The design includes an elongated domed copper roof that relates to the canopy of the Great Chestnut Tree and is inspired by the proximity of the river. It harbours five radiating cubicles, including one disabled person facility and a parent/baby changing room, along one side of an oval shaped building. Design principles aim to make users feel safer, by designing out any hidden corners and careful use of lighting. A broad-based team have ensured that safety has been a priority. Materials have been chosen that are easy to clean and maintain, including the self-coloured sto-render, arranged in panels of muted colours around the wall that faces onto Midsummer common. In an effort to reduce environmental impact, rainwater is harvested in a tank underground and used to flush the toilets.

Copper standing seams, although the more difficult detail to execute, were chosen as this expressed the three-dimensionality of the curved roof. This has since become the defining feature of the scheme, from which the fond nickname ‘the armadil-loo’ was coined by locals.