Tech Update: Lift pit tanking details

1. Introduction

This guidance provides a solution for the structural waterproofing of lift pits, on sites where there are no other structural waterproofing requirements (i.e. no basements or semi-basements and only a lift pit) and therefore the need for a Certified Surveyor in Structural Waterproofing to be engaged will not be necessary.

However, where a scheme contains a semi-basement or full basement scenario, the functional requirements of Section 2 of the Technical Manual prevail and a Waterproofing Specialist must take responsibility for the overall design liability of the waterproofing system, including any lift pits. The Waterproofing Specialist must have appropriate professional indemnity cover which covers their business activities. They must also have an understanding of hydrogeology and soil mechanics and hold a relevant professional qualification i.e. Certificated Surveyor in Structural Waterproofing (CSSW).

Please note these designs still require, additional information to be gained by our Risk Management Surveyor in order to fully mitigate our insurance risk on a site by site basis.

 

2. Lift pits constructed with masonry walls

 

masonry-lift-pit-tanking

 

For this situation our Risk Management Surveyor will need to gain the following information, for appraisal:-

  • A copy of the structural design for the lift pit, to check it meets the above minimum criteria.
  • Details of the 3rd party accreditation (BBA or similar) for the cementitious multi-coat render system, for appraisal.
  • Details relating to points A, B & C above, for appraisal.

Where the construction of the lift pit deviates from these minimum requirements, a CSSW Waterproofing Specialist, must be employed to design the structural waterproofing.

 

3. Lift pits constructed with concrete walls

 

lift-pit-tanking

 

For this situation our Risk Management Surveyor will need to gain the following information, for appraisal:

  • A copy of the structural design for the lift pit, to check it meets the above minimum criteria.
  • Details of the 3rd party accreditation (BBA or similar) for the cementitious multi-coat render system and hydrophilic water stops, for appraisal.
  • Details relating to the junction between the DPM and lift pit wall to ensure water tightness, details of how service penetrations are to be sealed and how any fixings are to be installed through the cementitious multi-coat render to ensure water tightness, all for appraisal.

Where the construction of the lift pit deviates from these minimum requirements, a CSSW Waterproofing Specialist, must be employed to design the structural waterproofing.

 

This article provides guidance on suitable Lift pit tanking details. It is important that all workmanship carried out during construction be completed in accordance with the relevant tolerances.

This article covers:

  • Introduction to lift pit tanking details
  • Lift pits constructed with masonry walls
  • Lift pits constructed with concrete walls

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Every care was taken to ensure information in this article was correct at the time of writing. Guidance provided does not replace the reader’s professional judgement and any construction project should comply with the relevant building regulations or applicable technical standards. For the most up to date LABC Warranty technical guidance please refer to your risk management surveyor and the latest version of the LABC Warranty Technical Manual.

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