Service Penetration Flooding

Job type: New build waterproofing systems
Location: North West, UK

This one wasn’t without its challenges...

• Beautiful newbuild house.
• Built on a low lying site which collected water following heavy rainfall.
• Clay ground (does not drain) encouraging water to perch and pressure on the basement structure.
• Land drainage installed but too high and ineffective (linked to septic tank with overflow that didn’t work).
• Concrete structure tanked externally (bitumen sheet membrane) and internally as a remedial measure using cement slurry tanking, both systems by builder, both failed.
• We were advised that problems with service penetrations (pipes/cables running through basement walls), had been addressed, but these turned out to be the main cause of trouble in the basement.
• Main contractor went bump leaving homeowners to figure out what to do.

Lots going on here

Others had been invited to price for remedial works, and I understand stated on inspection, that they could address it all without really explaining how.  

One thing I understand from nearly 20 years of dealing with problem basements, is that where issues are complex, you’ll never digest all the information on the spot and come up with the solution there and then.  If you do you risk missing something.  Key in the design process is to collect the info, do a desk study and then THINK to develop your design (the right design).  This is what we do every time but from homeowner comments, this was a noted difference between Trace and others.

We had noted ingress through service penetrations when we inspected, but were told that land drains had been retrofitted externally, and that these were now not such a problem.

Irrespective, we advised that it would be unlikely that we could completely seal the service penetrations, as others had already tried and they were a mess of different materials, but that we would install cavity drainage waterproofing internally, to collect and remove penetrating water using pumps, channels and cavity membrane.

The next thing is, we’ve started work on site and overnight there’s massive rainfall and the homeowners contact us early in the morning stating that the basement is flooding, so we dash over there and water is absolutely pouring out of the service penetrations, and there is essentially a moat around the property, meaning that the remedial land drains are doing nothing. 

So what do we do:

• Dig down externally to the level of the land drain.
• Fit a temporary pump to shift water collected by the land drain, thus taking pressure off the service penetrations to stop them leaking.
• Excavate externally around the service penetrations, granting access to form external tanking details.
• Formed internal tanking details around service penetrations.
• Installed internal cavity drainage as originally planned.
• External temporary pump left in place for six months until homeowner could arrange to link the land drain to a reliable/other outlet (not the septic tank).

This is what the homeowner said after we’d completed:

I cannot recommend Trace Basements highly enough. I had been facing basement problems with water ingress every time it rained. Multiple contractors had attempted to plug the leaks, reline the wall etc all of which works for a little while with recurrence of the problems a short time later. James came in, took a little time to investigate, considered options and explained to us what was required. Both him and the rest of the team were very approachable. The work has been carried out to a very high standard. They went beyond the call of duty to help to the extent that they mobilised immediately to dry out the basement on an occasion where some heavy rain overnight left me with a basement under 2 feet of water. I was away but phone calls/text messages resulted in them coming in, clearing up etc. James even took away some of my electricals to dry off, making sure they worked before bringing it back. All in all, having self built and dealt with a myriad of contractors of multiple trades over the past few years, Trace stands head and shoulders above the rest.