Dimensions – Part C Every Room Must be Fit for Purpose
Ensuring Adequate Space Allocation in Construction: Part C Specifications
The National Building Regulations (NBR) set the framework for construction guidelines in South Africa. When it comes to the dimensions and sizes of rooms and buildings, the NBR isn’t prescriptive. However, the crucial consideration remains that the size and dimensions of any space must be suitable for its intended purpose.
In the context of a compact dwelling, it’s imperative that the building’s floor area can effectively house a “habitable” room along with a separate space equipped with sanitary facilities. This requirement primarily serves sanitation purposes rather than pure comfort, embodying a logical and necessary stipulation.
Updated in October 2010 by the South African Bureau of Standards (SABS), these requirements were developed in collaboration with the South African Institution of Civil Engineering. To acquire a copy, one can obtain these standards directly from the SABS, either at their physical offices or through their online platforms.
Scope of SANS 10400-C: Dimensions
The section dedicated to Part C within the Code of Practice for the application of the National Building Regulations essentially outlines the prerequisites concerning plan sizes, room heights, and overall floor areas. Its primary aim is to establish clear guidelines for construction parameters and spatial specifications.
Defined Terms and Classification
The National Building Regulations and Standards Act presents a glossary of terms. Part C introduces the definition of category 1 buildings, encompassing various specific classifications, including places of instruction, buildings for worship, small shops, offices, dormitories, domestic residences, and more. Additionally, certain parameters restrict aspects such as the absence of a basement, limitations on lateral support length, and a maximum floor area of 80 square meters.
These category 1 buildings face specific constraints imposed by other parts of SANS 10400. For instance, in Part T, Fire Protection, these structures are constrained to a single story, and there are regulated limits on the maximum occupancy.
Understanding Building Classification
Housing structures, places of worship, offices, and shops, each of these buildings has to adhere to specific building codes. For instance, a double-story house or a building with a basement does not fall under category 1, thereby necessitating compliance with a different set of construction guidelines.
Dimensions on Plans: Interpretation
When assessing plans, the indicated dimensions refer to the horizontal measurements between UNPLASTERED wall surfaces. However, once a wall is plastered, the actual distance between these walls slightly reduces due to the added plaster thickness. Typically, plaster adds around 10mm to the wall’s width, with a maximum of 30mm for three coats of 10mm-thick plaster.
Room Height Considerations
Unlike camping tents where crouching might be acceptable, residential and commercial buildings must allow people to stand comfortably. Room heights generally range between 2.1m and 2.4m, accommodating the average person’s height, with provisions for higher ceilings, albeit at increased building costs.
The minimal room height is measured from the finished floor to the underside of the ceiling, roof covering, or any structural element larger than 30% of the room’s area. Moreover, if there’s a structural element projecting below the ceiling level, the height must not fall below 2.1m.
Minimum heights specified relate to different rooms in homes and other buildings:
|Bedrooms.||2,4 m above a floor area of at least 6 sq m with a clear|
height of at least 1,8 m at any point that is more than
0,75 m from the edge of the floor space.
|Any other habitable rooms in dwelling houses/units.||2,4 m above a minimum of 70% of the floor area, and|
not less than 2,1 m above the remaining floor area.
|All other habitable rooms.||2,4 m.|
|Passages and entrance halls.||2,1 m.|
|Bathrooms, shower rooms, laundries and toilets.||2,1 m above any area where a person would normally|
|Open mezzanine floor with an area no more than|
25% of the area of floor immediately below it
|2,1 m above and below the mezzanine floor.|
Note that this specification has not changed since 1990 – so the existing table in the free downloadable version of SANS 10400 applies.
When ascertaining the height of a room, the minimum dimensions allowed is measured from the top of the finished floor to either:
- the underside of the ceiling,
- the underside of the roof covering (if there isn’t a ceiling), or
- the underside of any structural element (member) that is below the ceiling or roof and is larger than 30% of the plan area of the room. In addition, if there is a structural element projecting below ceiling or roof covering level, the height of the projection may not be less than 2,1 m
In the top section of the drawing, two levels are indicated. Normally the height would be taken at level 2, but if the total plan size of the shaded areas in the bottom part of the drawing exceed 30% of the total area of the room, the ceiling height should be measured to the first level indicated.
Floor Area Specifications
While a small dwelling must have adequate space for habitation and a separate toilet, the regulations impose specific conditions to ensure viable living areas. Although the minimum requirements might seem modest, they are not as minimal as one might assume.
For instance, a permanent dwelling house must have a floor area of at least 30m², whereas category 1 buildings can be smaller, down to 27m² for permanent and 15m² for temporary structures. Despite the legality of a bedroom being as small as 6m², this alone wouldn’t suffice as a complete house without appropriate facilities.
Furthermore, minimum floor area specifications are determined concerning the number of occupants. Spaces like dining rooms are regulated based on the number of individuals using them, ensuring adequate space per person within the stipulated dimensions.
Compliance with the National Building Regulations, particularly Part C, ensures that spaces within buildings adhere to specific dimensions and standards. These guidelines are established to create living and working environments that are both safe and functionally adequate for their intended purpose, ensuring that buildings are fit for occupancy and use according to defined standards.
Understanding and adhering to these regulations not only guarantee the safety and comfort of inhabitants but also serve to maintain the quality and integrity of construction practices within South Africa.
Not much space to party!
Main Photograph top © Janek Szymanowski