Scottish Building Regulations


Scottish Building Regulations

The Scottish Building Regulations provide a large range of standards and guidelines as an industry standard for everyone to follow. These can be given as recommendations such as ventilation in a dwelling or may be mandatory minimum or maximum specifications that must be followed such as fire safety precautions. The documents are linked together as the purpose of the guidance documents is to provide practical guidance on how to comply with the Scottish Building Regulations. The handbooks are not statutory instruments and therefore, are not enforceable by law on their own, however, the building regulations are statutory instruments made through the Building Scotland Act.

When followed correctly the documents are to help secure the convenience of people in and around the building as well as others who may be affected by the building or construction process. The documents also aim for minimal environmental impact by conserving fuel and power in construction in addition to achieving a more sustainable building.

Handbook Layout

The guidance documents are to act as a practical how to guide on how to best comply with the building regulations. The handbooks are in two sets, one covering domestic buildings and the other nondomestic buildings. Both sets are structured in the same way through sections and sub-sections; we will only be using the domestic handbook for our graded unit. The sections are set out as follows:

  • Section 0 General ( how to apply regulations)
  • Section 1 Structure (this section provides guidance on structural stability of
  • structural elements)
  • Section 2 Fire (containment, escape, firefighting equipment, etc)
  • Section 3 Environment (ground preparation, ground water, drainage, heating
  • lighting, air conditioning, etc)
  • Section 4 Safety (access to and within buildings, stairs, electrical safety,
  • protection from accidents)
  • Section 5 Noise (resisting sound transmission to dwellings)
  • Section 6 Energy (insulation standards, mechanical ventilation, air conditioning, lighting, etc)
  • Section 7 Sustainability (Sustainable use of natural resources)

Conversion Regulations

Section 0.12.2, schedule 6 states requirements for every conversion, to which these regulations apply, shall meet the requirements of the following standards in schedule 5:

  1. Standards 2.1, 2.3, 2.5, 2.9, 2.10, 2.11, 2.13, 2.14, 2.15 in Section 2, Fire
  2. Standards 3.5, 3.6, 3.7, 3.8, 3.9, 3.11, 3.12, 3.13, 3.14, 3.17, 3.18, 3.20, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27 in Section 3, Environment
  3. Standards 4.5, 4.6, 4.7, 4.9, 4.11, 4.12, 4.13 in Section 4, Safety
  4. Standards 5.1 and 5.2 in Section 5, Noise and
  5. Standards 6.7, 6.8, 6.10 in Section 6, Energy.

Section 0.12.2, schedule 6 outlines the standards that are reasonable practicable for conversions; every conversion, to which these regulations apply, shall meet the requirements of the following standards in schedule 5 in so far as is reasonably practicable, and in no case be worse than before the conversion:

  1. the standards in Section 1, Structure
  2. Standards 2.2, 2.4, 2.6, 2.7, 2.8, 2.12 in Section 2, Fire
  3. Standards 3.1, 3.2, 3.3, 3.4, 3.10, 3.15, 3.16, 3.19 in Section 3, Environment
  4. Standards 4.1, 4.2, 4.3, 4.4, 4.8, 4.10 in Section 4, Safety and
  5. Standards 6.2, 6.3, 6.4, 6.5, 6.6 in Section 6, Energy.

It should also be noted that standard 7.1 (Sustainability) does not apply to conversions.

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).

Ventilation

Standard 3.14; Introduction to Ventilation

Every building must be designed and constructed in such a way that ventilation is provided so that the air quality inside the building is not a threat to the building or the health of the occupants.

Recommendations for trickle ventilation in the table below are made on the basis that infiltrating air rates of 5 to 10m3/h/m2@ 50 Pa will be achieved as a matter of course in modern dwellings. However where the designer intends to use low fabric infiltration air rates of less than 5m3/h/m2@ 50 Pa in the SAP calculations (see Section 6 Energy) the areas of trickle ventilation shown may not suffice to maintain air quality and therefore an alternative ventilation solution should be adopted.

A dwelling should have provision for ventilation by either:

  1. natural means or
  2. mechanical means or
  3. a combination of natural and mechanical means (mixed-mode).

For the purposes of the design in my graded unit, option C will be used in order to ensure optimal ventilation to meet the minimum requirements outlined in the regulations.

3.14.2 Ventilation of dwellings

All buildings leak air to a greater or lesser extent. However the movement of uncontrolled infiltrating air through the fabric of a building can cause draughts and can have a significant adverse effect on the energy efficiency of the building as a whole. By improving building techniques it is possible to reduce this infiltrating air to lower levels that can improve energy efficiency (see Section 6 Energy).

Some building techniques may have little effect on air leakage and so allow the uncontrolled infiltrating air to be taken into account in the building’s ventilation provision. By building with techniques designed to reduce air leakage there will need to be a reciprocal increase in the designed ventilation provision to make up for the lower levels of infiltrating air.

Recommendations for trickle ventilation in the table below are made on the basis that infiltrating air rates of 5 to 10m3 /h/m2@ 50 Pa will be achieved as a matter of course in modern dwellings. However where the designer intends to use low fabric infiltration air rates of less than 5m3 /h/m2@ 50 Pa in the SAP calculations (see Section 6 Energy) the areas of trickle ventilation shown may not suffice to maintain air quality and therefore an alternative ventilation solution should be adopted (see clause 3.14.10).

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).

