homes, sheltered housing, hospitals or dormitories in boarding schools.

The system, when used in pitches of greater than 70°, excluding upstands, should not be used on buildings in Scotland that have a storey at least 11 m above ground level.

If allowed to dry, plants used may allow the spread of flame across the roof. This must be taken into consideration when selecting suitable plants for the roof. Appropriate planting, irrigation and/or protection must be applied to ensure the overall fire-rating of the roof is not compromised.

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Sika House
Miller Street

T : 01772 259781

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