Loft bathroom planning guide

Construction and glazing ideas to ensure your space is structurally sound, bright and practical

By Paula Woods | 1 April 2021

Building a loft bathroom is a great use of space beneath the roof. But there are important structural and practical issues to consider in the planning stages. All work will need to comply with Building Regulations, including installing an extractor fan to remove moisture from the room.

White tiled loft bathroom with sloping ceiling, walk-in shower, basin and loo

A Victorian terrace dormer conversion by Studio 30 Architects

Is there headroom for a loft bathroom?

Most roofs with a ridge height of at least 2.2m are suitable for conversion. Pre-1960s homes tend to have a steep roof pitch. More modern trussed roofs may require structural alterations. Roof windows are an economical glazing solution but a dormer increases headroom.

Chris Dyson Architects

Remodelled 1960s home by Chris Dyson Architects. Bathroom design Edwina Boase

Raise the roof

Add a dormer or mansard with a sloping profile and flat roof to increase the amount of usable floor space and provide a view of the surroundings. This also creates some flexibility as to where to site the staircase. Homes with a hipped roof can include an upright gable end to provide more space.

Loft bathroom with angular window following the roofline

Dormer conversion in a Victorian mid-terrace home by Urbanist Architecture

Make structural alterations

If you need to make complex structural alterations to the roof, this will require the services of a structural engineer. Floor joists may require strengthening to bear the weight of heavy bathroom fixtures and fittings. Seek advice from a RIBA architect or try The Institution of Structural Engineers.