A structure with a flat concrete roof is very solid and an excellent building design. Flat roof waterproofing normally consists of 4mm thick modified bitumen torch bonded system that has traditionally proved the most successful and best value for money products in South Africa since 1980.
If the waterproofing is installed properly at the time of construction, the life expectancy of the waterproofing layer could easily last in excess of 20 years. A well installed good quality system could even have a life expectancy of 30-40 years. Often the reason for leaks to waterproofing is due to minor cause which is easily repairable and may not necessitate replacing of the entire waterproofing layer.
The most common cause of leaks on waterproofing that is in good condition include:
- – Minor delamination of seams.
- – Splitting of membrane to internal and external corners.
- – Waterproofing pulls loose where it seals into outlet pipes.
- – Failure of flashing to turn ups around perimeters.
- – Defective waterproofing around pipes and other penetrations.
- – Damage to waterproofing, especially by other trades (plumbers, electricians, cable installers etc).
- – Blocked outlets due to dirt, leaf litter or bird foul.
Looking after waterproofing can be compared to looking after a car. It is quite possible to drive your car for 50 000 km without a service. However, the lifespan of an engine is shortened if oil and filters are not changed. Likewise the waterproofing on your roof will easily last for 10 years without maintenance. However during that time minor defects could occur to corners, laps, protrusions and outlets.
A typical example is that an electrician may have drilled a hole through the waterproofing and installed cable clips with nails to keep the new wire in position. This will cause leaks and damage to the inside of your property. The protective aluminium paint layer will also not last 10 years. This is an excellent coating but it does weather and leaves the bitumen exposed to the harsh UV rays of the sun. The bitumen oxidises and starts to break down prematurely.
Flat Roof Waterproofing Maintenance
It’s advisable for the home or building owner to do an inspection on their flat roof at least once a year. Even a non expert untrained eye will easily pick up problems like blocked outlets and obvious damage to the waterproofing layer.
However, every three years the services of a professional waterproofing contractor should be engaged. Trained workmen will know exactly what and where the possible problem areas are and rectify them accordingly. Thus, ensuring the best chance for your roof to remain trouble free until the next inspection.
Careful inspection and repair to the existing waterproofing layer by trained workmen. The completed repair and overcoating job which will substantially extend the life of the waterproofing system.