Structural Waterproofing
This is the term that’s used to describe the technical job of assessing waterproofing requirements in a basement conversion and making sure that appropriate measures are taken to make the new living space waterproof.
Many general builders claim to understand the problem and how to address it, but in reality this is a specialist area, and unless you use someone with a full technical understanding, and appropriate experience, you could find yourself with an expensive conversion that is unusable. You then have to start getting involved in remedial work and disputes over who will pay to rectify the problem.
A Miss Is Is as Good as a Mile
In most areas of building, 99% effectiveness is an excellent result. For contractors following professional waterproofing procedures, 100% effectiveness is the only acceptable result. Proper waterproofing can’t be done by untrained labourers who have just been handed a waterproofing product. These products have to be used to exacting technical standards in order to be effective. Otherwise, the waterproofing fails despite the “right” products being used. So your contractor needs to have staff that they have trained in these techniques and who are supervised for quality assurance.
Look for the Logo
For the last 25 years the British Structural Waterproofing Association (BSWA) has been the professional body for competent companies doing basement conversions in London and elsewhere. It’s pretty fussy about who is allowed to join – for example, people who have been working in this area for just a few years are only allowed probationary membership and can’t display their logo.
Members are rigorously assessed and vetted, so the hard work has been done for you. If you’re concerned about a company’s competence in this area, look for the logo. It’s a guarantee that your contractor knows what they’re doing, is aware of all the available products and techniques and is trained in using them properly.
Unfortunately, people aren’t always scrupulous about pasting a logo on to their web page, so check on the BSWA’s website to ensure that the company you’re thinking of using really is a member. https://www.thebswa.plus.com/contractors.htm
Compliance with BS 8102
BS 8102 is the British Standard Code of Practice for works to protect below-ground structures against ground water. Your BSWA-certified contractor will be working to this code of practice when they carry out your basement waterproofing work.
As an expert contractor, they will survey the property to get a detailed understanding of the existing structure and the internal environment of the property. They’ll look at the external ground conditions and the flood risk before assessing which tools and techniques will provide an effective waterproofing system for your particular basement. They’ll also take a serious look at the risks of each option before discussing the way forward with you.
Finally, beware any uncertified waterproofing firm that tries to push one solution at you – it may be very well be the only one they know about.