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With a population of over 8.17 million people, the city of London, England continues to grow. The most recent census, released in 2012, reported a population . This makes London the fastest growing city in England.

The population boom has contributed to an increased population density, with limited space for building new homes. With no room to grow outwards or permission to build upwards, many people outgrowing their current homes have chosen to expand downward, which can sometimes triple the size of the street level home. In the , one such home faced the difficult task of constructing their 8 metre (26.25 foot) deep basement through water saturated sands and gravels into heavy London clay. Another challenge was building the basement with underpinning retaining walls, spanning 7.5 metre (24.6 foot) vertically, in permanent condition.

The engineering firm taking on the project was with considerable expertise in the complex fields of foundations, underpinning and piling. Using their experience and expertise in similar situations, they opted to use to permanently protect the concrete structure from water ingress.

“The flexibility and workability of the enabled a number of construction techniques to be employed which best suited the ground conditions and engineering requirements for each element of the project,” says Abbey Pynford divisional manager Lewis O’Connor.

The basement was constructed using �Ӱ�‘s and ,  a two-layer joint protection system.

The �Ӱ� system creates two layers of protection for the joints, with the second layer constructed from inside the completed structural shell of the basement. This increases quality management as the environment is controlled to be relatively clean and dry. The joints can be inspected pre- and post-grouting and any defects fixed.

Mr. O’Connor adds “The �Ӱ� products facilitated a very high degree of construction quality assurance, not possible with other products in the same circumstances.”