Guide to Conversion of Traditional Buildings

3.12 Sanitary facilities

Mandatory Standard

Standard 3.12

Every building must be designed and constructed in such a way that sanitary facilities are provided for all occupants of, and visitors to, the building in a form that allows convenience of use and that there is no threat to the health and safety of occupants or visitors.

3.12.1 Application of standard to conversions

In the case of conversions, as specified in regulation 4, the building as converted shall meet the requirement of this standard (regulation 12, schedule 6).

3.12.2 Commentary

The Technical Handbooks specify the number of water closets (WCs) or waterless closets, washbasins, changing places toilets, baths or showers and sinks required in domestic and non-domestic buildings. Many pre-1920 domestic properties were designed without separate toilets or bathrooms. If these properties have since been in domestic use, most will have already been upgraded to include a bathroom with a WC or a bathroom and separate toilet. However, the requirements to provide an accessible toilet from public areas and to provide a changing places toilet may be difficult to accommodate in the conversion of a traditional building. The space for such installations may not be available within existing accommodation without disrupting the character of the building’s more architecturally important rooms and spaces.

In addition to the provision of new sanitary facilities, the design, routing and installation of water supply, soil and waste drainage and ventilation to serve the facilities need to be planned carefully in order to avoid disruption and harm to historic fabric and cultural significance. Accommodating soil and waste drainage, for example, can be difficult to achieve within the thickness of an existing floor, and ‘boxing-in’ of pipework below a floor is unlikely to be an appropriate solution in more historic rooms. Similarly, the creation of vertical ducts within historic spaces can be disruptive to their character. Wherever possible, the installation of services to sanitary accommodation should be routed within existing voids and ducts.

Consideration should be given to access for installation and maintenance as many damp problems result from leaking, failing, or poorly installed services. Care should be taken, therefore, to route services in a manner that reduces the risk of disrupting historic fabric and features if future maintenance is required. Although accessible service routes have the potential to be more visually intrusive, they can be accessed, removed or altered in the future with minimal disruption to the building.

3.12.3 Issues to be considered

Typical risks in the conversion of historic/traditional buildings

1. Provision of sanitary facilities and accessible toilets

Where additional toilets and bathrooms must be provided for a conversion, it can be difficult to find adequate and appropriate space for them without compromising the main rooms of the building. In particular, the provision of an accessible toilet and/or a changing places toilet, accessible from public areas (not en-suite) can be disruptive to the historic character of key spaces.

The installation of a changing places WC may have implications regarding the requirement for accessible routes, existing door clear widths, lift sizes, and structural considerations for hoists, changing benches etc which may have an impact on the character and historic fabric of the wider building. The access requirements and activity spaces required are more onerous than they are for accessible WCs / standard wheelchair sizes, etc.

2. Provision of drainage

It can be very difficult to find a route for a soil pipe connecting a new WC to ground drains while avoiding damage to the historic fabric and preserving the appearance of rooms below.

3. Provision of water supply

Finding a route for hot and cold-water supply pipes from the mains entry point and/or remote water heating source whilst avoiding damage to historic fabric and preserving the appearance of rooms adjacent can also be difficult.

4. Provision of ventilation

Often new toilets and bathrooms must be inserted into traditional buildings in central spaces away from the external walls of the building. Ventilation is then required in addition to that provided naturally by opening windows. Finding a non-disruptive route for a ventilation duct for powered extract or for passive ventilation systems can be difficult, particularly for passive ventilation systems where the vent duct/pipe has to rise continually to the open air without any sharp bends.

5. Maintenance of pipe work

Wherever water is contained in a system of pipes under pressure there is a danger of leaks causing damage to the surrounding fabric. This is particularly acute in older buildings where much of the internal fabric is timber and is therefore susceptible to rot.

3.12.4 Recommendations to meet the standard

a) Provision of toilets and bathrooms

Sanitary facilities required by the standard must be provided in a separate room or rooms. Careful consideration must be given from the earliest design proposals as to how these rooms can be fitted in so that their provision has minimal impact on historic fabric and the character of key rooms. Careful attention must be paid to:

• how the facility will be supplied with hot and cold water and where these supply pipes will run,
• how the facility will be supplied with drainage and ventilation,
• how these drainage and ventilation pipes/ducts are to be threaded through the existing structure, and
• how an accessible toilet or changing places toilet can be accessed directly from a public space.

