Waterproofing for the ages

For decades, mastic asphalt has proved its credentials as an underground waterproofing membrane that can last a lifetime, as the Mastic Asphalt Council explains.

The fluctuations of the water table – and the devastating effects high water tables can have in flood risk areas – is something known to many, but it’s important to take preventative measures to avoid water ingress. If a building is in an area susceptible to groundwater flooding, it’s vital that it is protected from the ground up – and the best defence possible can be provided by one of the world’s most traditional materials – mastic asphalt.

Floodwater can take time to build-up but when it rises, the water table in the ground surrounding a building can create hydrostatic water pressure. This water pressure is exerted on the floor and walls of the basement and can lead to water penetration through cracks, joints and structural weaknesses in the basement.

Without a tried and tested tanking system this water ingress can then lead to mould, decay, structural problems and other damp-related issues.

Tried and tested

Even the smallest leaks can lead to big problems, which is why it’s critical that specifiers choose a high performance solution that saves time, money and hassle. A long-lasting material, mastic asphalt has stood the test of time proving its quality as waterproofing membrane for preventing moisture penetration in many applications whether for roofing, paving or tanking.

To this day, large areas of London including the Houses of Parliament rely on mastic asphalt for protection against rising groundwater levels. This proven tanking system provides a continuous waterproof- ing lining to safeguard walls, floors and foundations. Unlike alternative products

and materials, mastic asphalt does not degrade and remains a reliable, low maintenance waterproofing solution throughout a building’s design life.

Application in practice

It’s always been a British holiday haven, but the county of Cornwall is not immune to floods, tidal surges and saturated ground, making it all the more critical that buildings are adequately protected.

Such was the case during the construc- tion of two luxury residential developments on a sloping site in Cornwall, when the contractor required a tanking solution with long-term durability for highly effective waterproofing protection. In order to seal the reinforced concrete retaining walls and floor slab at the site overlooking the beach in Polzeath, specialist contractor Premier Mastic Asphalt used 360 m2 of mastic asphalt to protect the building against aggressive ground conditions.

Jason Shields, partner at Premier Mastic Asphalt, comments on the project:

“Due to the level of the land, the contractor under- stood that mastic asphalt was the best product to use in order to create a water- tight barrier. The application went extremely well, with the only challenge being the inclement winter weather and the fact the company’s mixer and materials had to be lifted in.”

That wasn’t the first time his company applied mastic asphalt for tanking in the area – in fact, it has become a commonly used solution on a number of high-specifi- cation housing schemes across the region, as Shields explains. “Having installed mastic asphalt tanking in various locations all over the south west, we get a good sense of satis- faction knowing that we have provided and installed a well proven, traditional product,” he says.


Flooding issues caused by heavy rain, high tides and swollen rivers will continue to require management as extreme weather across the UK becomes the norm. But with correctly-designed houses and commercial properties protected by mastic asphalt, we can ensure that flooding caused by rising water table levels is history.

The Mastic Asphalt Council is the trade association for the UK mastic asphalt industry