Nov 152011

Building Regulations that Apply to Floors-Part J

A beautiful tiled floor

Floors can look beautiful, but what lies beneath has to have been constructed and built to the South African National Standards. You really do not want your beautifully newly laid floor cracking up because the foundations are cracking, or the tiles lifting because of rising damp.

The Application of the National Building Regulations that apply to floors (Part J of SANS 10400) are certainly not exhaustive. In fact, if you think of how much of our house is floor, it’s what we might, in South Africa, describe as a biekie min. But the authorities have, at least, increased this part of the document from a single page to nine pages (although these include a page of references to other SANS that need to be taken into account, and more than a page of definitions) plus a cover page, a Foreword, Contents page, an Annex that gives the official, legal Regulations (see below), a one-line Bibliography – on a full page, a couple of blank pages and some info about the SABS Standards Division.

Changes to the Law

Like all the other parts of SANS 10400, Part J, Floors, has two sections. One section covers the Regulations (the National Building Regulations and Building Standards Act, 1977 and all its amendments) and the other covers how they should be applied (previously what fell under the “deemed-to-satisfy” rules).

In terms of the Regulations (the law), there is one substantial change to the first general requirement that previously stated that any floor of a building must simply “be strong enough to safely supports its own weight and any loads to which it is likely to be subjected”. It now states that “any floor of any building shall be designed and constructed to safely support its owns weight and any actions which can reasonably be expected to occur and in such a manner that any local damage (including cracking), deformation or vibration do not compromise the efficient use of the building or the functioning of equipment supported by such a floor”.


In addition (and this hasn’t changed):

  • Floors must be fire resistant and where necessary, non-combustible.
  • Floors of laundries, kitchens, shower-rooms, bathrooms and toilets (hooray, they are no longer referred to as WCs!) and urinals must be water resistant.
  • Timber floors must have adequate under-floor ventilation.
  • Concrete floors supported on ground or filling must be constructed in such a way that moisture will not penetrate the floor slab.

As always, the Regulations state that these requirements will be “deemed to be satisfied” if the design and construction of the floor complies with this part of SANS 10400. However, if the local authority deems it necessary, certain other requirements may be needed. For instance the local authority may demand that the entire area within the foundation walls of any building be covered by a suitable damp-proof membrane, and in the case of a basement, or semi-basement, they may require adequate sub-soil drains to be provided under the floor to drain and therefore remove any water that accumulates.

Interestingly, the Regulations now define the word “adequate” in this context:

a) in the opinion of any local authority

b) in relation to any document issued by the council, in the opinion of the council

So if you’re not sure of anything that relates to floors and flooring, approach your local authority for guidance. They are obliged to help you.

Application of the National Building Regulations
as they Apply to Floors

In addition to a number of SANS that relate to building materials including boards, timber, concrete and fire testing of materials, the SANS states that Parts A (general principles), B (structural design), H (foundations), T (fire protection) and V (space heating) of SANS 10400 must also be taken into account when constructing floors.

The Application of the Regulations relate to:

  1. floors in wet areas as specified in the Act (that must be water resistant)
  2. suspended timber floors that are not exposed to the elements
  3. floors and slabs supported on the ground
  4. all timber used for building

There are some useful drawings that show how suspended timber floors should be built.


Bearing details for suspended timber floors on ground level


A competent person (civil engineering) shall design and inspect fills where the maximum height of fill beneath floors, measured at any point, exceeds 400 mm.

There are also specifications for maximum spans of floor joists:

  1. for those made with sawn SA pine for single- and double-storey houses
  2. for those made with laminated SA pine, Grade 5 or higher, also for single- and double-storey houses

Sawn SA pine


Laminated SA pine

Additional floor specifications relate to:

  • Flooring boards that must comply with SANS 629 and amongst other things should have a face-side width of at least 50 mm and not more than 140 mm, and tongued on one edge and grooved on the other, with square-sqwn or end-matched ends; and have tongues and grooves that produce a tight-sliding fit, and a flush joint on the face-side of the boards.
  • Strip flooring that amongst other things should have a width between 35 mm and 90 mm and a nominal length  of at least 460 mm (and tongues and grooves as above).
  • Particle board that should comply with SANS 50312 and SANS 1931.
  • Composite and plywood that should comply with SANS 929.

