New Build Basement Waterproofing – Design Strategy

New Build Basement Waterproofing – Design Strategy

On a  daily basis we field enquiries and queries about the best way to make a new build basement waterproof. The waterproofing method adopted for a new build basement is indeed a very prudent and essential consideration as failure to make the correct decision can have a major impact on the effectiveness of the system, the potential use of the basement,  the risk of consequential loss and avoiding liability dispute.

Implications of BS8102 for New Build Basement Waterproofing

In terms of a strategy for waterproofing a new build basement or and existing basement we think the best way to view a project would be with consideration to recommendations made by the BS8102 : 2009 code of practice for ‘The Protection Of Below Ground Structures From Water From The Ground‘with the particular regard to:-

• The type or types of construction and waterproofing i.e
  Type A (Barrier) protection
  Type B (Structurally Integral) protection
  Type C (Drained) protection
• Expect and design to expect a full head of hydrostatic water pressure where comprehensive site investigation regarding the geology, hydrogeology and topography both current and historical in relation to the below ground structure are not possible or the results are inconclusive.
• A “Waterproofing Specialist” should be included as a part of the design team so that an integrated waterproofing solution is created. All design decisions made by others that might have an impact on the waterproofing design  should be brought to the attention of the waterproofing specialist/designer or installing contractors. Final decisions and any recommendations should be approved by the specialist.
• Consideration should be given to the use of combined protection (i.e. Type A and Type B, Type A and Type C or Type B and Type C) where in a single system: a) the likelihood  of leaking is high. b) the consequences of leakage is unacceptable. c) additional vapour checks are necessary for a system where unacceptable water vapour transmission could otherwise occur.

Newtons Recommendations for New Build Basements

Newton System 500 is ideal for new build basements, and it fully conforms with BS8102:2009 regulations

At John Newton and Co. we believe that where possible the best combined system for a new build basement would be a combination of Type B and Type C Newton cavity drain membrane. In basic terms design and build the structure as strong as possible to form the primary resistance against water ingress but expect that some leakage may occur and install a contingency plan in the form of a Newton Cavity Drain Membrane System. We would advise against external impermeable membranes as a waterproofing element on their own or as part of a combined system which does not include a Type C element for new build basements for the following reasons:

• The use of external impermeable membranes may also be considered but with the important caveat that it potentially conflicts with the performance of water- resisting concrete. It is important to note also that, apart from the significant cost of membrane systems, their success depends on the highest quality of workmanship. The quality of the concrete surface, especially with bonded membranes such as bitumen sheeting, is critical and is not easy to achieve’ – IStructE document for ‘Design and construction of deep basements’.
• The judgement in the overview of the High Court case ‘Outwing vs.Weatherald’ agrees that ‘it is not reasonable or realistic to expect a bonded sheet membrane to be applied without any defects at all‘. Therefore if you incorporate a system which needs to be 100% defect free to work in your design and it fails you may be accountable.
• ‘Leaks caused by defects in external membranes are practically impossible to locate and repair, since the water invariably enters the structure internally through cracks or other vulnerable points, such as any movement joints, at some distance from the external defect‘.- IStructE document for ‘Design and construction of deep basements’.
• Because consideration should be given to the ‘form and feasibility of remedial work’ which means if there is a problem the ability to get back to the structure to diagnose and determine the cause and location and then rectify the problem. -BS8102 :2009
• Because consideration should be given to providing a ‘maintainable’ waterproofing system. – BS8102 :2009

There are of course other details in construction of a below ground structures like Podium Decks, Pile Caps, Intermediate floors etc which will require specific detailing with a combination of products and techniques all of which can be successfully dealt using products from the Newton range.

Guaranteed Installation from Newton Specialist Basement Contractors

Whether waterproofing a new build basement or an existing structure, we will always recommend that the system be installed by one of our registered contractors. If they are involved in the design work early enough and then undertake the work they will ultimately be responsible for both the design and the installation which means that they will give meaningful, insured installation guarantees for the work they undertake and with most of our contractors having suitable PI allowing you to delegate the full design liability for the waterproofing aspect of the project to them. They are approved installers of a number of waterproofing products an as such will, without bias, put forward a design using the system or systems which they feel will be the most suitable trouble free and effective in the given circumstances. As stated above the BS8102  calls for a waterproofing specialist to consult as part of the design team and this can be a Newton Specialist Basement Contractor.They are aware that it is usually not possible to nominate the waterproofing specialist in a competitive tender situation but still would appreciate the opportunity to put forward their design and costs at an early stage.

Structural Waterproofing Design Strategy CPD

Click here to read more about our RIBA Approved CPD, and to book online. The presentation will provide an insight into the successful techniques that are now being utilised in the waterproofing industry.

New Build Waterproofing Case Studies

Multi-Level New Build Basement, Edinburgh Newton System 500 Allows For Highest Level of Waterproofing Protection in the UK

Multi-level new build basement, Edinburgh

This New Build basement was split onto two levels and was constructed from reinforced concrete panels bearing off a structural raft. The construction was cut into a sloping site, so that the back elevations of the project were earth retaining. Newton Specialist Basement Contractor, Richardson and Starling curtain hung Newton 508 cavity drain membrane to the concrete panels using Newton MultiPlug fixings. Newton Basedrain was installed in a horseshoe formation, ensuring that any water entering the structure would be diverted. The installation of the Newton System 500 water management system allowed for the highest level of waterproofing protection in the UK, and Richardson and Starling were able to offer full design and installation guarantees for this major new build basement development. The design fully complied with BS8102:2009 regulations.

Multi-Level New Build Basement, Edinburgh – Read More and Download Case Study

Residential New Build Basement, Kent Protected Internally with Newton System 500 and Externally with Newton System 400

Residential new build basement: Newton System 400 used externally, Newton System 500 used internally

This expansive new build basement was designed to become an integral part of a historic manor house. Newton Specialist Basement Contractor, Gulliver Timber Treatments used Newton 410 Geodrain as a drained waterproofing layer underneath the slab. Newton 902 Primer was then painted on the vertical walls as a Type A waterproofing protection. Adjacent to the footings two 110 perforated land drains were installed wrapped in Newton Geofabric to act as a filtration layer. The secondary system installed was the internal Newton System 500 drained cavity system. The installation of the dual Newton System 400 and System 500 means that the structure itself is kept dry and the external drained layer moves any water away from the structure before it comes into contact with the retaining walls. Gulliver Timber Treatments were able to offer full PI on design and offer peace of mind to the main contractor and client with insured backed guarantees. The design fully complied with BS8102:2009 regulations.

Residential New Build Basement, Kent – Read More and Download Case Study

Further New Build Basement Waterproofing Advice and Registered Installers

Please do not hesitate to contact us at Newton on 020 7237 1217 or info@newton-membranes.co.uk for any technical advice you may have or if you require a list of Newton Specialist Basement Contractors in your area for a new build basement, or for waterproofing an existing basement.

This entry was posted in Basement Waterproofing, News • September 5th, 2011 • Back To Top