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Waterproofing Metal and Concrete Roofs

Thermo-Shield Roof Coats deliver high-performance Waterproofing and °Cool Roof on Metal and Concrete Roofs.

Waterproofing Metal Roofs

Any warehouse owner will tell you, a leaking roof is a big problem. Poor 'design and build' is one of the reasons for leaks that lead to corrosion of purlin and beams, and in extreme cases the destruction of goods or expensive machinery. Throw in poor maintenance, bad waterproofing and such – a good recipe for a nightmare. That said, many people think waterproofing needn't be an important aspect of design and build of a metal roof. The narrow gutters, the apologetic down-pipes and drain-pipes, etc. suggest a poor design.

When it starts to leak, they start looking for the cheapest option. If not bitumen, a mix of acrylic coating and fibreglass (sometimes fibreglass mesh) is used to waterproof the joints. Heavy condensation leads to a lot of water on the roof, and the moisture gets trapped in the 'waterproofed joints.' This collected moisture and UV put together starts destroying the fibreglass mesh or flakes - leading to considerable rust and damage.

As most clients and contractors cannot tell the difference between UV-Resistant and UV-Stable, the cheaper UV-stable styrene acrylic coatings are always in high demand. Any coating can claim to be UV-stable with the addition of some 'stabilizers' – the UV stability just doesn't last long enough. Once corrosion sets in, it starts to spread like cancer, purlin and beams are the next to go.

Thermo-Shield® °Cool Roof Coat is ideal for protecting metal roofs as a complete weatherproof solution. It is a UV resistant coat to withstand the high UV and heat of the Arabian Summer, also has a low Tg value to withstand freezing conditions. We have roof references in the UAE – coating applied in the 90s, which has lasted for more than 20 years without any deterioration or decay.


Check all fasteners/ screws. Tighten the loose ones. If need to be replaced, use one size bigger self-tapping fastener.
Use 100% Blind Aluminium Rivets to reinforce the laps. Clean all the laps/joints manually.
We recommend the use of Polyurea for End-laps (Horizontal Joints).
Seal all the side-laps by embedding Hydro-Shield PF fabric in Thermo-Shield. Dab Thermo-Shield on the screw-heads as well.
Pressure Wash at 2500psi to clean the roof surface. This wash also functions as a water-leak test.
Airless spray apply Thermo-Shield in Two Coats to build 300µ DFT.

Why Polyurea on End-Laps and Gutters?

We recommend 100% Pure Hydro-Shield Polyurea to be applied at 2mm DFT on all end-laps. Polyurea has a high Tensile Strength of >2000psi and can withstand the movements. The common notion that Elongation of the coating will prevent joints from cracking open is so WRONG!

Once the roof is sealed water-tight, the rising Hot Air has to go out, if there are no ridge vents, the hot air will continue to push the roof cladding. Horizontal joints are the most vulnerable under tremendous pressure. 100% Polyurea is an excellent solution to deal with this issue. There's no need to do structural hara-kiri as seen on many roofs!

The Key Performance needed on End-Laps is Tensile Strength and not elongation. Do not trust contractors who claim that thermal shocks are the reason for the movements.

Do not believe anyone who blames the failure of waterproofing on Thermal Shocks. When Thermo-Shield Cool Roof Coat is applied on metal roofs, movements caused by Thermal Shocks can be completely ruled out.

It is the upwardly mobile hot air, which causes the significant movements. Call us, to discuss the Technical Details of Polyurea, Tensile Strength, and Waterproofing. Trust physics and nothing else when it comes to waterproofing.

Waterproofing Gutters

We also recommend 100% Pure Hydro-Shield Polyurea Application in metal gutters as most gutters in the region have water ponding issues. Polyurea coatings go through no changes in ponding water and retains its water-tightness. Please find out more about Waterproofing Gutters.

Waterproofing Concrete Roofs

Thermo-Shield® °Cool Roof Coat is an excellent product to build up a waterproofing membrane on flat concrete roofs. The recommended thickness is 1mm DFT; if there is no water ponding, 700µ DFT will suffice.

Old Flat Roofs usually have bitumen membrane or concrete tiles or a screed installed. A proper assessment has to be made to ascertain the condition of the roof. We have appropriate primers and coatings to ensure a succesful waterproofing installation. Always consult us or an approved applicator to get the technical details sorted.


Pressure Wash at 2500psi to clean the roof surface.
If there are cracks and damages, apply Hydro-Shield Cementitious Acrylic membrane at 2mm DFT.
Use an Airless sprayer or roller to apply Thermo-Shield in many coats to build 700µ to 1mm DFT.

Apart from waterproofing, Thermo-Shield Cool Roof System can significantly reduce Solar Heat Gain on the roof surface — creating a comfortable working space under the roof. If it is an air-conditioned facility, Thermo-Shield Cool Roof can help with Save Energy. For the record, Thermo-Shield® °Cool Roof has a High Solar Reflectance Index value, and Zero R-value.

We provide training to contractors and applicators. Get in touch with us.