Table 3.5 Recommended ventilation of a dwelling

Work on existing buildings – where infiltration rates in a dwelling exceed 10m3 /h/m2 @ 50 Pa, which may often be the case in existing buildings, the size of trickle ventilation may be reduced to 8000mm2 for apartments and 4000mm2 for all other rooms. Alternatively, the overall provision of trickle ventilation in a dwelling may be provided at an average of 6000mm2 per room, with a minimum provision of 4000mm2 in each apartment.

Stairs

Standard 4.3

Every building must be designed and constructed in such a way that every level can be reached safely by stairs or ramps.

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).

The geometry of a stair flight can have a significant effect on the ability of people to use a stair safely and conveniently and limits should be placed on the rise and going of a stair, and steepness of pitch. The pitch of a private stair flight may be steeper than that of a public flight (any other stair) in recognition that users, as occupants, will be more familiar with the stair through frequent use. To provide safe and convenient access, the rise, going, tread and pitch of a flight in a stair should be in accordance with the following table:

With reference to 0.12.2 Schedule 6: standard 4.3 should be carried out to a degree which is reasonable practicable.

Additional information:

  1. All rises in a flight should be of uniform height.
  2. In a straight flight, or in a part of a flight that is straight, measurement should be uniform along the centreline of the flight.
  3. Where a flight consists partly of straight and partly of tapered treads, the going of the tapered treads should be uniform and should not be less than the going of the straight treads.
  4. The going measured at the narrow end of a tapered tread should be at least 50mm (see diagram to clause 4.3.1).
  5. The aggregate of the going and twice the rise should be at least 550mm and not more than 700mm. For example, stairs provided with the minimum going of 250mm would result in rises of at least 150mm.
  6. The maximum rise and minimum going on a private stair should not be used together as this will result in a pitch greater than the recommended maximum.
  7. Clause 4.2.10 should be referred to for exceptions where a private stair should meet the above recommendations for ‘any other stair’.

The most comfortable combination of rise and going varies between individuals but in general, a going in excess of the minimum, resulting in a figure in the upper end of the range in note 5 above, will increase both safety and amenity.

U-Values

In the case of a building that was previously designed to be heated, the impact on energy efficiency as a result of the conversion, may be either negligible, none whatsoever or in some circumstances even an improvement. A less demanding approach than identified in clause 6.2.6 is recommended which at the same time still ensures that some overall improvements are being made to the existing building stock. Where an extension or conservatory is formed and/or alterations are being made to the building fabric at the same time as the conversion, the guidance given in clauses 6.2.9 to 6.2.12 should also be followed.

With reference to 0.12.2 Schedule 6: standard 6.2 should be carried out to a degree which is reasonable practicable.

U-values – Clause 6.2.7 states the where conversion of a heated building is to be carried out; the existing insulation envelope should be examined and upgraded following the table below:

Additional information:

  1. Where upgrading work is necessary to achieve the recommended U-values, reference should be made to ‘Reconstruction of elements’ in clause 6.2.11 and more demanding
  2. U-values achieved, where reasonably practicable.
  3. Excluding separating walls and separating floors between heated areas where thermal transmittance need not be assessed, provided measures to limit heat loss arising from air movement within a cavity separating wall are made (see clause 6.2.1).
  4. The total area of windows, doors and roof lights, should not exceed 25% of the floor area of the dwelling created by conversion. Alternatively, a compensatory approach should be taken.
  5. Windows with a window Energy rating of Band C or better may also be used (www.bfrc.org) http://www.bfrc.org/.

Daylighting

The purpose of this standard is primarily to ensure that an adequate standard of day lighting is attained in habitable rooms in dwellings to allow domestic activities to be carried out conveniently and safely. A kitchen or toilet is not deemed to be a habitable room in terms of the building regulations.

Conversions – in the case of conversions, as specified in regulation 4, the building as converted must be improved to as close to the requirement of that standard as is reasonably practicable, and in no case worse than before the conversion (regulation 12, schedule 6).

Standard 3.16.1 states that every apartment should have a translucent glazed opening, or openings, of an aggregate glazed area equal to at least 1/15th of the floor area of the apartment and located in an external wall or roof or in a wall between the apartment and a conservatory.

Standard 3.16.1 states that an extension however constructed over a glazed opening to a room, because of its greater solidity, can seriously restrict daylight from entering the dwelling and the existing room and extension should be treated a single room.

The area of the translucent glazed opening to the extension should be at least 1/15th of the combined floor area of the existing room and the extension. A new translucent glazed opening should be provided to the existing room but, where this is not practicable, the wall separating the 2 rooms should be opened up to provide a single space.

To ensure sufficient ‘borrowed light’ is provided, the opening area between the existing room and the extension should be not less than 1/10th of the total combined area of the existing room and the extension. Clause 3.14.7, covering ventilation, also recommends that the existing room and extension are treated as a single space.

Activity Spaces

Every apartment should be of a size that will accommodate at least a bed, a wardrobe and a chest of drawers, this being the minimum furniture provision that may be expected in such a room. Associated activity spaces for each item of furniture should be shown as in the diagram below. A door swing may open across an activity space.

Conversions – for clause 3.11.1 regarding Apartments in the case of conversions, as specified in regulation 4, the building as converted must be improved to as close to the requirement of that standard as is reasonably practicable, and in no case worse than before the conversion (regulation 12, schedule 6).

Additional information:

  1. Activity spaces for furniture may overlap.
  2. A built-in wardrobe space of equal size may be provided as an option to a wardrobe.

Bibliography:

http://www.gov.scot/Resource. (2013) Technical Handbook – Domestic,

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