Additional guidelines relating to suspended wooden floors relate to the clearance between the joints and ground; ventilation; metal masonry anchors to be used and so on.

There are also a number of guidelines given for floors that are supported on ground or filling, but it is also stated that this type of floor should be designed and constructed in accordance with the requirements of SANS 10109-1 under the direction of a competent person (civil engineering) unless the building is to be used for storage or industrial purposes, in which case different guidelines are given.

This section also gives guidelines for underfloor membranes and filling beneath floors. Apart from anything else, a competent person (civil engineering) “shall design and inspect fills where the maximum height of fill beneath floors, measured at any point, exceeds 400 mm”.

So even if you go the DIY route, you’re going to need professional assistance.




  80 Responses to “Floors”

Comments (80)
  1. Hi,
    We have a floor (first floor) of rib and block, the builder has placed a concrete stairway from ground floor going 90 degrees to top floor. The height from step to ceiling on the third step is only 180 cm, therefor will not pass building regulation. My question is that when I cut a piece of the upper floor away, can I then use square steel tubing to support the above floor, and if so can I fix it from the third step to the ceiling (most likely place to put it), and lastly what is the thickness of steel that I must use?
    Thanks in anticipation.

    • Hi Lewis,
      This sounds too complicated and risky to ask and to answer in a post such as this. I suggest that you contact an engineer or another “competent person” to give you on site advice as this sort of fix needs to be done wtih the safety of all users in mind.

  2. Hi.

    I live in a flat which is 80 yrs old.wooden floors on beam
    My question is,can I remove the wooden floors n screed to
    Level n then tile

    • Hi Richard,
      It’s not clear from your description if you are on the ground floor or not. If you are on the ground floor then the “crawlspace” (the open space between the natural ground level and the beams) will need to be filled in and compacted before your damp-proofing, reinforcing and concrete floor is placed. This is not a small DIY job. As it is a block of flats then you will have to get approval from your body corporate first. If you are not on the ground level then it all depends on how the building was constructed. Many older buildings did not have concrete floors separating them. I would advise you getting an engineer in to inspect and let him/her decide if this can be done.

  3. Very nice blog post. I certainly love this website. Keep writing!

  4. Hi,
    What will the law say about tiling of floors and walls? And how many shower and toilets for 20 persons?

    • There’s no law as such Willie, only SA National Standards (SANS) that govern things like how tiles are made. The way tiles are laid has to do with good building practice and not “the law”.
      There are however safety aspects that must be followed – e.g. floors should not be slippery – and you will find these requirements in the building regulations under Part D, Public safety and in the Occupational Health and Safety Act.
      In terms of the number of showers and toilets required, this depends on the type of building occupancy that is specified in General principles and requirements. I have recently replied to the same question at least twice. Have a look at these links – scroll down to Seelen’s query & Elizabeth’s query. They should give you more information.

  5. I recently bought a holiday home (Wooden Cabin) and the inside flooring is falling apart. Is there any regulations on how wooden flooring should be installed? The timber is joined in mid air and not on the support beams and I have already stepped through one.

    I would like to take this up with the seller, since it was not disclosed to me during the sale and since I didn’t know better, I did not ask.

    • Any structure that is to be used as a “home” or dwelling requires approved plans. And yes there are regulations the specify how flooring should be installed. These include maximum spans for floor joists (depending on the timber used) and the timber used for floorboards. Most cabins (if I am imagining the correct type of structure) are supported on ground or fill – rather than on a solid foundation. In this instance, Part J of SANS 10400 state that the floor must be designed and constructed in accordance with the requirements of SANS 10109-1 and under the direction of a competent person (civil engineering). And it doesn’t end there. There are also regulations in terms of the ground or fill that the structure can be built on.
      It is not clear whether you simply bought the cabin or a property that had the cabin on it. Either way you are probably covered by the Consumer Protection Act.

