Mastic asphalt roofing 150 years on is still the most versatile waterproofing used in the construction industry. This hot molten hand laid seamless material still continues to provide unbeatable protection from water ingress always developing and evolving. Mastic asphalt has been reformulated over the last 40 years to include advanced polymers giving elasticity to this already durable material. Mastic can be laid on most types of structural decks such as pre-cast concrete, timber deck and metal decking.
Thermal insulation materials can easily be installed as part of a mastic asphalt specification, also giving the required values. If insulation was required in a roof specification a vapour control layer would need to be installed.
Mastic asphalt can be applied to form a continuous waterproof cover to all types of substrates from flat curved and can be hand formed around rooflights, circular pipes and will bond to a variant of material and projections.
The beauty of the product is that it can be hand laid to all rigid substrates from concrete, timber, deck units, metal decking and many other materials. With mastic asphalt it can also be applied to thermal insulation and achieve any required u-value. Finished treatments means that with added aggregates and solar properties of highly foot trafficked surfaces can also be achieved and create a decorative finish that is very pleasing to the eye.
Within the roof surface condensation is always present and vapour control measures can be achieved within the roof build up system beneath the insulation, this creates a ‘warm roof’ and all types of systems must be laid strictly in accordance with manufactures instructions, from cork, cellular glass, perlite, polyisocyanurate foams and extruded polystyrene.
Before the asphalt is applied to the insulation surface a separating membrane must be laid to the surfaces this can vary from surfaces and specifications, sheathing felt, staple tissue and building paper. It must also allow a free lateral passage for hot air and moisture vapour during the application of hot asphalt and act as a long-term vapour pressure release layer. The membrane is laid with joints of 50mm and is ‘loose laid’ to all horizontal surfaces. Within the grades of asphalt there are special grades in its roof star range and are not limited to black in colour and export grades can be achieved for roofing.
Permaphalt is a formulation polymer modified and is flexible at low temperatures. All application should be in accordance with B58218 and B5800: Part 4.
Sloped surfaces up to 10°will be laid on sheathing felt with a total thickness of 20mm in 2no passes, all finishes will need to be solar painted to minimise heat build up through solar radiation.
On the application to upstand junction (vertical) surface keying must be applied with high bond primer and on bricks/ stonework tucked into a chase line 25mmx 25mm. the upstands will be applied with a trowel on the 1st pass and float applied with the topcoats, formed with no outstanding laps. Surfaces must be clean and dry for bonding to vertical substrates. They key to vertical or sloping timber expanded lathing over black sheathing felt shall be fixed with 25/20mm nails or galvanised staples with 150mm centres. The height of the upstand junctions should be 150mm in height and the total thickness 13mm-20mm, should the asphalt upstand be applied to a freestanding kerb a separating flashing (cover flashing) shall be fitted with the protection of solar paint.
Special Rwo details with need to be fitted and clamping rings to cast iron or aluminium silicon alloy Rwo with a bellmott opening used as well as (code45) lead shoots fitted and the asphalt formed into and around details.
Once the field area is complete along with the upstand junction (vertical) a double fillet seal if fitted, this is applied in 2no passes, (warmed cleaned) this seals the horizontal to the vertical. On the roof edges GRP trims can be fitted as well as lead aprons with a bullnose finish to seal roof edges and to pervert a capillary at the above detail.
Once all items have been applied all surfaces will require a solar a solar reflective coating as a finish in 2no coats, there are a variant of colours which will leave a pleasing finish.
“I found Heritage Asphalt by accident on the Internet. It was a video about asphalting steps. I called Ryun who was very professional and had a great deal of experience and knowledge. The job was booked in straightaway and a team set about taking off old asphalt rebuilding and repairing the big Victorian staircase and then asphalting. The finish was quite amazing, these guys are very skillful at what they do and My husband and I were delighted. They were a professional team really hard working and highly recommend them.” Customer in London
“First class job - very polite. Couldn't have chosen better - highly recommend this company. Thank you.” Mrs Susan Knight
“Perfect service. Will happy use them again if required to.” Trevor Trim
“This company goes 'the extra mile' in both workmanship, customer satisfaction and consideration.” Mrs A Lighterness
“Ryan and team arrived, late afternoon, as agreed, to review balcony, approx. 25m2, 3 sides fed by tiled roof and one long length hand-rail. Problem, 3 leaks in different places from 10yr old asphalt roof. We discussed the problem and Ryun suggested a choice of two plan of action. We found his quotation very acceptable. This work was completed as agreed, in only a few days, to our complete satisfaction. Eight months after completion, I can now report that after a very wet winter, the roof is in a sound state. An excellent job done.” Customer in Cambridge