Nov 172011
 

All buildings must have a strong, serviceable,

stable and durable design-Part B

Why do you suppose we need structural design professionals to be involved in every aspect of building processes? I’ve thought about this often, since we’ve done a load of DIY projects that involve building, and we have seldom had professionals help us. But the point is that any building or structural element, however simple it may be, must be built in accordance with accepted principles of structural design. For instance we don’t just pile bricks on top of one another without sandwiching suitably mixed mortar between them – although I have visited an amazing home in Johannesburg where an architect totally defied this principle and built an incredible home on Linksfield ridge out of bricks sans mortar! But this is not the norm. Similarly, we don’t balance poles together like pick-up-sticks in the hope that they will stay in place.
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The Role of the Regulations in Structural Design

As the national building regulations state:

“Any building and any structural element or component” must be designed to “provide strength, stability, serviceability and durability”.

It is also vital that buildings are designed so that if the structural system is in any way overloaded they won’t collapse with disastrous consequences.

The regulations also state that these design requirements shall be “deemed to be satisfied” when buildings are designed in accordance with this section of SANS 10400-Part B, namely Structural Design.

When I last accessed the SABS online to see if these section of the regs was available, it wasn’t. However, there is no doubt that it will ultimately list all the other standards that designers should refer to when undertaking structural design. UPDATE: This is now available from the SABS at a cost of R369.36

Structural Design must be in Accordance with National Standards

It is essential that all structural systems are designed and built by professionals. It is also essential that all materials used are suitable and SABS approved.

Some of the SANS that are used by structural designers are:

  • SANS 10100-1: The structural use of concrete (specifically Part 1: Design)
  • SANS 10162: The structural use of steel
  • SANS 10163: The structural use of timber
  • SANS 10164: The structural use of masonry

There are also various SANS that focus on the basis of structural design and actions for buildings and industrial structures. These relate to a variety of actions that are caused by self-weight and imposed loads, wind, seismic action, thermal elements, geotechnical elements, and even cranes and machinery.

Lastly, there are international standards that should also be followed, some of which are available from the SABS.

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Dimensions

  91 Responses to “Structural Design”

Comments (86) Pingbacks (5)
  1. I live in pietermaritzburg. I want to erect an un-walled high roof (trusses and tiled verandah area. If the structure is attached to the main house do i need to have approved plans.
    When do I need plans for a garage, double carport or lap?

  2. My neighbour has built a very high (approx 3 m) tree house on my boundary wall .
    He did not ask my permission at all , so i have filed a complaint with the Cape Town Municipality.
    They have come back saying that it needs to be 3.5m away from the street, which it is definitely not, but did not mention the height restriction .
    As this is a wooden structure on stilts and it overlooks my bedroom window is this legal ?..

    • Hi Anthea, You must get the inspector to come out and make the call on this one. A tree house would be classed as “minor building work” that the council need it be told about it in writing by the owner. Another factor is that any structure on a boundary cannot have windows overlooking a neighbours property in that facing wall. Please keep in touch and let us know what happens.

  3. We are in the process of buying a smallholding in KZN Midlands. The main dwelling is approximately 30 years old and at that time it was not compulsory to submit building plans on an agricultural property. We took occupation 5 months ago and the transfer is still not registered as the seller has had issues with his rates settlement as he has still not submitted the As Built plans which were drawn 8 months ago. These plans were drawn up as Concrete Block under IBR and the bank approved our Bond as Concrete Block under IBR. We have only recently discovered that the house is actually a wooden house which was wrapped with chicken wire and plastered with cement. I believe a wattle and daub type structure. The house creaks a lot! Would you suggest we go ahead with this transfer IF the municipality approves the As Built plans or try to cancel the sale? Thank you

    • Hi Kerry, That method of construction used by the timber frame industry for many years does have SABS approval so is not quite wattle-and-daub, but is a cost effective way of building. I am surprised that the bank did not send a “competent person” to properly inspect the property before investing their money. I know it was some time ago but if you can try to find out who the builder was then you can get more info and put your mind at ease. You could also contact the Timber Frame Association and they should be able to give you the specs and builders names, their website: http://www.itfb.co.za/

  4. Please advise if possible where I can find the rules and regulations with regards to building a container home in Cape Town.

    • Nigel there are no rules and regs specific to container homes in South Africa. Part A of SANS 10400 mentions the Agrément certificate required for non-standard buildings.
      It is a “certificate that confirms fitness-for-purpose of a non-standardized product, material or component or the acceptability of the related non-standardized design and the conditions pertaining thereto (or both) issued by the Board of Agrément South Africa”.
      In turn, the Board of Agrément South Africa is a body that operates under the delegation of authority of the Minister of Public Works. However I am not sure of its current status.
      All I can suggest is getting hold of the Dept of Public Works. Alternatively any competent person should be able to help you.

  5. Good day

    I want to start my portfolio and I want to be as accurate as possible. I heard once that there are rules and regulations regarding how close a door should be to a window and how close a window should be to a toilet. I really want these kind of specifics rather than doing plans that are useless. Also, door and window schedules, my engineer tells me that they are made designed but it sounds unlikely. Is there a medium that offers this broad spectrum information or will it be independently windows, doors, roofs & trusses, plumbing etc. each in its own file?

    Help will be much appreciated.

