Permanent structure
In reality no structures are truly permanent. They will degrade over time and will ultimately fall into disrepair, fall out of use or will be demolished.
However, a structure may be considered to be permanent if it is designed for a long-term use, rather than short-term or temporary use. The duration that might be considered ‘long term’ will vary depending on the design life of the structure.
BS EN 1990, Eurocode - Basis of structural design, (Eurocode 0) gives indicative design lives for various types of structure:
- Category 1: Temporary structures, not including structures or parts of structures that can be dismantled with a view to being re-used – 10 years.
- Category 2: Replaceable structural parts, e.g. gantry girders, bearings – 10 to 25 years.
- Category 3: Agricultural and similar buildings – 15 to 30 years.
- Category 4: Building structures and other common structures – 50 years.
- Category 5: Monumental building structures, bridges and other civil engineering structures – 100 years.
The actual life of a structure will vary depending on factors including:
- Materials.
- Workmanship.
- Moisture, humidity and rain.
- Wind.
- Temperature and temperature fluctuations.
- Pollution.
- Solar radiation.
- Maintenance.
- Intensity of use.
In legal terms, The Town and Country Planning (General Permitted Development) Order 1995 defines a temporary use as one that does not exceed 28 days in any calendar year. Beyond this, under normal circumstances, a structure would be considered to be ‘permanent’ and so would require planning permission. However, this is reduced to 14 days for some uses, and only certain temporary uses are permitted at all without planning permission. See Temporary use for more information.
Schedule 2 of the building regulations defines a temporary building as, ‘A building that is not intended to remain where it is erected for more than 28 days’. For more information see: Temporary structure.
During the construction process, it is normal to distinguish between permanent works and temporary works. Temporary works may also be regarded as temporary structures comprising an arrangement of elements that are necessary only during the construction process itself. These can include scaffolding, formwork, trench supports and so on.
Temporary works are defined in BS5975: 2008 + A1: 2001 Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework as ‘parts of the works that allow or enable construction of, protect, support or provide access to, the permanent works and which might or might not remain in place at the completion of the works.’
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
CIOB Construction Manager of the Year 2025
Just one of the winners at the CIOB Awards 2025.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Construction Products Reform Green Paper and Consultation
Still time to respond as consultation closes on 21 May 2025.
Resilient façade systems for smog reduction in Shanghai
A technical approach using computer simulation and analysis of solar radiation, wind patterns, and ventilation.