TORCH-ON BITUMEN

TORCH-ON BITUMEN MEMBRANE WATERPROOFING

Thermoflex has been in production since 1982 and has been developed specifically for South African conditions, which on the highveld are extreme. Assistance in product evaluation has been provided by the C.S.I.R.

Thermoflex consists of a 180 gram heat set chemically bonded (double reinforced) needle punched polyester geo fabric, manufactured in an ISO 9000 certified plant. This comprises the“ Carrier “ or core of the product. Impregnated into this is S.A.B.S. certified bitumen, which is modified with A.P.P. (attactic polypropylene) and various other components, which provide flexibility and ultra violet light resistance. The weathering surface is treated with an inert silica, which provides a key for adhesion of topcoats, should aesthetics require. The under surface comprises a heat sensitive polymer film which melts at the correct temperature during application.

Over three million square meters of THERMOFLEX has been specified and is successfully performing on roofs throughout Africa. The product is fully backed by our manufacturers guarantee and has a life expectancy of in excess of twenty years.

Full literature and reference to projects are provided in this brochure 

 

Waterproofing system

Product Background

Bitumen remains the most important base material for waterproofing today, this despite the fact that dozens of “miracle” new products have come on to the market. Bitumen is inexpensive, inherently waterproof, durable, has excellent adhesive properties and is non toxic. Examples of five thousand year old applications of bitumen exist in the middle east. No other system has this track record as a waterproofing agent. Unmodified bitumen has the disadvantage of being brittle at low temperatures and soft or liquid at high temperatures. Flexibility  and flow resistance over a temperature range of  zero to ninety five degree centigrade is a prerequisite for South African conditions.
In depth research and development over a nine year period has led to the development of THERMOFLEX A P. ( Atactic polypropylene ) modified torch-on membrane. Specifically developed for harsh African conditions THERMOFLEX A P offers the following.
Vastly improved elasticity capable of accommodating thermal movements of roofs. ( Particularly required with the increase in the use of thermally insulated roof decks. )
Improved flexibility at low temperatures, enabling laying in cold weather.
Improved strength, allowing a single ply application.
Improved resistance at application temperatures, to permanent deformation, puncture and tear. Giving good “walk on” properties during and after application.
Greater capacity to bridge movements of cracks and joints in the substrate and better fatigue resistance.

Why use a ready made Torch-On Membrane ?

Liquid applied waterproofing systems will always find applications. They do however have inherent disadvantages. Due to unevenness in substrates it is virtually impossible for the contractor to apply the product uniformly. Some areas will have product in excess of and others less than specification. Invariably those areas under applied will be weak and problems may occur.
Unscrupulous contractors may deliberately under apply product without necessarily changing the finished appearance of the roof.
A ready made membrane eliminates these pitfalls. THERMOFLEX  A P is a mechanically produced product of uniform thickness. 

 

Properties

Physical PropertiesColour

Black

 Total Solids100%

 Specific Gravity1.3 – 1.4

 Water Vapor PermeabilityImpermeable

 Chemical Resistance

Resistant to mild acids
and alkali solutions.
Not resistant to hydro-carbon solvents, diesel

 Slump Resistance

Will not slump on a                    
vertical surface at 95 c

 Penetration(100g/5s/70c)50-60

 Cold Flexibility(20mm mandrel)  < 5c°

 Elongation @ 25c>25%

 Tensile Strength>900 N/5cm

 Tear Resistance>300 N

ApplicationsConcrete Roof DecksSee application sheet 1

 Planters and Flower BoxesSee application sheet 2

 Under Screed or TilesSee application sheet 3

 Water Retaining StructuresSee application sheet 4

 Vehicular Traffic AreasSee application sheet 5

Description

Thermoflex AP is a torch on APP modified bitumen Membrane, available in 3.5, 4.5, and 6 kg/m sq grades in 10m roll lengths 1m wide

 

 

Construction

The membrane  consists of a 10 micron LDPE plastic to prevent blocking the adhesive layer of modified bitumen a stabilized 180 gm  needle punch polyester carrier

A weathering layer of modified bitumen coated with silica to prevent blocking and supply a surface key for decorative finishing coatings.

 

WATERPROOFING OF CONCRETE ROOF DECKS

Discussion

Concrete roof decks normally consist of a slab screeded to a fall with a sand cement mixture. In the case of a new structure, a minimum of 2 rain free weeks drying period is required before waterproofing. In the case of an old roof, existing waterproofing should be removed and a drying period consistent with the amount of water absorbed allowed. As this is often difficult to estimate it is suggested that either our technical department is consulted or vent pipes ( 10 sq. m of roof area ) are provided to  prevent bubbling due to trapped water vapour.

Surface Preparation

All forms of surface contamination must be removed to ensure a clean smooth surface free of any loose material, or any other barrier to adhesion. Cracks or voids must be filled using HYPERCRETE  (modified cementitious material ) and allowed to cure for a least 24 hours. Should the parapets be rough a HYPERCRETE slurry should be applied to the area to receive the flashing. Fullbore covers should be removed to facilitate “dressing in” the waterproofing. It is recommended that the fullbores be checked to ensure they are functioning correctly.
Finally, an assessment should be made, as to what extent if any ponding is likely to occur. Standing water present, in excess of 5 mm is considered excessive. All low areas should be levelled with a topping of HYPERCRETE. Waterproofing over expansion joints should be laid on top of a PVC slip-sheet once the joint has been sealed. Under no circumstances should the waterproofing be laid directly over the expansion joint.

Application

 Apply a thin uniform coating of THERMOFLEX PRIMER by means of a paint roller to the entire area including the parapets. Coverage will depend on the porosity of the substrate, but 6 sqm/ L of primer should be obtained. Allow a drying period of 3 hours. Lay up the entire roof area allowing 75 mm overlap on side joints 100 mm on end joints and at least 200 mm for turn-ups at the parapets. Joints can now be torched together and all edges sealed with a heated trowel.

Flashings

It is recommended that the THERMOFLEX be turned up the parapets 150mm. A DARAFLEX flashing strip of 300mm should overlap the turn-up in such a manner that 100mm of its width be on the horizontal plane and 200mm on the vertical. (See DARAFLEX data sheet)

Finish coat   

A choice of REFLECT (Bitumenous Aluminium Paint) which is highly reflective or DARACRYL Acrylic (available in colours ) must be applied. If the acrylic topcoat is chosen, a pastel shade is recommended to improve reflection and reduce surface temperature.

Application        

Before applying REFLECT ensure that the product has been well stirred. The product should be applied with a paint roller at an application rate of 5 sqm/L. NOTE: The paint should be stirred at regular intervals to ensure a consistent appearance. The coating must not be applied under wet conditions or to a moist surface. REFLECT is a solvent based material, is highly flammable and should only be applied in a well ventilated area.
When applying DARACRYL to a very hot THERMOFLEX surface a mixture of one third paint to two thirds water should first be applied as a primer coat. Allow 30 minutes drying time before applying DARACRYL with a paint roller, at an application rate of 3sqm/L. DARACRYL only develops full water resistance after a few days. It is therefore essential that it is not exposed to excessive ponding during this period. 

Maintenance    

This system is recommended for occasional light foot traffic. The products life expectancy can be significantly improved by re-coating the roof every 2-3 years.

 

 

MORE APPLICATIONS:

 

• WATERPROOFING OF PLANTERS AND FLOWER BOXES

• WATERPROOFING UNDER SCREED OR TILES

• WATERPROOFING OF VEHICULAR TRAFFICABLE AREAS

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