Introduction

This book describes how to construct floors and walls in wet rooms to comply with the provisions of the 2010 Building Regulations (Ministry of Transport, Building and Housing, 2010) which relate to watertightness and water- and dampness-induced damage.

Background

Wet rooms are among the most critical rooms in a building because they are subjected to direct water exposure and high relative humidity, often exists for long periods.

Furthermore, any leakages may result in serious secondary damage to surrounding construction. The materials and construction shown in these Guidelines are well supported by experience. Construction carried out in accordance with the guidelines in this book can be relied upon to meet Building Regulation provisions for wet rooms, (particularly those concerning watertightness) and to produce constructions with satisfactory lifespans. Hence, no further documentation is required beyond these guidelines.

Scope

The Guidelines apply to new buildings, to new wet rooms in existing structures, and to the renovation of existing wet rooms.

A wet room is defined as a room exposed to water or high relative humidity. These typically include bathrooms, utility rooms, washrooms, and catering kitchens. Rooms with floor gullies are always classed as wet rooms because the floor gully is anticipated to be used and hence water exposure is expected.

Kitchens in dwellings are not considered wet rooms.

These Guidelines primarily deal with wet rooms built on site. However, provisions for wet rooms built as shower stalls or assembled from prefabricated units are also included. Furthermore, several issues are mentioned which require documentation prior to choosing and using prefabricated units or shower stalls.

The Guidelines do not address aesthetics, looks, nor prices. However, it is advisable to factor in total economic considerations into the design of a wet room (i.e., both capital costs and future operational costs).

A distinction is made between wet rooms with:

water exposure affecting both floors and walls (e.g., bathrooms and catering kitchens)
occasional water exposure affecting floors (e.g., toilet rooms, utility rooms, and laboratories)

In dwellings, all rooms containing a shower or bathtub are considered wet rooms. The only exception is prefabricated shower stalls (for example installed in kitchens or bedrooms as a temporary emergency measure in old dwellings without bathing facilities). If a shower stall is installed as a permanent solution in a separate room (potentially with a toilet and a washbasin), the room is classed as a wet room and must comply with the appropriate provisions.

Walls in toilet rooms, utility rooms, laboratories, etc., not subject to direct water exposure or major moisture exposure are not classed as wet room walls. Utility rooms and toilet rooms without floor gullies are not classed as wet rooms, but for hygienic reasons, floors in toilet rooms should be constructed as wet room floors (i.e., they should be watertight and easy to clean) (see Table 2 in Section 1.9 Planning, Design, and Construction).

Using the Guidelines

Where the word must is used in these Guidelines, it denotes a requirement that must be complied with. The word should denotes a recommendation which can be deviated from. If choosing to deviate from a recommendation, one should carefully consider the associated consequences, including whether there is sufficient documentation for the desired solution and whether strict supervision or control is required to avoid errors and omissions.

If, in a specific construction project, reference is made to specifications and drawings from these Guidelines, they should be adapted to the specific project.
Recommendations in these Guidelines can be used for designing and constructing wet rooms as follows:

Read Sections 1 and 2 carefully. Section 1 details basic requirements and recommendations while Section 2 describes general issues concerning choice of materials and constructions. Initially, it will be sufficient to gain an overview of the various construction types detailed in the remaining part of the Guidelines.
Determine the load class of the wet room based on the building in which it is located and its anticipated level of usage (see Section 1.6, Load Classes).
Start with Section 1.9, Planning, Design, and Construction, which reviews the planning, positioning, and layout of wet rooms and special provisions for people with physical impairment. This must always be considered, regardless of wet room usage. Determine the boundaries for wet zones and humid zones (see Section 1.5, Wet Room Zones).
Select constructions according to load class, thus accommodating the requirements for construction performance (see Section 2, Choice of Materials and Constructions – General Considerations). Select a floor construction from Table 3 in Section 3.1, Combinations of Floor Constructions and Waterproofing Systems and select a wall construction from Tables 6 and 7 in Section 4.1.2, Combinations of Wall Constructions and Waterproofing Systems. Constructions can be designed based on the detailed review of constructions in these Guidelines.
Select facing and/or surface treatment based on the constructions and load classes chosen. Try selecting the facing first, which will reduce the floor and wall construction options.
Complete floor and wall design once the floor and wall covering have been selected. The important thing is for the construction and surface covering to be compatible, and that the overall construction is applicable in the given load class. Furthermore, the general issues relative to floors and walls must be considered (see Sections 3, Floor Constructions and 4, Walls).
Construct ceilings, joints, and plumbing installations in accordance with the guidelines in Sections 7, Joints and Ceilings and 8, Plumbing Installations.

Several figures and tables in the Guidelines state the load classes in which the specific solutions can be applied (see Table 1). Load classes apply to floors and walls in wet zones and walls in humid zones.

Solutions marked in green and yellow can be applied. Please note that solutions marked in yellow can only be applied if the conditions specified in the figure or table text are met. The red colour indicates that the solution is unapplicable in the respective class.

Table 1. Colour marking of load classes in these Guidelines. (L: Low, M: Middle and H: High.)

Load Classes	Meaning
	Not applicable
	Solutions marked in yellow can be applied in load classes L and M if conditions specified in the figure or table text are met
	Only applicable in load class L
	Only applicable in load classes L and M
	Applicable in all load classes

Both design and construction work should be subjected to quality assurance (see Annex A. Checklists for Design and Construction). Furthermore, guidelines should be prepared for daily use and maintenance (see Annex B. Daily Use, Maintenance, Inspection, and Repairs).

Annex C. Terminology explains some of the technical terms used.