- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 07 Nov 2020
A threshold is a strip of wood, stone metal and so on that forms the bottom of a doorway, which is crossed when in entering a building or a room. It is sometimes referred to as a door sill or door saddle.
Thresholds can pose a barrier to passage for people with disabilities, and so thresholds are now typically level, rather than stepped, with a level or ramped approach. However, this can create difficulties preventing water penetration or air infiltration through a doorway from the outside, and so modern threshold designs can be complex.
An ‘accessible threshold’ is defined as a threshold that is level or, if it is raised, has a total height of not more than 15mm, a minimum number of upstands and slopes and with any upstands higher than 5mm chamfered.
The word threshold can also refer to a level at which a change applies, for example; the payroll threshold above which the apprenticeship levy applies, a size of project above which an Environmental Impact Assessment might be required, the threshold for appointment of principal contractors and principal designers, the temperature threshold above which overheating might occur and so on.
 Related articles on Designing Buildings Wiki
Featured articles and news
Study examines how adjustable arrangements can succeed.
Government announces plans to improve accessibility.
Resource addresses pandemic-related NEC4 contract issues.
Incorporating EDI into the provision of fair access.
Government announces global innovation strategy.
An architectural biography. Book review.
The house where the future king of France lived.
The teacher, architectural technologist and mum offers her insights.
Careful planning needed as supply chain issues continue.
The sensitive conversion of a neglected Cornwall structure.
Plan stresses local involvement in city, town and village development.
Environment Agency publishes BAT guidance.