Accessible Design for London Homes: Part M, Wet Rooms, Level Access, and Through-Floor Lifts

Building Regulations Part M (Access to and Use of Buildings) sets out requirements for accessibility in new buildings and extensions. Part M has two main parts:

Part M Volume 1 (dwellings): applies to new dwellings and extensions that create new habitable rooms. It sets out minimum access standards for the approach to the dwelling, the entrance, and the internal layout.

The three categories of dwelling under Part M Volume 1: Category 1 (Visitable): the baseline standard — the minimum access provision that must be incorporated in all new dwellings. This includes a level approach and threshold, minimum doorway widths (750mm clear opening for all principal access doorways, 650mm for other doorways), a WC accessible without going upstairs, and minimum circulation space in the entrance hall and living room. Category 2 (Accessible and Adaptable): a higher standard incorporating features that make the dwelling readily adaptable for occupants with varying mobility needs — wider doorways (800mm clear opening), a bathroom suitable for a step-in shower or level-access shower, reinforcement in bathroom walls for grab rails, and a space suitable for a through-floor lift. Category 3 (Wheelchair User Dwellings): designed to be fully wheelchair accessible — wider hallways, turning circles in all principal rooms, a full wet room bathroom, accessible kitchen heights and reach ranges, and external ramp access.

Part M and extensions: an extension to an existing dwelling does not automatically require compliance with all of Part M Volume 1. However: Where the extension creates a new entrance to the dwelling, the approach and threshold should meet the Category 1 standard. Where the extension creates a new habitable room (bedroom, study, living room) at ground floor level, the access provisions for that room should be considered. Where planning permission is required, some Local Planning Authorities impose planning conditions requiring Part M Category 2 compliance for new extensions.

In practice, the most important Part M principle for existing London Victorian terraces is the Category 1 standard — a step-free entrance and ground-floor WC provision. Many Victorian terraces have a step at the front door (typically 100–200mm) and no WC at ground floor level — common adaptation targets.

The single most impactful accessible design measure for most London homes is a ground-floor wet room or level-access shower room. It enables independent bathroom use without needing to access the upper floor, and is the foundation of a single-floor accessible living arrangement.

What is a wet room? A wet room is a bathroom where the entire floor is waterproofed and drains to a floor drain — there is no shower tray or shower enclosure. The shower area is part of the general floor, which slopes gently to the drain. A wet room is fully level-access and requires no step over a shower tray — making it the most accessible shower arrangement. It is also easy to clean, visually simple, and works well in small spaces.

What is a level-access shower (compared to a wet room)? A level-access shower has a shower tray that is at floor level (or recessed into the floor structure), with no step between the shower tray and the surrounding floor. Unlike a wet room, only the shower tray is waterproofed — the rest of the room is conventional. Level-access showers are less expensive to install than wet rooms and are a suitable compromise in existing bathrooms where full wet-room waterproofing is not practical.

Structural requirements for a wet room: the floor must be capable of supporting the weight of the wet room construction (tiles and waterproofing membrane, which are heavier than standard floor coverings) and must be capable of incorporating a floor fall to the drain without excessive slope. In a timber-framed suspended ground floor, the joists may need to be cut and headed off to form a recess for the drain and any associated fall. The structural implications must be assessed by a structural engineer or experienced builder before specifying a wet room on an upper floor or over a suspended timber ground floor.

Waterproofing: the wet room waterproofing system (tanking membrane) must be applied to all surfaces that will contact water — the floor and the lower sections of the walls, at minimum. The tanking must be compatible with the tile adhesive and grout system used on top. A BS 8000 compliant installation should be used.

Drain position and type: the floor drain should be positioned to minimise the fall needed across the floor — typically at the lowest point of the shower zone, near a wall. Linear (channel) drains are popular in accessible wet rooms as they can be positioned at the room perimeter, allowing a single even fall across the floor from one side to the other.

Grab rails and supports: wall-fixed grab rails adjacent to the shower, WC, and bath (if retained) are standard accessible bathroom requirements. Grab rails must be fixed to blocking or structure within the wall — a standard plasterboard wall cannot carry the loads from a person pulling on a grab rail. Where walls are being replastered or retiled in connection with a wet room installation, it is good practice to install continuous plywood blocking behind the plasterboard throughout the bathroom — this allows grab rails to be fixed anywhere in the room, now or in the future.

Doorways in Victorian London terraces are often narrower than modern accessibility standards require. The standard Victorian internal door opening is typically 686mm (2 foot 3 inches) or 762mm (2 foot 6 inches) clear opening — narrower than the 800mm clear opening width recommended for wheelchair access.

Part M requirements for doorway widths: Category 1 (Visitable): 750mm clear opening width for principal access doorways; 650mm for other doorways. Category 2 (Accessible and Adaptable): 800mm clear opening width for all principal access doorways.

Clear opening width: the clear opening width is the usable space when the door is open at 90 degrees — not the nominal door leaf width. A 762mm door leaf in a standard frame typically provides a clear opening of approximately 700mm (the frame takes 25–35mm from each side).

How to widen a doorway: widening a doorway in a load-bearing wall requires: Assessment of whether the wall is load-bearing (structural engineer advice). Temporary propping while the new, wider lintel is installed. Installation of a new lintel of appropriate size and bearing length to span the wider opening. Building Control notification (Part A — Structure). The blockwork or brickwork at the sides of the enlarged opening is rebuilt, the wall is re-plastered and redecorated.

