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. What is the right mix for screed in a public toilet?

    • It really doesn’t matter where you are laying the screed. A suitable mix would be 130 litres of concrete sand for each 50 kg of cement + enough water to produce a nice, workable consistence.

  2. Hello
    What are the regulations regarding garage floor with an integral door to the rest of the house? I seem to think it needs to be 150mm below but would it serve the same purpose if it were 150mm ABOVE the house floor. It is an old house and the ground level outside is the same as the floor into the house – there is no step into the front entrance.
    Many thanks.

    • there are no regulations stating that a garage floor must be higher or lower than the rest of the house. The regulations for Foundations Part-H say that the outside ground level must be a minimum of 150mm below the DPC (Damp Proof Course). The DPC is the plastic waterproofing strip that is built into the wall between the foundation and the brick wall.

      • Is this correct? I am under the impression that a garage floor must be at least 80mm below the floor level of the house where there is direct access from the garage to the house. As for “oil stores” this prevents burning oil etc. from entering the house. Maybe the by-laws differ between the municipalities.

        • Pierre neither Part H: Foundations nor Part J: Floors of SANS 10400 mention garages. Garages are mentioned in Part T: Fire Protection. e.g. doors to any garage have to have a certain fire resistance. There is also a clause that relates to parking garages for more than 10 cars that states: “The floor of any occupancy classified as J4 shall be of non-combustible material and shall be not less than 10 mm lower than the threshold of any door leading to any adjoining room or space.”
          There might be some sort of municipal by-law – your local authority will be able to advise.

  3. Hi id like to know in a project whose responsibility is it to do levels or finish floor levels between the architect and the engineer..??

    • It’s the builder’s responsibility to do the levels and finishes. It is the responsibility of the competent person (could be an architect or an engineer) and the local authority building inspector to check that these are done correctly.

  4. Good day, I am extending my house by 40 sqaures, just an extra room and en suite. On the plan it says the exterior wall should be 280mm, which means it should have a gap of 50mm between inner and outer bricks. When I checked after thd builders were done, the gap is only10mm. They have laid the foundation concrete and juat built up a couple of courses, the slab has not been laid yet. Could they still build the cavity wall with 50mm gap from the slab upwards or must the same gap / cavity be from the very first course all the way to roof height?

    • The gap in the foundation walls usually gets filled with cement/mortar or concrete and then the walls above the slab should have a minimum 50mm cavity and be built with wall ties evenly spaced throughout.

  5. Hi, we’ve build a second storey with timber and it wasnt done by qulified builders, however they have years of experience.

    We having endless problems with the shower, with water running down to the ground level. I’ve had several plumbers in to fix the problem that created more problems on the ground level. Now we have cealings that need to be replaced everytime it happens. We’ve stopped using the shower due to the fact that we cant find someone that knows what they doing. Advise please.

    • First lesson: Always use qualified builders. Second lesson: Only qualified registered plumbers should be used – that’s the law. Third lesson: Go back to the first and second lessons and employ people fully qualified and equipped to do the job. Cutting corners is more costly than doing it right the first time.

  6. Do plans have to be submitted to local municipalities for the partial enclosure of a patio?

    • Keith if you are using a solid building material e.g. bricks and mortar or even timber-frame, your local authority is likely to require plans. There is also the issue of classification or use of the area. This needs to be specified on the plans. But the municipality has the authority to either call for plans or decide that it is “minor building work“, in which case plans won’t be needed.

  7. Hi, What constitutes as a “Basement”? Is there a certain percentage of the space that needs to be below “Natural ground level”? Or as per the building regulations, is it just a space below ground floor? If so, then what qualifies as the “Ground floor”?
    I am designing a parking space that is mostly underground, would that count as a basement level?


    • Marnus, presumably if you are designing a “parking space” you are a competent person and therefore know or have access to this information. The only advice I can give comes from the definition of “storey” in the NBR:
      a) the ground storey shall be taken as the storey in which there is situated an entrance to the building from the level of the adjoining ground or, if there is more than one such storey the lower or lowest of these,
      b) a basement shall be taken to be any part of the building which is below the level of the ground storey,
      d) the height expressed in storeys shall be taken to be that number of storeys which includes all storeys other than a basement
      You will find the full definition in Part A of SANS 10400.

