Principles of enclosure
‘Enclosure’ is the term given to any part of a building that physically separates the external from the interior environment. It is often referred to as the ‘building envelope’, although ‘enclosure’ is considered the more precise term.
Human physiology is capable of tolerating only a narrow range of environmental conditions. Beyond this range, health and wellbeing are compromised. Through the materialisation of volumes, architecture is able to create enclosed spaces in the form of structures. A building consists of a collection of spaces bounded by separators of the interior environment, and separators of the exterior environment (the enclosure).
Where exactly the enclosure begins and the exterior environment stops can sometimes be unclear, such as in the case of ‘buffer spaces’ such as garages, screened porches, attics or vented crawlspaces.
The physical components of the building enclosure include:
- The roof system.
- The above-grade wall system (including windows and doors).
- The below-grade wall system.
- The base floor system.
The principles of building enclosure were defined by the building scientist Neil Hucheon in 1963:
- Strength and rigidity.
- Control of heat flow.
- Control of air flow.
- Control of water vapour flow.
- Control of liquid water movement.
- Stability and durability of materials.
- Fire.
- Aesthetic considerations.
- Cost.
In addition to Hutcheon’s principles, there are also considerations relating to the natural phenomena occurring in the external world, and the functions required. Some of the environmental phenomena, or ‘loadings’, that can impact on enclosure include:
- Gravity (i.e. structural loads).
- Climate and weather.
- Seismic forces.
- Noise and vibration.
- Soil type.
- Topography.
- Organic agents (i.e. aerobic life forms such as insects and mould).
- Inorganic agents (i.e. natural and artificial substances such as radon and methane).
The general functions of the building enclosure may be divided into four areas:
- Support: To support, resist and transfer all structural forms of loading imposed by the interior and exterior environments.
- Control: To control, air transfer, heat, sound, access and security, privacy, the provision of views and daylight, and so on.
- Finish: To finish the enclosure surfaces in terms of visual, aesthetic, durability, and so on.
- Distribute: To distribute services or utilities such as electricity, communications, water, and so on.
Generally, enclosures are either monolithic or composite assemblies. Monolithic enclosures involve a single material acting as the structure, the cladding and interior finish, such as load-bearing masonry. In composite assemblies, separate materials or combinations are assigned critical control functions, such as control of heat transfer or air leakage.
In general terms, enclosure types include can be categorised as the following:
- Compact or distributed.
- High rise or low rise.
- Permeable or impermeable.
- Transparent or opaque.
- Passive or active.
- Massive or lightweight.
- Temporary or permanent.
- Single or multiple units.
- Hybrids: Combinations of the above.
NB Urban Design Guidelines for Victoria, published by the State of Victoria (Australia) in 2016, defines enclosure (or 'sense of enclosure') as: ‘Where the building frontage height, street width and street tree canopy creates a feeling of a contained space within the street.’
[edit] Related articles on Designing Buildings Wiki
- Airtight.
- Building design.
- Building pathology.
- Building technology.
- Concept architectural design.
- Fabric structures.
- Structure definition.
- The building as climate modifier.
- The development of structural membranes.
- The history of fabric structures.
- Weathertight.
[edit] External references
- Building Science - The building enclosure revised.
- Canadian Architect - Principles of enclosure.
Featured articles and news
CIAT responds to the updated National Planning Policy Framework
With key changes in the revised NPPF outlined.
Councils and communities highlighted for delivery of common-sense housing in planning overhaul
As government follows up with mandatory housing targets.
CIOB photographic competition final images revealed
Art of Building produces stunning images for another year.
HSE prosecutes company for putting workers at risk
Roofing company fined and its director sentenced.
Strategic restructure to transform industry competence
EBSSA becomes part of a new industry competence structure.
Major overhaul of planning committees proposed by government
Planning decisions set to be fast-tracked to tackle the housing crisis.
Industry Competence Steering Group restructure
ICSG transitions to the Industry Competence Committee (ICC) under the Building Safety Regulator (BSR).
Principal Contractor Competency Certification Scheme
CIOB PCCCS competence framework for Principal Contractors.
The CIAT Principal Designer register
Issues explained via a series of FAQs.
Conservation in the age of the fourth (digital) industrial revolution.
Shaping the future of heritage
Embracing the evolution of economic thinking.
Ministers to unleash biggest building boom in half a century
50 major infrastructure projects, 5 billion for housing and 1.5 million homes.
RIBA Principal Designer Practice Note published
With key descriptions, best practice examples and FAQs, with supporting template resources.
Electrical businesses brace for project delays in 2025
BEB survey reveals over half worried about impact of delays.
Accelerating the remediation of buildings with unsafe cladding in England
The government publishes its Remediation Acceleration Plan.
Airtightness in raised access plenum floors
New testing guidance from BSRIA out now.