From January this year, major new regulations have been brought in that require waterproofing in wet areas in new build properties, covered under the NHBC warranty. In this article, Lewis Lupton, ARDEX Group UK head of training, explains how you can avoid falling foul of these new rules in your work.
The NHBC (The National House Building Council) are the UK’s leading provider of warranty and insurance for new homes, and have implemented new tanking requirements for their members, covered under their “Buildmark” 10 year Guarantee.
This means that any new home built in the UK (with foundations laid from 1st January 2025) will require that tiled wet areas are to be waterproofed with an EAD certified system, to be covered under their warranty scheme, if installers are tiling either:
- Shower over bath OR shower with shower tray, with standard flow rate less than 12 litres per minute – WHEN the substrate manufacturer’s guidance advises a tanking system is still required, or the substrate has not passed NHBC Table 2 assessment requirements.
- ANY shower over bath OR shower with shower tray, with a flow rate exceeding 12 litres per minute.
- or ANY wet room (fully tiled wall and floor, shower area).
Previous proposals suggested that ALL tiling in wet areas needed to be tanked with an appropriate tanking system. This was watered down (pardon the pun!) following extensive consultation with key housebuilders to include only those wet areas with showers with flow rates more than 12 litres per minute (rare in the UK) or any wetroom.
Critically, however, as per Point 1, tanking is still required in wet areas with showers with standard flow rates less than 12 litres per minute, when the substrate manufacturer’s guidance advises a tanking system is still required – or the background has not passed NHBC Table 2 assessment (see below). In other words, the manufacturer of the substrate must deem their product as suitable for use in wet areas, or tanking will be required in all situations.
This means that most common tiling substrates (used by housebuilders), such as gypsum plaster, gypsum plaster board and even moisture resistant plaster boards, will still require tanking with an EAD-certified system.
Table 2 tanking systems
The NHBC Table 2 tanking systems criteria for bathroom/wet room and power showers areas, including bathroom pods fall into three product types: liquid applied, flexible sheet and watertight boards.
Liquid applied products should be UKCA, UKNI or CE marked to EAD 030352-00-0503 “Liquid applied watertight covering kits for wet room floors and/or walls with or without a wearing surface” and include products like BAL Waterproof 1C one-coat ready-mixed tanking system (EAD certified with ETA-24/1129) or ARDEX WPC two-part waterproofing protection system (EAD certified with ETA 15/0458).
Flexible sheets should be UKCA, UKNI or CE marked to either: EAD 030436-00-0503 “Watertight covering kits based on flexible sheets for wet room floors and/or walls” or EAD 030400-00-0605 “Waterproofing kit based on polymeric membranes for in- and outdoor walls and floors or wet areas and swimming pools”.
Watertight boards should be UKCA, UKNI or CE marked to EAD 030437-00-0503 “Watertight covering kits based on inherently watertight boards for wet room floors and/or walls”.
According to the NHBC guidance:
“Tanking systems should form an impervious waterproofing layer, behind the tiles to prevent the ingress of water/ moisture into the substrate and structure.
“All junctions should be appropriately sealed e.g. between the wall and shower or bath, wall/floor junctions in wet rooms, including any penetrations, etc. to ensure a watertight enclosure is formed in accordance with the technical approval.
“Tanking systems should be applied in a uniform layer, prior to any wall or floor tiling. Liquid applied solutions or membranes should be appropriate for the substrate.”
To comply with this guidance, BAL have launched some new ancillaries, including BAL Waterproof 1C Tape, BAL Waterproof 1C Matting and BAL Universal Sealant and Adhesive that can be used in conjunction with BAL Waterproof 1C one-coat waterproofing system to achieve EAD compliance.
Liquid applied systems and appropriate tiling ancillaries
When selecting your EAD-certified waterproofing product for NHBC new builds, it is important to note that EAD certification also requires the use of compatible and approved tile adhesives, with each approved EAD waterproofing system. This means you must use the tile adhesives as specified in that particular EAD certification document!
BAL and ARDEX have multiple approved options from our existing core range of adhesives, that can be used with BAL Waterproof 1C and ARDEX WPC.
General waterproofing
Aside from NHBC requirements, British Standards clearly state the importance of waterproofing installations such as in BS 5385-1:2018, which states ”In wet areas, e.g. showers, wet rooms and steam rooms, substrates should be protected with a suitable proprietary tanking membrane system.”
It is important to remember that no tile, adhesive or grout will prevent water from travelling through to backgrounds, potentially resulting in unpleasant damp odours, persistent black mould, and even total installation failure.
That is why the use of a waterproofing system, such as the EAD approved BAL Waterproof 1C or ARDEX WPC, should be used to provide complete protection against water ingress, protecting backgrounds from water damage, degradation and decomposition.
Additional advice on waterproof tanking system requirements for domestic and commercial wet areas can be found by speaking to our technical support managers or calling our technical support helpline – 03330 030106.
