houses of parliament

Case Study / Waterproofing 

Houses of Parliament, London

A new basement was being built for this famous London Landmark

Houses of Parliament

MacLennan were employed by Shaca Construction Ltd to come up with a guaranteed basement waterproofing system for a new build basement at the houses of parliament.

MacLennan surveyors were engaged to carry out the site survey which would then enable MacLennan Waterproofing to specify the necessary work needed to meet the requirements of this project. The MacLennan cavity drain membrane waterproofing system, along with Maclennan external waterproofing system, was accepted as the most appropriate system that would provide the necessary protection from water ingress.

The use of Maclennan's Polyprufe spray-applied waterproof coating system was to be applied to the roof deck.

Houses of Parliament
Houses of Parliament
Houses of Parliament


The MacLennan team designed an external waterproofing system with an internal cavity drain and a polyurea roofing system to guarantee it was waterproofed to a high standard. An 8mm ventilated cavity membrane was installed from floor to ceiling, then a lime inhibitor was applied to the floor area followed by a 20mm membrane and drainage system.

The roof deck was coated with MacLennan Polyprufe primer and polyurea, then a drainage membrane was applied on top.

Maclennan engineers had to adhere to stringent guidelines while working in this security-sensitive and historical area. All cavity drain basement waterproofing installations systems are covered by the MacLennan guarantee.


The final outcome ensured a waterproof basement that complies with BS8102 2009 and was guaranteed against water ingress.

The whole contract was designed and carried out by MacLennan under their insurance cover and PI.

The whole system was guaranteed by MacLennan.


“The Palace of Westminster, better known today as the Houses of Parliament, is the oldest royal palace in London, a world heritage site and one of most recognised buildings in the world. Built on the site of a medieval palace, and possibly a Roman Temple dedicated to Apollo, the palace has been in continuous use since the first half of the 11th century. Today the oldest existing part of the Houses of Parliament is Westminster Hall, dating back to the reign of King William II“

Houses of Parliament

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