Safety and Stability When Doing Excavations
Are Top Priorities – Part G

Excavations are not always necessary when we build our homes, but it often is, even if the ground is reasonably flat and level. Part G of the National Building Regulations deals with excavations and their safety.

The Importance of Stability

One of the reasons it is always wise to employ, or at least consult experts is so that all building operations are safe. However it is the owner of the property’s responsibility to take precautionary measures during building operations – or to make sure that precautionary measures are taken.

For instance, major excavations may weaken or even damage the safety and stability of a property, so it essential that precautions are taken to prevent this from happening.

Another factor is that during excavation, there are always open spaces, so it is important that these are safe at all times.

In any case, according to the building regulations, if excavations are likely to be any deeper than 3 m, the property owner must get written authorisation from the local authority before digging begins. In this instance the local authority is likely to specify precautionary measures that must be taken, and/or they may insist on the appointment of an appropriate “competent person” to oversee the operation and be responsible for it.

Even if written authorisation is not required, property owners planning to excavate must let the local authority know at least seven days prior to the operation commencing.

According to the regulations, anyone who doesn’t comply with these requirements will be considered to be guilty of an offence.

Foundation Excavations

SANS 10400 states that to comply with the building regulations as they relate to excavations, a professional engineer or other “competent person” should design foundations for excavations that are more than 3 m deep.

Other guidelines include taking excavations for foundations down to firm, natural ground, unless approved measures have been taken to ensure stability of a foundation cast on fill.

The bottom of all foundations should be flat, level and therefore absolutely horizontal – UNLESS they are cast on solid rock that is stable. If a concrete foundation is placed on solid rock, the rock must be clean and dry and it should be “stepped or dowelled” to ensure that there isn’t any lateral movement that could cause the foundations – and then possibly also the walls – to crack.

Stepped foundations on ordinary ground are acceptable, but these must have horizontal and vertical surfaces.

Generally, the guideline is that the bottom of excavations for the foundations of external masonry (brick, block or stone) walls – other than those built on solid rock – should be not less than 300 mm below the level of the adjoining finished ground.




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Penny Swift is a highly regarded journalist and author of books relating to homes and construction.

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  1. Elizabeth Ritchie

    We own a property in Noordhoek Cape Town. Recently our neighbour who owns the adjacent vacant plot started to excavate so that he could access his plot. Of course he chose to do it in a howling south easter which didn’t help my shock as I received no notification that this was happening !! He has dug into the slope at the bottom of the plot to create ‘ track’ so that he can drive his 4 x 4 up onto his plot. He has also leveled a large area so that he can enjoy a glass of wine up there with his family. We have no objection to this of course. However what are the regulations regarding excavation works? I have read that the local authority must be informed. Is this correct?

    In addition we would like to raise the height of our existing wooden fence on the boundary to ensure privacy over our deck and pool. The platform that he has excavated impinges directly on out pool. Apparently raising the fence is not allowed. The plot owner has objected as it obscures his sea view. Is this correct?
    PLease advise.

  2. You won’t necessarily be notified that excavations are to take place on an adjoining plot, it depends on the Local authority. However, the law is explicit when it comes to the owner of the plot’s responsibilities in terms of excavation. The law states that:
    “The owner of any site shall, at least seven days prior to the commencement of any excavation” … that is related to “a building” … “notify the local authority in writing of his intention to excavate.” Even though he appears to be excavating for access, I think it would be safe to argue that the excavations are related to his intentions to build. Further, he has a responsibility, in terms of the law (the NBR) to ensure that the excavation is safe and does not undermine the stability of the property or any services on the property.
    Also, if the excavation is any deeper than 3 m, he MUST “obtain the prior written authorization of the local authority for such excavation”.
    In terms of your fence, have a look at the article on Minor Building Work on this site, as well as an article I posted on our sister site recently, that touches on Minor Building Work (scroll to the end). You will see in the latter article that you do not need plans to construct any form of freestanding wall or fence, as long as it is no higher than 1.8 m and does not retain soil. All you have to do is notify the council that you will be raising the wall to 1.8 m. If it is already higher than this, you will need plans; and your neighbour cannot reasonably prevent you from getting approval, particularly if it is a privacy issue.