      • Thanks Penny.
        The house was built in 2005. I bought the property with the cabin on it as the main dwelling.
        I have spoken to a building contractor in the mean time and the estimated cost to replace the floors is in the region of R250K.
        The contractor also confirmed my worst fears, the supporting beams are too far apart and the tongue and groove floor boards uses are too thin for pine.
        He is also not too sure about the job, since the walls of the cabin was built on top of the floor construction?

        I have contacted the NHBRC to get their opinion and will see my attorney next week.

        • Lijan, I have added to this page so you can get more of an idea what the NBR cover in terms of floors. The NHBRC manuals also have guidelines for floors, but unless the contractor who constructed the building was registered with them (which is highly unlikely because then they would have inspected the building several times during construction), they are unlikely to be very helpful. You would probably do better to approach the local authority, because it would have been their building inspector who approved construction at various points – unless of course the structure is illegal and was built without plans.
          I presume that the walls are timber? You would probably need to have the entire floor removed – leaving the sections under the walls. Then you might need additional plinths – or posts – and a proper system of beams. Once these are in place, attaching the tongue-and-groove flooring is not a big deal.
          You might want to get your money back and get out of the deal – though as soon as attorneys get involved, you will probably end up parting with most of the money their way. Good luck – let us know what happens.

          • Hi Penny

            I have gone over all the purchase documentation and was stunned to see a clause that nullifies my rights to the CPA? I did not sign the option that gave me the right to the CPA conditions and was crossed out?!?

            However, part of the Bank’s requirements for approval of my bond was a certificate of compliance to SABS 082. I do not have the full document, but I know that it contains the specification on wooden flooring.

            I have contacted an attorney that specializes in the construction industry and am awaiting his feedback.

            Thank you so much for your assistance!


          • Hi Lijan,
            Are you saying that the clause was crossed out but you did not initial it? If this is the case, you did not agree and therefore you do have rights to the CPA.
            SABS 082 is an “old” regulation. SANS 10082, Timber frame buildings was published in October 2007 and supersedes SABS 082:1988 (second revision). I suggest you visit your nearest SABS office and have a look at the document – better, still, purchase a copy from the SABS – It costs R329. If there is no certificate of compliance – then surely they won’t pay out?
            Good luck. Let us know what happens.

  6. I want to know what regulations in South Africa govern the
    installation of an exterior door in a building with particular
    reference to the required “step” between the interior and exterior of
    the house at a doorway.

    • Julien, any steps or stairs must comply with Part M of SANS 10400 (Stairways).
      For a single step, the important elements are:
      1. The rise of any step shall not exceed 200 mm.
      2. The going and width of any tread shall be not less than 250 mm, provided that where the stairway does not have solid risers, each tread shall overlap the next lower tread by not less than 25 mm.
      There are drawings on the page I have given as a link.

  7. What is the maximum deflection ratio for a timber floor where the floor is the first floor of a double story house? Has this chenged since 2008?

    The wooden beams span 4 meters.

    • Hi Miles,
      This is a question that an engineer (“competent person”) would have to answer, as there are many factors that have a bearing on the answer such as size and class of timber used, the load it is intended to support etc etc.

  8. Hi,
    Can you advise what the minimum requirements (depth, waterproofing, etc) are for a garage concrete floor above a residential flat below.
    Problem is that there was an oil spill in the garage that took a month before detection, and although now clean, there is a concern oil may leak through to the flat below.

    • I can’t give you anything more specific than the general requirements. And how will you be able to check this now? It’s anybody’s guess whether it will leak! Sorry I can’t be more helpful Don.

  9. Halo just need to ask a question about industrial concrete floors in malls and shopping centres. What is a class 1 class 2 class 3 concrete floor and the maximum and minimum tolerance of the concrete finish level and the method of casting and floating?

