Publication - Advice and guidance

Building Standards technical handbook 2017: domestic buildings

The Building Standards technical handbooks provide guidance on achieving the standards set in the Building (Scotland) Regulations 2004 and are available in two volumes, domestic buildings and non-domestic buildings. This publication is available in html and also in PDF format (in 'supporting documents' ).

Building Standards technical handbook 2017: domestic buildings
1. Structure

1.1 Structure

Mandatory Standard

Standard 1.1

Every building must be designed and constructed in such a way that the loadings that are liable to act on it, taking into account the nature of the ground, will not lead to:

  1. the collapse of the whole or part of the building

  2. deformations which would make the building unfit for its intended use, unsafe, or cause damage to other parts of the building or to fittings or to installed equipment, or

  3. impairment of the stability of any part of another building.

1.1.0 Introduction

The loadings on the building will comprise actions that may be applied both separately and in various combinations.

The stability of a building and other existing buildings in the vicinity can be affected by ground conditions which should be investigated and assessed to ensure that the ground can safely support the building.

The collapse of the whole or part of a building is clearly a matter of the highest importance with respect to public safety. The design and construction of buildings should take into account all contributing factors such as loadings, climatic conditions, partial safety factors for materials and loadings, and design methodology to ensure that there is an acceptable probability that the building will not collapse (ultimate limit state) during its design lifetime.

Similarly deformations of buildings while not leading to an ultimate collapse can lead to public safety concerns particularly where they become unfit or unsafe for use. This can become apparent in several ways ranging from cracking, movement or springiness of floors, doors or windows not opening or closing, damage to pipes and other services within the building. The design and construction of a building should ensure that, by taking into account the factors set out above, the building does not fail in normal use (serviceability limit state).

The stability of existing buildings can be affected if the design and construction of a new building does not take into account any potential impacts on existing buildings. This could lead to a risk of collapse or damage to existing buildings with a consequent risk to public safety.

Conversions - in the case of conversions, as specified in regulation 4, the building as converted shall meet the requirements of this standard in so far as is reasonably practicable, and in no case be worse than before the conversion (regulation 12, schedule 6).

1.1.1 General

In order to be safe, a building should be capable of resisting all loads acting on it as a result of its intended use and geographical location. To achieve this, the structure of a building should be designed with margins of safety to ensure that the mandatory functional standard has been met.

In clause (b) of Standard 1.1 deformations are not intended to cover aesthetic damage such as shrinkage and other minor cracking.

Specialist advice from approved certifiers of design, chartered engineers or other appropriately qualified persons should be sought if the designer is in any doubt about the loads acting on a building or how these loads can be accommodated by the structure and safely transmitted to the ground.

Fixings - the SCOSS committee has expressed concern that safety critical fixings do not always receive the attention that they deserve. Fixings are important structural components. Designers must be satisfied that fixings receive the same consideration as other aspects of the design in terms of their selection, design, installation, inspection and testing. A SCOSS ALERT “The Selection and Installation of Construction Fixings” has been issued and can be found on the SCOSS website http://www.cross-structural-safety.org.

Stone Masonry - the Scottish Stone Liaison Group publication ‘natural stone masonry in modern Scottish construction’ provides guidance in the use of natural stone in new construction. Guidance includes information on stone and mortar selection, soiling of facades and design details for structures and moisture control http://www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards.

1.1.2 Loading

Any reference to European Standards for Structure (Structural Eurocodes) in this section must be taken to include reference to the relevant UK National Annex.

The loadings to which a building will be subjected should be calculated in accordance with the appropriate Structural Eurocodes:

  1. for densities, self-weight and imposed loadings, BS EN 1991-1-1: 2002 (Eurocode 1)

  2. for snow loadings, BS EN 1991-1-3:2003 (Eurocode 1)

  3. for wind loadings, BS EN 1991-1-4:2005 (Eurocode 1)

  4. for earth retaining structures, BS EN 1997-1:2004 (Eurocode 7)

  5. any greater loadings to which the building is likely to be subjected.

