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Waterproofing a flat roof – Badly neglected IBR flat roof in The Reeds


The client just bought this property with a badly neglected Ibr flat roof in The Reeds and the roof urgently needed some TLC. As part of the sales agreement, the cost of restoring the roof would come out of the sales price. In order to be fair to both parties, the roof was thoroughly inspected.


On close inspection, the consultant reported that it was badly rusted because the roof was since the construction of the property never painted. It was apparent that quite a lot of fasteners worked themselves loose and it might even be that the roof structure was compromised. Unfortunately, a flat roof does not lend itself thereto that the structure could be inspected. Furthermore, fascia boards were missing


Having to work on a badly neglected roof is very challenging. As soon as one starts problems jump at you one after the other. Here is not only a rusted roof but it could be that it’s not only on the surface. Then the wooden structure could be not up to standard anymore because of fasteners that worked themselves loose.

Possible outcome

Having loose fasteners like this will let water into the roof. One will find an accumulation of damp witch compromise the ceiling boards and electrical wiring inside. Letting the situation go on this way one will find that mould will start growing inside the roof (all because of the moisture). This leads to medical expenses, the imploding of the roof and eventually, the building is at risk.

Suggestion to remedy the situation

The suggestion was that all rust be removed and fasteners replaced where necessary. IBR sheets not salvageable must be replaced. A coat of rust repellent paint (also called Anti Rust paint) must be applied to the whole roof and not just the affected areas. Only then can fasteners, joints and plumbers’ vents be waterproofed with membrane cloth. A good coat of UV resistant paint can finish off the job.

Decision with customer/owner

Because of the situation, the roof was in the parties had no choice but to agree.

Work done 

After thoroughly cleaning and removing all surface rust (luckily it was only that), the fasteners could be tackled. We were able to do that without having to replace any wooden structure. A good application of rust repellent pint followed in order to stop rust from reappearing. Each and every fastener, as well as all joints and plumbers vents, were waterproofed with the membrane. The final stage was to apply a couple of layers of UV resistant paint to finish the whole process.

Rusted IBR flat roof
Rusted IBR flat roof
Rusted IBR flat roof, loose roof screw
Rusted IBR flat roof, loose roof screw
Waterproofed and painted flat roof
Waterproofed and painted flat roof 

Waterproofed and painted flat IBR roof
Waterproofed and painted flat IBR roof


A well-executed plan always leads to a better than expected result. Here it’s no different, the roof was saved from complete redone and came out perfect. It will definitely withstand the weather for quite some time.


After thoroughly cleaning and de-rusting the roof it was apparent that it still had some life in it. Waterproofing a flat roof is a gigantic task in itself but after painting it with UV repellent paint of the new owner’s choice of colour it is good to go for a long time. The occupants can now enjoy their new residence and feel safe under a properly maintained roof.

Tremco’s highly qualified team used the three golden rules: Preparation – Application and Product = 100% Perfection.