Waterproofing Historic Basements & Conversions

If you're thinking of converting or refurbishing an existing basement or cellar structure that's disused or prone to flooding, MacLennan can help. Whether you want to transform the space to a new wine cellar, office or even a bedroom, we'll help to ensure it's watertight.

MacLennan carry out basement conversions every week.

We convert unused, damp or flooding basements and cellars into basement gyms, cinemas, swimming pools, bedrooms, flats, kitchens and much more.

Our expert team of waterproofing specialists will ensure your basement or cellar is permanently watertight. Whether we need to make a site visit, design and specify your waterproofing system, or work from pre-existing architectural plans, we'll deliver the best solution to meet your requirements.

When we come to the site to design your waterproofing system, we'll supply you with a comprehensive report and drawings detailing exactly what we propose to do. If we carry out the work, then we'll accept the design liability giving you peace of mind. As experienced waterproofing specialists, we work with an array of waterproofing systems fit for existing basement and cellar structures.

Waterproofing systems for existing structures

Get in touch with our technical team today!

MacLennan are experts in designing, installing and guaranteeing waterproofing systems for over 30 years.

Basement Dig out Holland Park

The cavity drain membrane system is one example and requires very little preparation as it is mechanically fixed and not designed to come under water pressure. However, if the basement / cellar is tanked this would cause additional stresses to the walls from hydrostatic pressure and this could lead to the tanking system failing.


MacLennan has the experience and knowledge to know exactly which system will fit and work best for your basement conversion project. The good thing about our systems is that when the membrane has been installed, no additional stresses are caused because we are allowing the water to come through the wall, down the membrane into a channel where it with either be pumped away using a sump and pump with battery back up or it will naturally feed into a soak away. The channel is critical and yet a great many systems are installed without the channel so are not serviceable and do not comply with BS8102.

Once the membrane has been installed on the floor and walls, you then get a choice of how you want it finished, whether it’s a standard screeded floor and dry lined walls to under floor heating and fancy marble faced block-work.



MacLennan can cater for all needs and requirements, we also specialise in sympathetic historical building waterproofing.

MacLennan is renowned in the country for excellent customer service and attention to detail. We offer a membrane system that comes with a quick installation to allow complete basement conversions on time and on budget. Contact MacLennan now and let us handle your basement waterproofing. We are confident in our services and have been for the past 30 years. To prove this, we offer a rolling 10-year insurance backed guarantee which covers design, installation and materials. Most guarantees are from manufacturers and do not cover design or installation. The MacLennan guarantees give you complete cover and peace of mind.

MacLennan are accepted by banks and mortgage lenders and insurance companies nationwide. What else are you waiting for?

Cavity Drain System

Why should I work with MacLennan?


We Design, supply and install. There's no split responsibility with MacLennan.


MacLennan live and breathe waterproofing, have a look at one of our free CPD seminars and find out!


MacLennan has the most comprehensive guarantees and insurances in the industry.

What are the main causes of water in a structure?

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0330 3200 240
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