1.1.3 Design and construction

Any reference to European Standards for Structure (Structural Eurocodes) in this section must be taken to include reference to the relevant UK National Annex.

The structural design and construction of a building should be carried out in accordance with the following Structural Eurocodes:

  1. for foundations, BS EN 1997-1:2004 (Eurocode 7)

  2. for structural work of reinforced, pre-stressed or plain concrete, BS EN 1992-1-1:2004 (Eurocode 2)

  3. for structural work of steel, BS EN 1993-1-1:2005 (Eurocode 3)

  4. for structural work of cold form, thin gauge steel members and sheeting BS EN 1993-1-3:2006 (Eurocode 3)

  5. for structural work of composite steel and concrete construction, BS EN 1994-1-1:2004 (Eurocode 4)

  6. for structural work of aluminium, BS EN 1999-1-1:2007 (Eurocode 9)

  7. for structural work of masonry, BS EN 1996-1-1:2005 or BS EN 1996-3:2006 Simplified calculation rules for masonry structures (Eurocode 6)

  8. for structural work of timber, BS EN 1995-1-1:2004 (Eurocode 5) or in the case of floors and roofs to domestic buildings of not more than three storeys BS 8103 Part 3 - 2009

  9. for earth retaining structures BS EN 1997-1:2004 (Eurocode 7).

The reliability of designs carried out in accordance with these codes is based on a number of assumptions set out in BS EN 1990:2002 that include:

  • the choice of the structural system and the design of the structure is made by appropriately qualified and experienced personnel

  • the design and construction is carried out by personnel having the appropriate skill and experience

  • adequate supervision and quality control is provided during execution of the work

  • the construction materials and products are used as specified in BS EN 1990 or in BS EN 1991 to BS EN 1999 or in the relevant execution standards, or reference material or product specifications

  • the structure will be adequately maintained, and

  • the structure will be used in accordance with the design assumptions.

Those responsible for procuring the design and construction of buildings based on Structural Eurocodes should be aware of these assumptions and should ensure that they have employed individuals with the necessary qualifications, skills and experience and that appropriate procedures for checking designs have been adopted.

1.1.4 Nature of the ground

The foundations of buildings should be designed to sustain and transmit the loadings to the ground in such a manner that there will be no ground movement which will impair the stability of the building. All aspects of the nature of the ground should be taken into consideration including ground movement caused by:

  • swelling, shrinkage or freezing of the subsoil, or

  • landslip, or

  • subsidence such as that arising from the collapse of abandoned mineral workings or quarrying operations.

There may be known or recorded conditions of ground instability, such as that arising from landslides, disused mines or unstable strata which, if ignored, could have an adverse effect on a building. Such conditions should be taken into account in the design and construction of the building and its foundations.

Attention is drawn to Planning Policy Guidance Note 14 (PPG 14) Development on unstable land. Although PPG 14 contains specific reference to England & Wales, it does set out the broad planning and technical issues relating to development on unstable land.

Information on the scale and nature of problems arising from mining instability, natural underground cavities and adverse foundation conditions is available from the following:

Information can also be obtained from local authorities that hold Building Standards Registers and other relevant records.

Where new foundations are to be constructed or existing foundations altered it will generally be necessary to undertake a geotechnical investigation of the site. This should be carried out using the methods described in BS EN 1997-2: 2007.

1.1.5 Stability of existing buildings

The stability of existing buildings may be affected by a new building located in their vicinity. Care must be taken to avoid undermining the foundations or otherwise affect the stability of existing buildings. The design of foundations adjacent to existing buildings should be carried out in accordance with the recommendations of BS EN 1997-1:2004.

Factors that can also affect the stability of an existing building and should be taken into account include:

  • additional or new loads arising from the construction of the new building

  • increased or new wind loads arising from the construction of the new building

  • pressure bulb extending below existing building

  • changes in groundwater level

  • loss of fines during pumping operations or climatic conditions.