What is it?
Mastic asphalt has definitely stood the test of time, being the oldest waterproofing method dating back to the 19th Century. It has been modified over the years and is still used today, boasting a carbon zero rating. The versatility and durability of this material as a waterproofing solution is apparent from the numerous surfaces and applications it can be used for, such as Roofing, Flooring, Tanking, Car Parks and Balconies. Asphalting has always been considered a specialist technique in the construction and building industry, largely due to the training required to utilise it. Here at OptiTec Ltd
Types of Mastic Asphalt
Tanking BS 6925:1988 – Mastic Asphalt is one of the oldest waterproofing tanking methods, it can be used as an internal tanking method or for external tanking. The application of this system creates a seamless and continuous waterproofing lining. Tanking asphalt must always be laid in 3 coats to a total thickness of 20mm for vertical work and 30mm for horizontal work, in accordance with Code of Practices BS8102. Tanking should be laid directly to the dry substrate without a separating membrane. However, a layer of glass fibre tissue with minimum 50mm laps may be needed on horizontal work if excessive blowing is encountered.
- OptiBond Asphalt-TB –100% bitumen binder. An economic tanking asphalt.
- OptiBond Asphalt-TT25 –25% Trinidad Lake asphalt 75% bitumen binder. Improved laying properties and greater thermal stability.
Flooring BS 6925:1988 – Mastic Asphalt flooring can last longer and outperform all other flooring materials on the market, it can be laid over many different structural bases such as concrete, metal flooring and timber boarding, due to its high durability, especially when extra grit is added to the mix, it can withstand heavy foot traffic and is the perfect damp proof material thanks to its amazing natural waterproofing properties. Mastic Asphalt flooring is typically laid in one coat. The thickness depends largely on the anticipated use of the floor. There are 4 basic types of Flooring. The situations below assume a concrete type base. For floors subject to deflection such as timber please contact our Technical team.
- Grade 1 -OptiBond Asphalt-F1 15/20 –Designed for relatively high temperatures (25oC–35oC) Such as hospital wards, schools, offices and shops with heavy movable racking. Laid 15-20mm thick on Glass Fibre Tissue (GFT)
- Grade 2 -OptiBond Asphalt-F2 15/20 –Usually used as an underlay to the final floor finish in homes, shops with fixed racks and light duty factory situations. Laid 15-20mm thick Usually on GFT.
- Grade 3 -OptiBond Asphalt-F3 20/30 –Designed for to act as the finished surface or underlay in medium industrial factories, hospital corridors, heated sports halls. Any area subject to continuous foot traffic, light hand trucks and trolleys. Laid 20-30mm thick Usually on GFT with non-slip sand rubbed finish or natural float finish.
- Grade 4 -OptiBond Asphalt-F4 30/50 –Designed for use in traditional heavy industry and warehouse situations. Laid 30-50mm thick, direct to a clean firm concrete type base. Suitable under fork lift trucks and heavy loads. When laid without a GFT separating membrane it has excellent impact resistance. It usually has a non-slip sand rubbed finish. Grade 4 is designed to have 6mm coarse aggregate (30–40%) incorporated during melting down on site. On larger jobs it is easier to organise a Hot Charge delivery with the aggregate already incorporated.
Flat Roofing BS 6925:1988– Mastic Asphalt can be applied to form a continuous waterproofing covering over flat, sloped or curved surfaces. It can be easily moulded and worked around pipes, roof lights and other protrusions on the roof to provide a completely seam free membrane. Roofing asphalt is typically laid in two 10mm coats to a total thickness of 20mm over Black Sheathing Felt.
- OptiBond Asphalt-RB –100% bitumen binder. An economic roofing asphalt.
- OptiBond Asphalt-RT25 –25% Trinidad Lake asphalt 75% bitumen binder. Recommended over insulation due to its improved thermal properties. Over time it will weather to a desirable lighter shade of grey than the plain B grade.
- OptiBond Asphalt-RPM -Polymer Modified Roofing. BBA Certified. Improved long term durability and temperature stability.
- OptiBond Asphalt-RRD –Recreational Duty grade roofing for use as a walkway, e.g. to a small number of flats. The first coat of normal roofing is laid 10mm thick over the BSF followed by the gritted-up roofing that is now laid to a thickness of 15mm. If point loading is anticipated the surface should be tiles. RD Grade also available in OptiBond Asphalt-RPM.
Car Parks BS 1447:1988 – Mastic asphalt is one of the leading waterproofing materials for car park waterproofing due to its distinguished waterproofing properties and its durability. Tried and tested mastic asphalt meets all the demands of a modern car park, with the ability to withstand heavy traffic and foot traffic and its proven long-life span paired with its straightforward installation makes mastic asphalt an ideal material for car parks. Paving is typically used on roof top car parks as the wearing course. If the car park is required to be fully waterproof such as over a shop or offices, it is laid directly on top of 20mm of roofing grade asphalt.
- OptiBond Asphalt-P (Ungritted) is designed to have 3mm, 6mm or 10mm coarse aggregate (20–45%) incorporated during melting down on site. For footpath use we do a pre-gritted block. On larger jobs it is easier to organise a Hot Charge delivery with the aggregate already incorporated.
- OptiBond Asphalt-PB –100% bitumen binder. An economic paving asphalt.
- OptiBond Asphalt-PT50 –50% Trinidad Lake asphalt 50% bitumen binder. Improved wearing characteristics and greater thermal stability.
- OptiBond Asphalt-PT50H -Harder version of the T50. Designed for heavily stressed areas such as loading bays and bus stops.
Paving and Balconies – A main use of mastic asphalt on a balcony would be to protect the structure of the building from water ingress.
Stairs – Mastic asphalt is extremely versatility; it can withstand high foot traffic making it a great waterproofing membrane for steps. When used on steps it waterproofs and protects the original substate.
Certified Lifespan in excess of 25 years
Available Guarantees of 15, 20 & 25 years
Certified for Green Roof
NHBC Projects Approved
Installed All Year Round
Holds Broof T4 Fire classification
Long Term UV Resistance
Excellent Bonding to most roofing substrates
Respects the environment during production and installation
Allows pedestrian traffic once cured
Technical reports and CAD Drawings