In multi-storey projects, where possible, sanitary facilities should be stacked one above the other so that drainage and water supply pipes can be run through the new facilities with minimum effect on the rest of the building.

Generally, the sanitary facilities required by the standards should be located within a building’s smaller spaces. Where a space big enough to accommodate both bathing and toilet facilities is not available, a bathroom without water closet can be provided in one small space and a toilet with washbasin provided in another small space.

Often, existing storage cupboards can be adapted for new sanitary facilities with little impact on the character of an historic interior. In other buildings the smaller, more functional rooms of lesser interest should be used. Inserting a bathroom box into the corner of a principal room or room of historic significance should be avoided wherever possible.

b) Provision of drainage

The largest pipes, usually those serving WCs, are the most difficult to thread through the historic fabric without causing damage. Where it is found to be impossible to find an acceptable route for a soil and vent pipe, a macerator and pressure pumped system should be considered. Outlet pipes from these systems may have a smaller diameter and, being pumped, can rise as well as fall. However, the introduction of exposed pipes or ducts on internal surfaces needs to be carefully considered, especially if they must be routed over and around historic details, such as cornices.

Waterless closets may provide an alternative in cases where there are no practical or reasonably affordable means of installing a piped connection to the public sewer or the works will have a significant impact on a building’s historic fabric or character. However, practitioners should ensure they have a full understanding of the limitations of such systems, particularly regarding the reservations of users in operating them.

c) Provision of Water Supply

Water supply pipes are generally much easier to thread through the historic fabric due to their small diameter and flexible nature when using modern materials. However, care must be taken to ensure that all supply pipes are adequately supported and will not be damaged by any movement in the structure.

Hot water supply pipes should be insulated between heat source and point of delivery. This can increase the overall diameter to three or four times the diameter of the pipe itself and can exacerbate the difficulties of finding acceptable routes through the historic fabric. Where this proves to be too difficult, point of use water heaters can be used. These require only a single, small-diameter cold supply and, usually, electric power via a twin and earth cable and they benefit from reduced pipework losses compared with central hot water systems.

A modern water supply system is usually mains fed or routed from a cold-water storage tank with booster pumps to adequately pressurise the water. This is preferable to conventional systems of the past where water was gravity-fed from a tank. Difficulties occasionally arose in traditional buildings due to space not being available for the tank or because the historic structure was not adequate to bear the weight of the tank and the water within it. Where possible, it is recommended that water supply requirements are taken directly from the mains for domestic buildings, with the required pressure within the building being provided by pressure from the mains.

Storage of large quantities of water at high level should be avoided in buildings of greater cultural significance or which contain significant collections such as internal flooding from tank failure or an uncontrolled overflow can lead to considerable damage. In other cases, a tank installed in a basement, store or other low-level space should be provided with an electric pressure-pump to lift water to the required point of delivery. Where possible the load of tank and water should be transferred directly to the ground, avoiding any stress in the historic fabric.

d) Provision of Ventilation

Refer to Standard 3.14 for recommended ventilation provision to sanitary accommodation. Standard 3.14 recommends that a bathroom or a shower room is ventilated by a mechanical extract system. A passive stack system is an alternative option for designers if it can be installed sensitively into historic fabric and in accordance with BRE information paper 13/94. Passive systems may be incorporated in existing routes through the building and are best suited for dwellings with a maximum height of four storeys.

A toilet may be ventilated by a ventilator with an opening area of at least 1/30^th of the floor area of the space; typically, by background ventilation in a window or by mechanical ventilation. A single WC with no shower or bath does not require a window, only background ventilation and a form of mechanical extraction. Most domestic mechanical and passive ventilation systems require ducts of minimum 100mm diameter for circular ductwork or 200mm x 60mm for rectangular ductwork which may be easier to find routes for in traditional buildings.

3.12.5 Further reading

Consultation with the Scottish Accessible Homes Standard should be undertaken for all spaces, with particular attention to the minimum space standards required to support accessibility and future adaptation. Section 14 of the standard is especially relevant to sanitary accommodation and may require increased room sizes, specific layouts to accommodate fixtures (such as WCs, basins, and showers), and clear transfer spaces, particularly in the conversion of traditional buildings where spatial constraints maybe more pronounced.