The 90’s were great; it involved most of my time at school, then starting and completing both college and university, with a lot of building site work thrown into the mix during the ample holidays that you enjoy as a student. But what a time to be that age, and in Manchester…
Anyway, back then we, and I say ‘we’ but essentially I mean George/my M.D./Dad, was moving away from the traditional multi-coat cementitious tanking render systems, towards cavity drainage waterproofing systems, generally using three components:
1. Cavity drainage membranes, which are a plastic vapour barrier sheet with a dimpled structure, creating a small void behind/beneath the membrane allowing passage of water.
2. A pre-formed plastic drainage channel system brought in from the USA mid-90’s (we were the 2nd UK firm to use this and since the 1st no longer trades, have longer experience of it than any other) which all of the UK manufacturers now produce and supply.
3. An automatic sump pump system – plastic chamber installed into the ground containing pump(s) operated via float switches to turn the pumps on/off as the water level rises and falls.
Images courtesy of http://newtonwaterproofing.co.uk/
Simplistically the channel collects penetrating water and allows this to drain to the sump system, which continuously removes water, so that it cannot collect, stand and pressure on the dimpled membranes, which are always installed above the level of the channel.
The key to it all, is that if water cannot ever pressure on the membranes (because it is continuously removed by the pump system), then it cannot ever come past the membranes, therefore we know that if we get the drainage and sump system right, it will result in a permanently dry basement.
If we get the drainage/sump wrong and water pressure comes to bear on the membranes, this is a bad thing because those membranes are not capable of holding back a head of water, and the result will be penetration past the waterproofing, i.e. waterproofing failure.
Part of getting the sump pump system right, is having in-built redundancy, which (simplistically) means two mains powered pumps providing mechanical redundancy, and an effective battery back-up system to provide protection in the event of a power cut. NB: there is some complexity to the design of such systems but this is a good baseline.
Way back when we started, the norm was to fit 1x mains powered pump, and provide the client with an option, to fit battery back-up, covering them in the event of a power cut. If they did not take the option, that was at their risk.
Pretty quickly we recognised that with the money invested in residential conversions, and the implication upon that of a flooded basement, that battery back-up should not be an option, and that we as experts would better fulfil our duty of care to the client by including this and ensuring that clients were properly protected.
As a result today we would just include for battery back-up on residential conversion and in any case where we want to ensure no issue. As times have moved on we now use the same back-up 240v power system employed by the Ministry of Defence, and can offer control panels with diagnostics and telemetric dialler systems, remote web access monitoring and even self-start generators, this all because we know that getting the drainage aspect right is the key to our success and happy clients.
So, last week we attended the Property Care Association awards dinner (we got lucky) and I was speaking with a supplier of waterproofing materials (sump pumps/membranes/channels).
I had previously asked them publicly via social media why they were not offering battery back-up systems via their web-site, for all the reasons detailed above, which showed only a single option for a sump with 1x mains powered pump.
I did not raise it when we spoke but to their credit, they did. The comment was that it was a website update issue and that they did of course offer battery back-up systems (same comment as when I asked via social media).
What was surprising however is that I was also told of basement conversion specialists local to me, i.e. working around Manchester and Cheshire, purchasing lots of membrane and sump pump systems, but never with battery back-up, and when queried on it by the suppliers, their response was that ‘the clients would never pay for that’.
In my opinion this is poor waterproofing design and is a disservice to the client, particularly if the firms in question are not making them aware of the risks. It is not a total surprise because we are picking up work dealing with problem conversions and although it is not always the sole cause of the issue, it is not unusual to see sump pumps without battery back-up, this being one example.
This isn’t the late 90’s, it’s 2015, it’s not a massive sum of money in the scheme of a conversion, how can these firms claim high levels of service, yet go for ‘cheap’ and inadequate protection?
If you are looking at having your basement converted, whether you are in our area or anywhere else in the UK, please look at whether this includes battery back-up, and the terms and conditions (guarantees) if it does not.