Retroflect: Technical Data

Info Techncal Data Health and Safety Info

BS 5750

All three WH Screeton solar reflective coatings are manufactured to BS 5750: Part II Quality Assurance to ensure that the products are of the highest standard and maintain the company's market leading position.

Durability

WH Screeton products have been developed to meet the most rigorous rooftop conditions. Neither emulsion nor aluminium-based coatings will withstand saturated moisture conditions, water ponding, freezing temperatures and the equatorial sun, all in quick succession. They can, without detriment, be applied to very hot surfaces and will withstand water puddles at night followed by rapid drying out, repeatedly. Because of the pigmentation, the chemicals are chemically stable and with a high resistance to industrial pollution and provide protection from the effects of acid rain.

Preparation

The roof surface should be completely clean before application. If necessary, use Fungicidal concentrate diluted by 200 parts clean water to 1 part concentrate as part of the preparation. When dry, remove all dead matter from the surface. Where roofs have been treated with materials other than Retroflect, please contact the Technical Advisory Services.

Asbestos cement roofs should be treated as above. Where lichen growth is established, controlled water lancing offers the best solution.

Metal decking should be cleaned as above and inspected for rusting and oxidation. Clean to a sound surface and apply metal primer to affected areas before treatment.

Coverage

On smooth asphalt or bituminous felt, Retroflect should achieve 6 square metres per kilo per coat. On well weathered or mineralised bituminous roofing felt the coverage per kilo will be reduced.

Application

WH Screeton products are ready for use, one pack products for application with a conventional 23cm wide roller. Two coats should suffice and up to 24 hours drying time should be left between coats. Depending climatic conditions at the time, overnight accumulation of moisture must be dried off prior to the second coat which should be applied at right angles to the first.

To keep rollers soft between coats, wrap tightly in a polythene bag. Equipment should be cleaned with Retroflect Roller Cleaner.

Airless spray application can be used on large areas and corrugated sheeting. In these instances contact the Technical Advisory Service prior to application. Airless spray should only be used by experienced operators.

Maintenance

Coatings should be reapplied approximately every five years. The roof area should be cleaned and two coats applied. Should repairs be necessary, thoroughly wire brush the overlap area before starting repair work. Regular inspection is recommended to ensure the efficiency of the roof structure is maintained.

Caution

• Consult the Technical Advisory Service when high polymer felts are to be coated.
• Surfaces must always be correctly prepared before application.
• When using airless sprays, adjacent vertical and horizontal surfaces must be protected from overspray.
• Airless spray units operate using high air and liquid pressures. Never open, break, adjust or clean the unit when it is under pressure.
• Airless spray should only be used by experienced operators
• DO NOT use in the presence of naked flame.

Advantages

• A purpose made solar reflective coating for asphalt, bituminous membrane, asbestos and metal deck roofing.
• Reduces the absorption of solar energy and resultant movement.
• Reduction of infra red and ultra violet degradations of asphalt and bituminous membranes.
• Less weight to be lifted to roof level.
• The elimination of damage caused by secondary trades walking on the chipped surface.
• Repaired areas can be easily and economically recoated to restore heat reflection.
• High retention of solar reflective quality over prolonged periods of time.
• Application / equipment simplified and low cost.
• Outstanding durability proven over the past 20 years.
• Ringbolts, lightning conductor-strip, flashings and cappings may be coated to reduce heat gain and transmission of heat to adjoining surfaces.
• Durability unaffected by ponding of rainwater.

Additional Benefits for Flat Roofs

• Much lower transports costs than for chippings.
• Elimination of blocked drains. No risk of blowing off high-rise buildings as can happen with small chippings.
• Damaged roof areas more easily treated. No moving of chippings to find leaks and therefore no risk of localised weight loading.
• Large reduction in overall weight loading of roof, e.g. RetroFlect dry film weight approximately 90 grams per sq metre. Chippings approximately 4.5 kilos per sq metre.

Problems

Traditional roofing treatments include aluminium and emulsion-based products, paving slabs and chippings. All of these introduce their own problems.

Aluminum-based products have proved to be chemically unstable when exposed to the elements - they rapidly deteriorate with industrial contamination and water bound alkali. Therefore, aluminium coatings suffer from rapid fall off of relative reflectivity as they tarnish. Furthermore, some solvents used in the manufacture of aluminium coatings are detrimental to bituminous surfaces.

Emulsion-based products are subject to rapid breakdown when water accumulates on the surface. There are also unsuitable for application on hot and warm surfaces as the evaparation of the water phase can interfere with the film formation.

Causes

Flat roofs deteriorate for several reasons including stresses caused by temperature fluctuations, ultra violet attack and environmental pollution. Stress is placed on the roof by a wide and frequently changing temperature range. Solar heat absorption leads to heat build-up within the membrane and supporting structure. The subsequent thermal movement can be extremely damaging, particularly in new buildings where modern construction methods and increased thermal insulation leave little latitude for thermal movement.

Deterioration is also caused by industrial contamination and environmental pollution. These can lead to physical and chemical attack, lichen growth and, in some cases, softening and splitting. Ultra violet radiation and nightime heat loss also reduce the efficency of the roof.

Solutions

Retroflect is a unique solar reflective coating containing a titanium dioxide pigment base - one of the highest quality inorganic reflective products currently available. Available in white, green and grey finishes, coatings dramatically improve the efficiency and lifespan of flat and pitched roofs.

The inorganic Retroflect pigments offer superior reflective qualities and are suitable for use on asphalt, bitumen, torch-on, single ply, metal decking and asbestos cement roofing systems. Relative solar reflectivity readings for the coatings are: Retroflect White 85%, Retroflect Green 75% and Retroflect Grey 65%.

Unlike alternative coatings, WH Screeton products use only chemically stable pigments and so remain effective in even the most demanding climatic, environmental and industrial applications. First launched some 20 years ago, the coatings have been used in the UK, the Middle and Far East, America and Australia where they have reduced roof level temperatures by 50% or more and the subsequent thermal movement correspondingly.

As a direct result of this reduction in temperature, solar reflective coatings provide what is called passive air conditioning by cutting down thermal transmission, thereby reducing internal energy and consumption costs.

Reduced Energy Consumption

As the emphasis on environmental problems increase, so the need to reduce energy consumption grows. Solar reflective coatings directly reduce energy consumption costs and in particular those relating to air conditioning.

The equation is simple: the warmer the roof, the greater the load on the air conditioning plant and the more costly it becomes in terms of operation and maintenance. A solar reflective coating will reduce the roof temperature and so minimise air conditioning costs. The table below shows the exact degree of solar reflectivity achieved by the three WH Screeton products: Retroflect White, Retroflect Green and Retroflect Grey. These measurements were taken across the entire solar spectrum.

Retroflect White:	85% solar reflective.
Retroflect Green:	75% solar reflective.
Retroflect Grey:	65% solar reflective.

 

Passive Air Conditioning

Retroflect's passive air conditioning qualities are highlighted on an American test roof in California. Following the application of Retroflect, the roof temperature was reduced from 58°C to 27°C and energy consumption costs subsequently more than halved.

Retroflect also has significant price benefits on flat roofs over traditional paving slab and chipping alternatives in terms of cost per square metre and weight loading.