Knowing how to protect torch-on roofing from UV exposure is important for helping exposed waterproofing membranes withstand constant sunlight, heat and changing weather conditions. Torch-on waterproofing membranes are commonly used on flat and low-slope roofs because they provide an effective barrier against water ingress, but when left exposed, the membrane also needs protection from the elements.
In South Africa, this exposure can be particularly demanding. Dark bituminous surfaces absorb a significant amount of solar heat during the day and then cool again overnight. This repeated heating and cooling, combined with prolonged UV exposure, can gradually age the exposed membrane. Over time, this may lead to:
- Increased brittleness
- Surface cracking
- Deterioration around laps and joints
- Damage around roof details
- Reduced long-term performance of the exposed waterproofing system
This is why an exposed torch-on roof should be treated as both a waterproofing system and a protection system.
Waterproofing and UV Protection Do Different Jobs
The torch-on membrane is the waterproofing layer. Its job is to help prevent water from entering the building. A reflective coating performs a different function and can help protect torch-on roofing against prolonged sunlight and UV exposure.
Bitumen Aluminium S1 Reflector is specifically designed for use on exterior bituminous surfaces and torch-on waterproofing membranes. It forms a silver, highly reflective and UV-resistant protective coating over the membrane. The key point is simple:
The torch-on membrane waterproofs the roof.
The aluminium reflector helps protect the waterproofing.
How a Reflective Coating Helps Protect Torch-On Roofing
Black bitumen absorbs heat. An aluminium-pigmented coating creates a reflective silver surface that helps reflect more solar radiation away from the roof instead of allowing the dark membrane to absorb as much heat. This provides two important benefits:
- Helps protect the exposed membrane from prolonged UV exposure
- Helps reduce the amount of solar heat absorbed by the roof surface
The reflective coating therefore creates an additional protective layer between the torch-on membrane and the external environment.
Inspect the Roof Before Coating
Before applying any protective coating, inspect the torch-on membrane carefully. A reflective coating should be applied over a sound waterproofing system. It should not be used to hide existing roof defects. Check for:
- Blisters or raised areas
- Loose or lifting membrane
- Cracks or splits
- Open or failed seams
- Damaged overlaps
- Ponding water
- Defects around roof outlets
- Flashing problems
- Damage around pipes and penetrations
- Problems at parapet walls and upstands
Pay particular attention to places where the roof changes direction, such as where the flat roof surface meets a parapet wall. Outlets, flashings and penetrations are also important because several waterproofing details often meet in these areas. Any waterproofing defects should be repaired before the reflective coating is applied.
Don’t Ignore Ponding Water
Ponding water is particularly important on flat roofs. If water remains on the roof for long periods after rainfall, check the roof falls, drainage system and outlets. A reflective coating cannot correct:
- Incorrect roof falls
- Blocked outlets
- Poor drainage
- Structural depressions
- Other causes of persistent standing water
The roof should be able to drain correctly before the protective coating is applied.
Surface Preparation Is Critical
Good adhesion starts with good preparation. Before applying Bitumen Aluminium S1 Reflector, the roof surface should be:
- Clean
- Dry
- Sound
- Free from loose material
- Free from dirt and contaminants
- Free from fungal and algae growth
Loose or poorly adhered previous coatings should be removed rather than simply covered with another layer. Most importantly, do not apply the coating over a wet roof. Moisture trapped beneath a coating can contribute to poor adhesion, blistering and premature failure.
Treat Fungal and Algae Growth First
If fungal or algae growth is present, treat it before applying the roof coating.
- Apply Fungal Wash generously to affected areas and allow it to soak into the surface.
- After approximately 12 hours, scrub the area thoroughly using plenty of clean water and allow the surface to dry completely.
- If contamination is still visible, repeat the treatment.
- Only continue with the coating system once the surface is clean and dry.
How to Protect Torch-On Roofing with Bitumen Aluminium S1 Reflector
Once the underlying torch-on waterproofing has been inspected, repaired where necessary and properly prepared, Universal Bitumen Aluminium S1 Reflector can be applied. The product should be:
- Stirred thoroughly before use
- Applied by brush or roller
- Applied without thinning
- Applied in two full coats
- Allowed 16–24 hours drying time between coats
Allow sufficient drying time between coats, especially during cooler or more humid weather.
Don’t Apply Too Thinly
Applying enough product is important. The aim is not simply to make the roof look silver. The protective coating needs to form a consistent, continuous layer over the membrane. Very thin application, missed areas or uneven coating may reduce the level of protection achieved. Pay particular attention to:
- Laps
- Seams
- Edges
- Corners
- Upstands
- Areas around penetrations
- Previously repaired sections
These areas should receive even coverage without leaving exposed bitumen.
Maintain a Wet Edge
When applying the coating, work steadily across the roof and maintain a wet edge. In simple terms, try not to stop halfway through a section and return much later to continue. Work from one natural stopping point to another wherever possible. This helps reduce visible lap marks and creates a more even, consistent finish.
Choose the Right Weather Window
Roof coating should always be planned around suitable weather. Drying and curing can be affected by:
- Temperature
- Humidity
- Airflow
- Roof surface temperature
Avoid application if rain, mist, fog or condensation is expected before the coating has had enough time to dry. Cold, damp or humid conditions can slow down drying and curing. Even if the surface feels dry to the touch, the coating may still be curing underneath. Painted surfaces should also not be washed or deliberately wetted for seven days after application.
For this reason, choose a stable, dry weather window before starting the project.
Safety Is Important
Bitumen Aluminium S1 Reflector is a solvent-based product. Keep it away from:
- Open flames
- Sparks
- Smoking
- Other ignition sources
Ensure there is good ventilation when working with the product. Appropriate protective equipment should also be used during application. Working at height presents an additional safety risk, so ladders, access points and working areas should be secure before starting.
What if the Roof Has Been Coated Before?
Older torch-on roofs may already have several layers of maintenance coatings. If the existing coating is loose, flaking or poorly adhered, it should be properly prepared before recoating. Where the previous coating system is unknown, speak to a Universal Paints specialist before applying a new coating system. This helps ensure the new protective coating bonds properly and performs as intended.
Protect Torch-On Roofing with Regular Roof Maintenance
Applying a reflective coating should not be seen as a once-off job that means the roof never needs to be checked again. Periodically inspect the roof for:
- Cracks or splits
- Lifting membrane
- Failed seams
- Blisters
- Ponding water
- Damage around outlets
- Failed flashing
- Problems around parapets
- Deterioration of the reflective coating
Small defects are usually easier to deal with when they are found early. Allowing a damaged seam, crack or penetration to remain untreated can eventually lead to more extensive waterproofing problems.
Protect the Waterproofing That Protects Your Home
Torch-on waterproofing protects the building from water ingress, but when the membrane remains exposed, it is equally important to protect torch-on roofing from prolonged sun, UV exposure and changing weather conditions. Bitumen Aluminium S1 Reflector provides a highly reflective, UV-resistant silver coating specifically suited to exposed bituminous surfaces and torch-on waterproofing membranes.
For the best result, follow a complete maintenance process:
Inspect the roof → repair waterproofing defects → correct drainage problems → clean and dry the surface → treat fungal or algae growth → apply two full coats of Bitumen Aluminium S1 Reflector → allow 16–24 hours between coats → inspect the roof regularly.
A properly maintained roof system helps protect the waterproofing membrane from prolonged exposure to the South African sun and gives it the best opportunity to continue performing effectively. Visit your nearest Universal Paints Direct Outlet for advice on maintaining and protecting exposed torch-on roofing.