  3. Elizabeth Ritchie

    Thank you for your prompt and informative response!

  4. Hi, I want to buy a pice of land. My intention is to build on it. It has a servitude running right through the middle of it. I dont want to build on the servitude though. I only want to build in the space where there is no servitude. But i am not sure if i can do this. I have emailed council and phoned them i have asked the lawyers, my architect and a builder that we might use none of them can tell us if we will be able to build. I want the property but i have to know if i can build on it. Please help me. I have the plot layout and line of servitude. Please help us. Thank you Shaun

  5. I am a little puzzled as to why you aren’t getting answers from the people who should be able to provide you with answers. What sort of servitude is this? Normally the title deed will state clearly what building restrictions there are on a plot. You have every right to insist on seeing the title deeds before making a final decision.

  6. My neighbour has excavated an area approximately 4m wide and 3m deep right next to the foundations of my boundary wall which is partially a retaining wall. He has supported the wall with some timber and metal poles but after the rain, some of the clay underneath the wall collapsed. I am seriously concerned that the wall will suffer damage only visible over the long term. The building inspector did not seem to have a problem with the work. What recourse do I have in the case of future damage? How can excavations be allowed right up to the foundations?

  7. If a building inspector is involved, can I assume that your neighbour has submitted plans? It also isn’t clear what he is excavating for. If some sort of structure is being built right against your boundary, I would have thought that your permission would have been required.
    However, if all the work is being done legally, in terms of your local authority’s requirements as well as the requirements of the building regulations, and the building inspector is not bothered by your concerns, probably the only recourse is to put something in writing to both your neighbour and the local authority, that in the event of future damage caused by the affect of undermining your wall’s foundations, you will hold them jointly and severally responsible for any costs you may face. This would, though mean that you would have to take the legal route if there is long-term damage. And another factor to consider is what would happen if your neighbour sells.
    Perhaps you should, in any case, get an independent engineer to inspect the work now. If an engineer is concerned, then this will alter the whole scenario.

  8. Robin, this might be helpful. “Lateral Support You have a duty to your neighbour to ensure that when digging or excavating on your property you do not withdraw lateral support to his property provided by yours, unless you replace it with artificial means such as a retaining wall.
    “You may not, for instance, dig below the level of his land along your boundary if it is likely that this will result in his soil being washed away when it rains. Your excavations must not threaten the stability of any part of any building on his land. He may successfully sue you for damages without having to prove that you were negligent if damage does result from your action.” Reader’s Digest Family Guide to The Law in South Africa.

  9. Hi,

    How high can you fill a clean plot? The neighbourhood is next to the
    sea so everyone wants to build as high as possible for best view, but
    the clean plot where they are starting to build has now almost filled
    a meter from our ground level. Isn’t that too high?

  10. Hi Wikus,
    The regulations do cover excavations. But many sites require fill to be brought in to infill foundation walls before the concrete slab is thrown. This has to be clean according to the regulations. There might be some localised regulation that deals with height restrictions in your area. If they have raised the level overall by more than one meter the concern would be more about the soil stability when building on soil that has not had time to stabilize. Contact your local planning department and ask them for advice.

  11. Martina Theunissen


    what are the rules/law regarding building on an old graveyard? Do you need to get some form of permission from City council or other authorities?


  12. Martina there is a form that has to be filled in re the NBR for “sensitive” sites – and graveyards may fall under this. I am not sure. But I think more likely it will be a zoning issue, and so the local authority would need to give permission. You certainly can’t simply go and built on an old graveyard.

  13. Hello i have a question, do South African Law regulate the draw-well, do we have to pay a fee for having it our property.

    I am foreign and i heard that you can not have a house for living and your office at the same property, can somebody gimme which legislation dictate that?

  14. I am not sure what you mean by a draw-well – a borehole perhaps? At the moment there is no fee for borehole water, but there is talk that this may be introduced at some stage. Property owners do though have to pay to have their own pump installed and maintained.
    There is nothing to stop you from working from home, however you may need a license from your local authority for certain types of work. This would usually apply to businesses that attract traffic.

  15. I need to register a company as specialize in excavation but the problem is i don’t understand the principles with regards to pricing, please assist?

  16. You need to go to a business adviser Mpadi. This site is about building regulations, not registration of companies.

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