Tag Archives: NHBC

New NHBC Basement Standard – 5.4 Waterproofing of Basements and Other Below Ground Structures.

Last week NHBC released one of their periodic ‘Technical Extra’ publications, and this edition exclusively deals with the waterproofing of basements and other below ground structures.

As I understand it NHBC have approximately 80% of the structural warranty insurance market, and so they have felt the effects of basement waterproofing failures more than any other.  More specifically, since 2005/6 they have spent within the region of £21m on remedial basement waterproofing. Continue reading New NHBC Basement Standard – 5.4 Waterproofing of Basements and Other Below Ground Structures.

Defects, Defects and Defects (BS8102).

As intimated in this post, British Standard 8102 Code of practice for the protection of below ground structures against water from the ground, is the primary design guide which we and others rely upon in our work designing and installed structural waterproofing systems. As an ‘approved code of practice’ it has an elevated legal status versus other design guides and hence its importance.

One of the key considerations listed is that of defects and remedial measures. In essence designers should assume the risk that any given waterproofing system might not be installed defect free, with risk of defects being associated either with workmanship or the products installed. Continue reading Defects, Defects and Defects (BS8102).

The Times They Are A-Changin’

As a contractor we are kept busy in part by the remedial basement waterproofing work that we undertake. To be fair this is something that we specialise in and so we may be approached with problem basements more than your average waterproofing contractor, but case in point, I’m writing this sat outside a property in Didsbury, Manchester, just waiting for a general contractor to arrive so that we can form trial holes to determine the build up of an external tanked deck, above a basement, which is causing issue in habitable apartments.

This is typical, and at the time of writing we have something like eight remedial waterproofing projects either on site or in planning. We are just one contractor.

So what’s going wrong? This is a question worthy of a long and separate post, but in brief, designs may be produced by those that often don’t have the requisite knowledge, spurred on by suppliers who’s primary interest in some cases is getting specified and selling product, with systems then being installed by inexperienced non-specialist contractors and problems ensue. No wonder.

‘Luckily’ at least for homeowners, where new homes are concerned these are usually covered by a ten year structural warrantee / insurance policy provider. These include NHBC (National House Building Council), Premier Guarantees (they also run the LABC scheme), and formerly Zurich. While Zurich no longer offer a policy, it’s less than ten years since they stopped and so there are still policies in effect.

A failure in a structural waterproofing system, in a house with this specific structural insurance, is generally covered under the policy, so again ‘luckily’ the cost of remedial works would be covered by the insurer.

I say ‘luckily’ because no homeowner ever feels lucky to suffer basement issues, distress would be a better description.

So in any case, insurance companies seek to manage their risk (spend less on claims) and at the same time to raise standards in house building, so that consumers are better served. Win win.

So what is the result of all of these basement failures? That’s right, standards have and are being updated.

I was employed a couple of years ago by Premier Guarantees to write their technical standards for basement waterproofing, and have presented to multiple teams of their building inspectors on what causes issues and how they can be prevented.

Following this, NHBC perhaps in some small way seeking to match the competition, are now updating their standards which we expect to be released early 2015, and they have been running a basement campaign with a view to educating their clients the house builders, as to what the issues are and why they are being addressed.

The major house builders should have a reasonable understanding in my experience because in many cases we’ve remedied issues for them direct.

So, the existing paradigm is changing. It is moving away from design and installation by non-specialists, towards the likes of us that do it day in day out, and know what is required to ensure no issues.

Exciting times.

J

For reference:

NHBC basement article

My work on the technical standards for Premier