- 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
A challenging environment, where nothing can be left to the fate.
First report showing good product availability and prices.
Summary of the guide to the roles, duties and competencies.
The medieval stained glass of Herefordshire and Shropshire.
Environment Committee publish open letter to the Mayor.
Significant transformation for built environment landscape.
Setting new benchmarks to help reshape design practice.
Looking back at the Egan Report and its impact.
CLC launch plan to support the natural environment.
Terminology, benefits and barriers.
Electrotechnical businesses are feeling the effects of the economic slowdown.
When did they start and how many are there?
Roadmap to guide professionals in using smart technology.
Campaigning for buildings of all periods.
Meaning, understanding and implementation.
Advancing sustainable and regenerative project management.