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Underpinned Structures

These Newton Solution Sheets show the highest degree of waterproofing to a structure built with underpinning whilst also indicating the risks of a lower degree of waterproofing.

This type of structure has two inherent weaknesses as an earth retaining structure that is designed to be water-excluding:

  1. The walls are not as water-resisting as conventional reinforced concrete walls due to the sequencing of the underpins and so an internally applied Type A barrier membrane is required to seal the joints and provide a structure that is as watertight as possible.
  2. An external ‘Type A’ membrane system is possible but logistically and practically difficult, therefore a continuous external membrane cannot be achieved.
  3. There are non-compressed joints that promotes ingress of water between the concrete joints.

Download Newton Solution Sheets for Underpinned Structures

These downloadable Solution Sheets are a sample of the numerous waterproofing solutions for underpinned structures, and provide a comprehensive waterproofing specification tool including all key product information, from NBS Clauses to 2D details, CAD drawings and 3D drawings.

The Solution Sheets have also been scored on the Newton Waterproofing Index as an indication of our expert opinion on the likelihood that the design will achieve the required level of waterproofing.

Recommendations & Standards

Where possible, we would recommend a new reinforced concrete slab designed to BS EN 1992 (Eurocode 2) and that it is of sufficient mass and quality to resist heads of water pressure as recommended by BS 8102:2022. The only place that water will then be able to enter is at the joints, basically where the concrete isn’t.

Ensure the structure is as watertight as possible. Whilst cavity drain membrane systems can deal with high levels of water ingress, to extend the life of the system it should ideally only need to deal with seepage. If just one form of waterproofing is possible, a Type C specification provides the safest waterproofing design for existing structures or alternative forms of construction where Types A and B are impossible.

The Newton Waterproofing Index

The Newton Waterproofing Index (NWI) is a unique scoring system that accurately assesses the level of risk and potential success of waterproofing specifications. NWI scores are awarded by a panel of experienced waterproofing design specialists and reflect the chances of success of each specification.

For more information about NWI scores and how they can help with your project design, read our page explaining the Newton Waterproofing Index and how it works.

For more information regarding these solution sheets, or to find a specification suitable for your project, please fill out the form below or email our Technical Team at tech@newtonwaterproofing.co.uk.

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