Many factors need to be taken into account when specifiers, contractors or end users are selecting a suitable roofing system. These factors include considerations such as longevity, ease of application, sustainability, fire credentials and cost.

Cost is often one of the first considerations, but there are other factors to take into account beyond the initial quoted price. At the Mastic Asphalt Council (MAC) we see many examples where construction professionals have taken a very myopic view and chosen roofing products based on price alone.

Cases where the specifier or end user did not fully understand the limitations of the product, or chose to ignore them, simply to save money. This often leads to rapid failure and usually means that the building owner has to foot the bill for a second time.

It is often all too easy to take the short term view and look at initial installed costs of a product and the impact this will have on the project budget. On face value, some waterproofing membranes such as mastic asphalt might not seem to offer the best value for money. Fortunately, more and more specifiers are realising that they can actually find the best value for money and most sustainable solutions from tried and trusted waterproofing products such as mastic asphalt.

The true cost over the lifetime of a building is perhaps a more accurate reflection of the value of a particular product. For example, many systems might seem initially attractive from a cost per square metre point of view, but will then require relatively expensive refurbishment or replacement within a limited period of time. Sometimes only a few years.

The Building Research Establishment (BRE) has independently accredited mastic asphalt to last at least 50-60 years, but there are many cases of asphalt roofs providing effective waterproof protection for 80-100 years. For example, the rooftop of Buckingham Palace is protected with mastic asphalt and it has kept the building dry for well over 80 years. Mastic asphalt was also first laid at London’s St Paul’s Cathedral in 1906 and it provided well over 100 years’ of effective waterproofing before it needed replacement.


Lowest Life Cycle Costs Over 60 Years

When compared with alternative waterproofing systems, mastic asphalt can offer the lowest life cycle costs over a 60 year period, when the typical refurbishment and replacement requirements for each system are taken into consideration. For example, specifying mastic asphalt to protect a roof the size of a football pitch could cost £40,000 less than other waterproofing products over the lifetime of the installation.

It is the longevity and durability of mastic asphalt that makes it the best value solution. Though alternative waterproofing membranes may appear much better value initially, many of them have life expectancies of around 15-20 years which is only a third of the typical life expectancy of mastic asphalt.

Another consideration is that while some modern waterproofing products may provide impressive results in laboratory tests, they may perhaps not perform so well when installed and exposed to the rigours of UK construction methods and wet weather conditions.

Quality of Installation

It is also worth noting that the quality and reliability of any chosen waterproofing system is only as good as the quality of installation. The Mastic Asphalt Council ensures that every installer of mastic asphalt has trained and achieved an NVQ level 2 qualification in the mastic asphalt craft. Unlike many other systems, mastic asphalt is only ever installed by reputable and skilled crafts people.

Mastic asphalt is also easy to repair and maintain should alterations or damage occur. As mastic asphalt is seamless, any imperfections can be easily be found and repaired with a simple application of the material. This means there is absolutely no disruption to activities in the underlying building.

Furthermore, once mastic asphalt has reached the end of its life span, it can be recycled or used as roof screed, minimising the impact on the environment. The fact that mastic asphalt is UK manufactured also makes it very popular with clients.

Local Authority Research

The Mastic Asphalt Council has carried out research by surveys and in-depth interviews with local authorities UK-wide to gain a greater understanding of the awareness, perceptions and attitudes towards mastic asphalt and specifying waterproofing products in general.

This research revealed that with budgets being cut year on year, local authority specifiers are increasingly looking to specify products that offer better durability and lower costs over the lifetime of the building.

One of the respondents said: “I previously had a simplistic view that mastic asphalt was more expensive than other options. So it’s really surprising to learn that its life cycle costs are actually significantly lower.” Another said: “I wasn’t aware that mastic asphalt is independently accredited to last over 60 years. This reliability would certainly help to reduce the cyclical repairs that are needed on buildings, which in turn will help make our budgets go further.”

This article featured within the May 2023 edition of RCi magazine – click here to view the article.