Dimensions
Every Room Must be Fit for Purpose-Part C
The National Building Regulations (NBR) are not prescriptive when it comes to the dimensions or size of rooms and buildings. However it is vital that the size of any room or space is fit for the purpose for which it was intended.
In the case of a really small house – or “dwelling unit” – the floor area of the entire building must be able to accommodate a “habitable” room as well as a separate room with toilet facilities. This is more for sanitary reasons than for comfort, and it makes perfect sense.
That’s about it, though the SANS deemed-to-satisfy requirements do give a little more guidance.
The updated requirements, published by the SABS in October 2010, were compiled with the assistance of the South African Institution of Civil Engineering. You can buy them from the SABS, either from one of their offices, or online.
What SANS 10400-C Covers
In essence the section on Part C, Dimensions in the Code of practice for the application of the National Building Regulations simply establishes the requirements for plan size dimensions as well as room heights and overall floor areas. It’s that simple.
Definitions
The National Building Regulations and Standards Act has a glossary of terms; however there are additional terms that are defined in the various parts of the SABS codes of practice. In Part C, there is a new definition of category 1 buildings. These are specifically buildings that are classified as:
- Places of instruction (A3)
- Buildings used for worship (A4)
- Small shops (F2)
- Offices, as well as banks, consulting rooms and similar (G1)
- Dormitories where a groups of people are accommodated in one room (H2)
- Domestic residences with two or more dwelling units on a single plot (H3)
- Dwelling houses, which may or may not include a garage and/or outbuildings (H4)
But in addition to the classification there are several other parameters:
- There must not be a basement in the building
- The maximum length between walls or “members” that provide lateral support is 6 m
- The floor area in the building may not exceed 80 square metres.
There are certain requirements and limitations that are imposed on category 1 buildings by other parts of SANS 10400. For instance, in terms of Part T, Fire Protection, they are restricted to one storey. The maximum number of people allowed in category 1 buildings is also regulated.
Supposedly this means that if a house, church, office, shop etc has a basement or is double storey, it is not classified category 1, and a different code of practice will apply.
Dimensions of Plans
When you see dimensions on plans, you will know that these are the horizontal dimensions between UNPLASTERED wall surfaces. Of course once you plaster a wall and re-measure it, the distance between the two walls will be slightly less, since there will usually be at least 10 mm of plaster on the wall (though no one coat should be thicker than 15 mm) – and up to 30 mm if three coats of 10 mm-thick plaster are applied.
The Height of Rooms
If you’re a keen camper, you may not mind bending down in your temporary canvas home. But homes and other buildings have to be able to accommodate people standing up! Very few people are taller than 1,8 m (most are shorter), and so room heights generally are set at between 2,1 m and 2,4 m. This doesn’t, however, prevent designers making ceilings higher than this, even though it does increase building costs.
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 stand upright. |
| 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 dimension 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 Areas for Buildings
Having said that the floor area of a small size home must be large enough to be habitable, plus must accommodate a separate toilet, there are other specifications in the regulations to consider. So while the minimum specifications are pretty tiny, they are not quite as small as you might be imagining.
For instance the regulations state that the floor of any permanent building that is used as a “dwelling house” must be no less than 30 m². Permanent category 1 building may be smaller, 27 m²; and temporary buildings can be as small as 15 m². So while a bedroom can legally be as small as 6 m² (providing no wall is shorter than 2 m) it won’t be sufficient to add on a bathroom and loo and claim that it is a house!
There are also minimum specifications in terms of the floor area allowed for a certain number of people using a room or building at any one time. This is based on the dimensions shown on the plans, but excluding the area that is taken by built-in cupboards, cabinets and so on (see drawings below).
These references are specifically in terms of change rooms and dining rooms, and so relate not only to private dwellings, but to hostels and other establishments. If one to 15 people are going to be using a dining room, the minimum allowable area is 0,8 m² per person, but the room must still be at least 6 m² in size.
Not much space to party!
Main Photograph top © Janek Szymanowski
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https://sans10400.org.za/public-safety/
Your client? Surely if you build for someone else you know what they want you to build? And then he/she would also have approved the plans prior to them being submitted to council for approval. Or am I missing something? If your plans have been approved, I have to assume that they comply with NBR otherwise they wouldn’t have been approved.
The regulations (Part C) say that the minimum plan area for any habitable room other than a kitchen, scullery or laundry (and this applies to ALL occupancies) is “6 m2 with no linear dimension less than 2 m”.
Floor area of any “dwelling house” may not be less that 30 m2 in the case of any permanent building other than Category 1 building which must be at least 27 m2 in size.
Part A, General principles and requirements, gives a table of different classes of occupancy. I assume this will be either H2 Dormitory Occupancy where groups of people are accommodated in one room.
H3 Domestic residence Occupancy consisting of two or more dwelling units on a single site.