    • Albert, Finishes to concrete floors is covered by SANS 10109-2.
      The standard classifies recommended finishes in terms of abrasion resistance:
      Class 1 (50 MPa) is for very high abrasion including steel wheel traffic and impact (heavy-duty industrial, commercial etc workshops); Class 2 (40 MPa) is high abrasion including steel or hard plastic wheel traffic (medium-duty); Class 3 (30 MPa) is moderate abrasion for rubber-tyred traffic (light-duty). There is also a “special” class for severe abrasion and impact.
      Finishing processes for these are all trowelling twice or more (the higher the need for resistance to abrasion, the more number of trowelling operations will be required). Where a high resistance to wear is required, the finish should be floated after it has been spread, compacted and screened to level. Bull-, wood-, and power-floating are all acceptable methods. Further, floating and trowelling may be carried out mechanically or by hand.
      The SANS classifies maximum tolerances in surface flatness as measured with a straight edge supported at two points 3 m apart. Where a high degree of accuracy is required (usually for a thin finish), the max tolerance = 3 mm. Where a low degree of tolerance is required (for thicker finishes or where regularity is not an issue) the max tolerance = 10 mm. A medium degree of accuracy = 5 mm max tolerance.
      Note that this SANS is a 52-page document and it contains all the information you are likely to need. It is available from the SABS HERE for R240.

      According to the Cement & Concrete Institute (C&CI) Class 1 is suitable for floors that require minimum irregularity (i.e. where you are seeking perfection); Class 2 is suitable for most construction work; Class 3 is suitable for floors where regularity is not an issue.
      The C&CI has produced a very useful leaflet that you can download from our sister web site, for free. It is called Sand Cement Floor Screeds (scroll through the list) and provides information that is intended for architects, engineers and contractors who are specifying and laying floor screeds and toppings – to ensure that they are of the required quality.
      It deals with specifying tolerances and various finishes, including floating, but not in as much detail as SANS 10109-2.
      The C&CI also states that when it comes to the highest standard of surface regularity (Class 1), it may be necessary to use additional methods to finish the surface. They suggest a Concrete Society (UK) publication which you can also download from our Owner Building website. It is called Concrete Industrial Ground Floors.

  10. hi there. in the design of floor slabs i would like a confirmation on the following.
    1. on a 76mm fl.slab at 30mpa the steel indicated by the main contractor (which are a mining concern with no civil expertees.) ref 193 mesh. that could be done ?
    2. the cover from the bottom is 50mm std for the mine.?
    ive been in the construction for a lot of years and to my knowledge there is something out of standard.
    my concern is that in the outside temp of 35C + the floor will crack up.
    the total pour will be 700m/sqr in one go. hand floated. if the floor cracks up the responsibillity of the damage becomes mine. i need some back up, not to say any names but bldg regulations no so or so.
    thank u JDV.

  11. Hi. Do you know where in the Regs does it specify the width of a painted walkway in a factory?
    Also, how wide must the painted line be?

    • No Lindie, that isn’t specified in the building regulations. I think that painted factory walkways would fall under the Occupational Health and Safety Regulations.

  12. I need help with the following questions:
    1. What is generally used for floors and walls in operating theatres/laboratories in hospitals?
    2. Is there any regulation/legislation one should be aware of with regards to flooring/walls in these areas?
    3. The influence of cleaning and infection control in hospitals? Importance/will it affect choice of floors/walls?
    4. Who specifies interior building products such as walls and floors in both private and public hospitals?

    • Tendani my area of expertise is domestic, although the National Building Regulations do cover all types of buildings including hospitals. Part J covers Floors and Park K covers Walls, but the requirements are really quite general. I am sure that there must be some other very specific national standards that relate to flooring and walls in hospitals. I suggest you contact the SABS to find out which ones might be relevant.

  13. Hi there,

    is there anything against having polished concrete floors though out the home?


  14. What is the best sizes of joints between ceramic tiles? i have been looking through the national regulation book and cant find anything on it.
    5mm or 10mm?

    • This is not governed by any form of regulation! It depends on the effect you want to create, and just how regular the tiles are. Generally wall tiles have a smaller grout joint than floor tiles. Rule of thumb is probably 10 mm for floor tiles and 5 mm for wall tiles. Spacers are good for maintaining a 5 mm-joint when tiling walls.

  15. Is a builder permitted to construct a a first floor slab with concrete beams and polystyrene blocks? Does this sound right?

    • There are various methods that builders use with concrete beams. I will write an article about these methods and let you know when it is uploaded.

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