Non-load-bearing partitions: widening a doorway in a non-load-bearing partition is simpler — no temporary propping or new lintel is required. The partition either side of the new door opening is rebuilt or trimmed back to the required width.

Circulation space: accessible design requires clear circulation space for a wheelchair to manoeuvre — a standard wheelchair requires a minimum turning circle of 1500mm diameter. In a Victorian terrace, achieving turning circles in all rooms is often not possible without significant structural changes — but targeted improvements (wider doorways, furniture repositioning, removal of unnecessary clutter) can significantly improve manoeuvrability.

Thresholds: level thresholds (no step between rooms or between internal and external) are a critical accessible design element. Victorian terrace front door thresholds are often raised above external ground level by 100–200mm. Options for creating a level approach include: lowering the external ground level (where possible); installing a ramp (maximum gradient 1:20 for wheelchair self-propulsion, 1:12 for assisted propulsion); or, where the internal floor level can be changed, raising the external approach. The choice depends on the specific levels and constraints of the property.

A through-floor lift (also called a platform lift or home lift) is the most effective way to provide wheelchair or mobility-impaired access to upper floors in a London Victorian terrace. Unlike a stairlift, a through-floor lift can carry a wheelchair user without the need to transfer to a seat.

How a through-floor lift works: a platform lift uses either hydraulic or electric actuation to raise a platform (large enough for a wheelchair and its occupant) vertically through a penetration in the floor between two levels. The platform typically has folding gates or doors on the upper and lower levels to prevent falling into the shaft when the platform is not at that level.

Space requirements: the minimum through-floor lift shaft size (the penetration through the floor) is typically 900mm x 1,400mm — for a platform that can accommodate a standard wheelchair and its occupant. The shaft requires a structurally sound trimmer frame around the floor penetration, and adequate headroom above the upper landing position for the platform to fully rise.

Suitable locations: through-floor lifts are typically installed in: A cupboard (converting an existing storage cupboard on both floors into the lift shaft and landings). A corner of a room (where a portion of the floor area is sacrificed on both levels). A purpose-built shaft addition to the building (usually a single-storey addition on the rear or side of the property).

Structural requirements: the floor penetration for a through-floor lift requires the existing floor joists to be cut and headed off — the cut joists transfer their loads to trimmer joists and trimmers around the opening. This is structural work requiring Building Regulations Part A compliance (structural engineer or approved contractor).

Building Regulations: a through-floor lift installation is notifiable under Building Regulations — principally Part K (protection from falling, collision, and impact), Part M (access), and Part A (structural trimming of the floor). Building Control must inspect the installation and issue a completion certificate.

Costs: Standard through-floor lift (supply and install, single stopping position to one upper floor): £8,000–£15,000. Premium through-floor lifts with enclosed shaft (more suitable for multi-storey access): £15,000–£30,000. Structural work (floor trimming, shaft construction): £1,000–£5,000 additional.

Running costs: through-floor lifts use very little electricity — typically 1–3p per journey.

Stairlifts (alternative for ambulant users): a stairlift carries the user up the staircase in a seat, fixed to a rail on the staircase. Stairlifts are much cheaper (typically £2,000–£6,000) and less structurally invasive than through-floor lifts. However, they require the user to transfer from a wheelchair at the bottom of the stairs and back to a wheelchair at the top — and therefore do not provide true wheelchair access to upper floors. For ambulant users who can manage stairs with difficulty, a stairlift is often the most appropriate and cost-effective adaptation.

The Disabled Facilities Grant (DFG) is a means-tested grant provided by the Local Authority (via the Housing Grants, Construction and Regeneration Act 1996) to fund adaptations to enable disabled people to remain in their own homes.

Who is eligible: the DFG is available to homeowners, private tenants, and housing association tenants who have a physical disability or health condition that affects their ability to use their home. The disabled person must live (or intend to live) in the property. Both the disabled person and the property are assessed.

Maximum grant amount: the maximum DFG in England is £30,000 (2024 figure). This is a means-tested grant — the amount of grant available depends on the income and savings of the applicant (and spouse or partner). Some applicants receive the full grant; others receive a partial grant and must contribute the remainder themselves.

What the DFG can fund: mandatory DFG works (which the Local Authority must fund if the applicant meets the eligibility criteria) include: Facilitating access to the dwelling and the main rooms (widening doorways, installing ramps, level thresholds). Making the dwelling safe for the disabled person and their carers. Facilitating use of a room used or usable as the principal family room. Facilitating access to and use of a bedroom, bathroom, or toilet. Facilitating preparation and cooking of food.

How to apply: the application is made to the Local Authority's housing adaptations team or housing grants team. A local authority occupational therapist (OT) typically assesses the disabled person's needs and recommends specific adaptations. The OT's recommendation is an important part of the grant application — it confirms that the proposed adaptations are necessary and appropriate for the person's specific needs.

Timescales: DFG applications can take 3–12 months from initial referral to grant approval and works commencement, depending on the Local Authority's resources. The application process involves an OT assessment, a property survey, obtaining quotes from approved contractors, and Local Authority approval of the grant.

Other funding sources: in addition to DFGs, adaptations may be part-funded by: the Better Care Fund (health and social care integrated funding); charitable grants (Foundations is the national body for home improvement agencies that can provide advice and support in accessing grants); the local Home Improvement Agency (HIA — organisations that help older and disabled homeowners make adaptations, often providing a managed service to oversee the works on behalf of the householder).