Latest Guidelines from the NHBC on “Tiling bath and shower enclosures, wet rooms and bathroom pods”

Fourth issue November 2024

These guidelines are designed to minimise the risks of leaks within the areas covered by the scope of the document. To minimise the risk of leaks the NHBC guidelines stipulate specific requirements for any waterproofing systems (tanking) that may be used. These requirements are listed in table 2 of the document. The table covers liquid applied, flexible sheet systems and watertight boards and specifies the assessment requirements for each system. Liquid applied systems for example,  should comply with the requirements of EAD 030352-00-0503.

The full EAD 030352-00-0503 system also includes the use of the approved ancillaries e.g.  reinforcement tapes, gaskets, collars etc. as well as tile adhesives.

Where power showers are used, or for wet rooms, the requirements are clear that only systems listed in table 2 or otherwise separately assessed by NHBC are to be used. The permissible substrates for these areas are listed in table 1. Note substrates that are not listed, such as brickwork or blockwork should be over-sheeted with an approved board system.

Where power showers are not used then moisture resistant plasterboard (type H) or other proprietary board systems are permitted. However, these systems should be installed in accordance with the substrate system manufacturer’s advice. For example, the data sheet for Type H moisture resistant plasterboard from British Gypsum, states that, for areas subject to “repeated and persistent wetting”,  “a suitable proprietary tanking system” should be used prior to tiling. This guidance is in line with the current UK British standards BS 5385. It is important to recognise that NHBC states that, where waterproof tanking systems are used, they should meet the requirements of table 2  (Waterproofing system criteria).

Note: A power shower is defined by NHBC as having a flow rate above 12 litres/minute.

For walls which surround a bath where a shower is not fitted then the substrate should be suitable for the application and moisture resistant.

To help to reduce the risk of water penetration through the tile finish NHBC recommend the use of water-resistant adhesive and grout. However, it is important to recognise that the use of a water-resistant adhesive and grout is no substitute for a waterproof tanking system as clearly stated in BS 5385 Part 4.

A list of all the EAD certified products can be found in the EOTA directory ETA database | EOTA.