Duplex
In the UK, the term ‘duplex’ refers to an apartment (not a house) that includes two floors of accommodation, joined by an internal staircase.
Historically, this would have been referred to as a maisonette, but the term duplex has become increasingly popular because of its perceived Americanism, and is generally applied to apartments with a more modern design, whereas a maisonette might be more traditional.
An apartment with three floors can be referred to as a triplex. There is some dispute about whether an apartment with a mezzanine level should be referred to as a duplex. Where a duplex is on the top floor of a high-rise building, it might also be referred to as a penthouse.
Strangely however, and rather confusingly, in the USA, a ‘duplex’ is a dwelling comprising two apartments with separate entrances, whether the apartments are side by side, or one above the other.
[edit] Find out more
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Welsh retrofit workforce assessment
Welsh Government report confirms Wales faces major electrical skills shortage, warns ECA.
A now architectural practice looks back at its concept project for a sustainable oceanic settlement 25 years on.
Copyright and Artificial Intelligence
Government report and back track on copyright opt out for AI training but no clear preferred alternative as yet.
Embedding AI tools into architectural education
Beyond the render: LMU share how student led research is shaping the future of visualisation workflows.
Why document control still fails UK construction projects
A Chartered Quantity Surveyor explains what needs to change and how.
Inspiration for a new 2026 wave of Irish construction professionals.
New planning reforms and Warm Homes Bill
Take centre stage at UK Construction Week London.
A brief run down of changes intentions from April in an onwards.
Reslating an ancient water mill
A rare opportunity to record, study and repair early vernacular roofs.
CIOB Apprentice of the Year 2025/26
Construction apprentice from Lincoln Mia Owen wins this years title.
Insulation solutions with less waste for a circular economy
Rob Firman, Technical and Specification Manager, Polyfoam XPS explains.
Recycled waste plastic in construction
Hierarchy, prevention to disposal, plastic types and approaches.
UK Net Zero Carbon Buildings Standard V1 published
Free-to-access technical standard to enable robust proof of a decarbonising built environment.
Prostate Cancer Awareness Month
Why talking about prostate cancer matters in construction.
The Architectural Technology podcast: Where it's AT
Catch up for free, subscribe and share with your network.
The Association of Consultant Architects recap
A reintroduction and recap of ACA President; Patrick Inglis' Autumn update.
The Home Energy Model and its wrappers
From SAP to HEM, EPC for MEES and FHS assessment wrappers.
Future Homes Standard Essentials launched
Future Homes Hub launches new campaign to help sector prepare for the implementation of new building standards.
Building Safety recap February, 2026
Our regular run-down of key building safety related events of the month.
Comments
So what would the american term for duplex with two accomodations in the same dwelling be called in the UK?