Sash
A sash is a glazed part of a window or door assembly that opens for purposes of ventilation, viewing out, etc.
In a casement window, the sash is the hinged part of the window (within the frame) that opens outwards or inwards for ventilation. It is the part which holds the glass in position in a secondary frame within the main window frame.
In a traditional sliding sash window, the sash is the glazed part which slides vertically to allow ventilation, views out etc, and holds the glass in place. Such windows usually have two sliding sashes.
For more information see: Window.
The term sash can also be applied to doors which incorporate glass, i.e the hinged part of a door assembly which opens for entry and exit and which is either fully or partly glazed. When a door is not glazed, the opening part is usually called the ‘door leaf’.
NB Short Guide, Fabric Improvements for Energy Efficiency in Traditional Buildings, published on 1 March 2013 by Historic Scotland, defines a window sash as: ‘The timber frame around the glass in a window. The term is used almost exclusively to refer to windows where the glazed panels are opened by sliding vertically, or horizontally hence the term sash and case window.’
[edit] Related articles on Designing Buildings
Featured articles and news
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.
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.
Planning reform: draft NPPF and industry responses.
Last chance to comment on proposed changes to the NPPF.
A Regency palace of colour and sensation. Book review.