    • If you are embarking on a career in building, I suggest you buy a copy of SANS 10400 from the SABS. There is also ample information on this web site which you are welcome to read. Our book on Owner Building also has lots of information.

  6. I want to build a block of flats behind my current property. I want to know the prescribed room size with an en-suite toilet and shower, a sink and sink kitchen cabinet.

    Regards

  7. I am interested in creating a home from refurbished shipping containers. What are the regulations regarding this type of design, and are there any standards which must be complied with?

    • All the usual regs apply, but for non-standardised materials and designs you need an agrement certificate. According to Part A of SANS 10400:
      An agrément certificate confirms fitness-for-purpose of a non-standardized product, material or component or the acceptability of the related non-standardized design and the conditions pertaining thereto (or both) issued by the Board of Agrément South Africa which is a body that operates under the delegation of authority of the Minister of Public Works

  8. Hi!
    I currently own property in a residential area, there is an existing house on the property, I want to demolish the house and build flats on the property. I would like to know what the procedure is. Assistance will be appreciated. Thank you

    • You will firstly have to find out from your local council planning department if it is possible to increase the density of dwellings on the property. Once you know that you can make application to demolish the existing building/s. You will then have to get town planning approval for the project first. This should involve the approval of all affected neighbours in the area. Town planning will need to see sketch plans of the proposed flats. then you will have to get final plans done by an architect or competent person and then get those submitted for approval.

  9. I’M buying an “Agricultural/Residential” Property in Chartwell, Johannesburg.
    The property includes a building ( Small House) that was erected in 1968.
    The Drawing supplied to me were fund are not been registered with the local council.
    I have request the seller to register the drawing and to add the small buildings that are not in the original drawing, but he refuse to do so at his cost.

    It is not a law requirement in this country to have the building legal before be able to sale it?
    Where can I find the regulation of this problem
    Thank you
    GCV

    • I am not aware of any law relating to selling houses as you suggest (viz ensuring the building is legal in terms of plans). It is however illegal to build a house without plans. Technically the local council could demand that the house be demolished if there are no plans – alternatively “as built” plans may be registered. You could approach the council and see what their attitude is. As things stand now, if the seller refuses to update the plans, I guess your choice is to bear the costs yourself, or cancel the deal – and notify the council of the situation.

  10. Hi there

    What are the rules re coverage of a property. We have already built on 50% of our property, does that rule still apply as we would like to build a garage with a room above..?

    • Chris it depends on the zoning bylaws – and varies. 60% is common, but check with your local authority. You would, in any case have to have approved plans to be able to build a new structure.

  11. Hello. I wanted to know is the bylaw of builiding a permanent structure using shipping containers? thanks

    • You will need to follow the National Building Regulations as far as possible, and also have an agrément certificate that confirms fitness-for-purpose of a non-standardized product, material or component or the acceptability of the related non-standardized design and the conditions pertaining thereto (or both) issued by the Board of Agrément South Africa. Part A of SANS 10400 covers this.
      It states:
      A4 Local Authority may Require Additional Documents and Information
      (9) (a)
      Where a local authority is not satisfied as to the adequacy or safety in use of any construction system, method, material, article or product which is proposed to be used in the erection of any building the local authority may require a test report or evaluation certificate in respect thereof.
      (b) the grade of material of all members;
      (c) the details of all connections between members;
      (d) the details of the corrosion protection to be provided; and
      (e) the details of reinforcement provided, including its strength and composition.
      (b) Any documentation contemplated in paragraph (a) shall be accompanied by a certificate signed by an approved competent person in which he shall certify that any apparatus to be installed has been designed to provide a standard of ventilation which complies with these Regulations.
      (b) On submission to such local authority of ––
      (i) an applicable report issued by the council or the CSIR; or
      (ii) any current Agrément certificate,
      the adequacy or safety of such system, method, material, article or product covered by such report or certificate shall be deemed to satisfy any relevant requirement for adequacy or safety prescribed in these Regulations, to the extent and under the conditions set out in such report or certificate.
      (c) A report or certificate contemplated in paragraph (a), issued on or after the date of coming into operation of these Regulations, shall contain the number of the Regulation which prescribes such requirement.
      NB
      The calling for test reports or Agrément certificates involves additional expenses and it is therefore important that this sort of information should only be required where it is really necessary and that, where it is required, it has been established that it will in fact give sufficient information to enable the local authority to decide whether or not to approve an application. In this connection it should always be remembered that where doubt exists, it is the building owner (or the designer appointed by him) who is responsible for proving to the satisfaction of the local authority that an application complies with the Regulations. It is not the local authority’s responsibility to prove that it does not comply.

      & another excerpt:
      Agrément certificates represent an entirely different approach. The original intent of the Agrément certificate was to present as complete an assessment as possible of any new building system, building component or building material, in addition to indicating whether it was considered suitable for use. The certificates also state which of the National Building Regulations, if any, the system or component may be deemed to satisfy.
      It should be noted that although test reports may be adequate to supply the information that a local authority might need to assess an application, the Agrément certificate serves an additional, very important, purpose in that it provides more information of a type which might be useful to anyone buying or promoting a new building system or building component. In addition, the Agrément certification process requires that certificate-holders have an acceptable and functioning quality management system in place, thereby providing assurance of consistency of quality of the end product.

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