H4 Dwelling house Occupancy consisting of a dwelling unit on its own site, including a garage and other domestic outbuildings, if any.
Part A also specifies maximum “design population” for rooms. i.e. It can’t be smaller than this.
H2 = 1 person per 5 sq m
H3 and H4 = “2 persons per bedroom” … obviously this is read with the 30 or 27 sq m minimum for the house, and min 6 sq m for any habitable room. While not ideal by any means, you could fit a double bed into the min size – (if the room was square) with 1 m x 3 m along one side – and 800 mm on either side of the bed! So legally the rooms you have built are not “too small”.
But then in Part P, Drainage, there are additional regulations that relate to the provision of sanitary fixtures. There are exceptions for shops in terms of these not needing to be in the same building, but I am not sure about exemptions for H2, H3 and H4.
H2 depends on the number of people using the dormitories. H3 and H4 must have at least 1 toilet, 1 bath or shower and one basin. But again, if you have approved plans, I don’t see the problem.
Hi Penny
Thanks for the reply. We have built accomodation (approved drawings etc). But an inspection done by our client says the room sizes are too small. The rooms are 12 square metres for 2 people.
They ablutions, entertainment, dining etc are in separate buildings.
Charmaine the minimum sizes for rooms is given in SANS 10400, Part C Dimensions, which is explained on this page. But your question is a bit strange. Are you wanting to provide temporary accommodation for laborers? If so you will have to get permission from the local authority. If you are going to accommodate a labourer in a servant’s quarter or similar on your property, the minimum size is no different to the minimum size required for you!
Hi
What is the minimum room size for accommodation?
* For one labourer
* For two labourers
Thanks
Charmaine
Lance, A concrete roof would only be defined as “living space” if the roof became a floor. i.e. If you were to use it as an elevated patio, they could include the area as “living space”. If you are concerned, give their planning department a call and double-check.
Hi there Penny
I’m planning a new build and was thinking of having a flat concrete roof. My question is would the municipality charge for that concrete roof as living space? I realize that the municipality calculates the rates based on the square meterage of a dwelling, so would the flat concrete roof be included?
Thanks for a brilliant site!
Lance
Generally a double garage will be 6.5 m wide. But the size will be on your plans. Measure what you have and compare the dimensions. You’ll soon see whether your builder scammed you!
Tiaan this information will be specified on the approved plans.
Hi, I need to know what the dimensions of the first floor should be in thickness… considering that all the rooms in the house of the ground floor are 220mm thick , and not exceeding a room area of 60m^2?
I recently purchase a 3 year old free standing house inside an Estate
in Greestone. My question is what is the standard size of a Double
garage? We are battling to park 2 cars, a small car and Suv with and
be able to walk around cars with the garage door closed. I’m sure the
buider short changed me. Branden
That’s not quite what I said. Basically plans include a description of “purpose” or function. And technically that is what the structure or room is for. Which rules have you heard are due to change? Let me know and I’ll find out. The NBR has only just been updated, and unless there are new parts, I doubt that there will be changes at this stage.
Thanks. Surely I won’t do it alone but knowing options beforehand helps alot. So a workshop, garage or hobby room would be allowed as long as you don’t live in them? I have just heard that those rules are going to change in March 2013. Do you know about that?
It varies and depends on the building line for the property. This should be indicated on the site plan for the property, and on the original drawing when the area was surveyed (which you can get from the Surveyor General’s office in Pretoria). But the local authority can give permission for a garage to be built on the boundary, though you would need to get permission from neighbours if the building line is changed. To extend or build a garage, you will need plans. All the NBR apply in terms of H4, which is a “dwelling house – occupancy consisting of a dwelling uni on its own site, including a garage and other domestic outbuildings, if any”. Plans will have to be drawn up by a “competent person” (CLICK HERE to read more about competency) who will advise what is required in terms of height, light and ventilation, fire walls etc. If the plans state that this is a garage, technically this is the only purpose it may be used for. However many garages are built either with additional space for storage, or are in fact used for storage. The two issues are “habitable rooms” and probably also rates payable to council. e.g. You cannot “live” in a garage, because it isn’t built for that purpose.
You seem competent. I see many garages built directly at boundary wall and not leaving 1.5m. Is it old rules? I would like to extend/move my existing garage to the boundary wall. Can I use it for other purposes, must the “garage” not have any windows and a maximum height or what regulations apply?
I would also be concerned that they would look straight onto your patio!
But to answer your question… It is not so much a safe distance that you need to worry about, but an assurance that their drainage will be properly designed. We have recently been inundated with messages and queries from people whose neighbors blatantly build and alter boundary walls and then take zero responsibility for damage caused when they collapse or there isn’t proper runoff. Rain water needs to be channelled by gutters and downpipes into suitable storm water drains that run off to a municipal drain – and NOT onto your property.