  8. Hi, I live in Pretoria and I removed the joists which upheld the wooden floor above my basement. The basement and the room above now have a concrete roof/ floor. I would like to re- use the original pine wood planks over the concrete slab instead of tiling. I’m told that solid wood must be placed on top of wooden strips that are nailed into the concrete yo prevent rotting and promote circulation of moisture. Could you please provide your technical suggestions or recommends in this regard? Many thanks, Fatima

    • Fatima if you look at Part J of SANS 10400 – some of which is covered in the link I have given you – you will see that there is a section for Floors supported on ground or filling – that gives some information. Wood though is not mentioned specifically and the method you mention isn’t either. If you Google “wooden flooring on concrete” you’ll see there are various ways including something similar to what you describe but using “sleepers’ underneath which I presume would be quite hefty – and they would need to be to carry the weight of the wood. You could probably also screed the concrete with mortar to which a waterproofing compound has been added and then paint with bitumen and/or use a DPC and then place the wood on top. A problem with sleepers/strips etc is that these affect the height of the ceiling from the floor. BTW I presume you are talking about using the “wood planks” (floorboards) that were originally fixed to the joists. Many modern wood and simulated wood products are manufactured to be attached directly to a screened (so it is smooth) concrete surface. Sorry I can’t be of more help.

  9. Hello,

    What are the regulations regarding wooden flooring and Air Bricks/Ventilation?
    Should all houses with wood flooring have air bricks or some type of ventilation?

    • In the National Building Regulations themselves it states:
      “Any suspended timber floor in a building shall be provided with adequate under-floor ventilation.”
      SANS 10400, Part J Floors (which is the SABS “deemed to satisfy” regs) states:
      “Ventilation of the subfloor space in suspended ground floors shall be provided by means of openings spaced not more than 2,4 m apart with at least one opening within 0,75 m of each corner. The total area of ventilation openings provided shall be not less than 1 000 mm2 of unobstructed air passage per square metre of floor area. All ventilation openings shall be fitted with corrosion- resistant screening of nominal aperture that does not exceed 1,2 mm.
      NOTE A 0,220 m × 0,170 m airbrick has an unobstructed area of between 0,006 m2 and 0,009 m2. Accordingly, one such airbrick is required to serve between 6 m2 and 9 m2 of flooring.
      “Floor joists in suspended ground floors shall be set on and skew-nailed to sole plates that have minimum dimensions of 38 mm × 76 mm on top of sleeper walls (see figure 2). Sleeper walls shall be provided with sufficient openings to ensure good cross ventilation.
      NOTE At the junction of solid and suspended floors, e.g. at verandahs, ventilation pipes might have to be provided underneath solid concrete floors. Where sleeper walls are used, ventilation openings of size at least 115 mm × 75 mm spaced at 1,0 m centres should be provided.”

  10. I want to buuld a 2nd storey … not sue if I should go wood or concrete…. what is best …. and can I build the 2nd floor with wood what would be the consequence in

    • Hi Patrick, If you want to build a second storey on a single story house then the first thing you will have to find out is how strong your foundations are and if they can take the weight of a second storey. Timber is a much lighter material and many houses have a second storey built with timber. The timber materials have to be specified by a “competent person” and approved by council.

      • What is the cost of using timber vs concrete to floor the second storey

        • That is called homework and you have to phone the timber and concrete suppliers and get prices from them and then compare for yourself, we do not do quotations etc, sorry.

  11. Hi there.

    I purchased a brand new flat from a develloper. After 14 months the tiles started coming loose and the grout falling out. The developer states that he has a 6 month warranty and after this time takes no responsibilities for defects. Is there some sort of law i can use to make him fix the tiles without me having to pay for the damage?

    • This is clearly a case of shoddy workmanship, however I don’t there is much that you can do except name and shame the developer – e.g. on Hellopeter.

  12. Subject:
    Concrete Floor Alignment
    I have just purchased a brand new two bedroom apartment and a garage,I paid cash for the Garage R55000. The garage was handed over as Voetstoets ,the flooring is concrete : rough raw finish , not skimmed straight and smooth as i expected to be.Hills and valleys on the floor
    Is there any regulations regarding my complaint.

    • Rajen it depends what your contract states. If it was to be skimmed or screened so that it was smooth this should have been specified. However if it is really sub-standard then you might have recourse via the Consumer Protection Act.

  13. Could you please advise me on the legal requirement for a wooden floor in a double story dwelling. There are two separate families living on either level.

    • Christine the floor would need to be constructed as shown on this page for suspended wooden floors. I am assuming that the fact that two families live in the dwelling is a factor – probably due to noise. This is not covered by the National Building Regulations.

  14. Hi,
    Please could you advise what the regulation is with regards to having an allowance between the internal and external floor levels. I’ve been told it needs to be 150mm, but this seems a bit excessive.
    I have been told my 30mm height is not up to building regulations.

    • Hi Dean, the regulations do say the the minimum height between the average surrounding ground level and the top of the internal floor slab is 150mm. Normally you would not have a 150mm step down through a doorway. There should be a landing or patio that leads out through the door then a step or steps down.

  15. hi there
    What is the requirements to build a woodern floor the maxium distance between beams
    thank you

    • Gareth all the information given in the NBR relating to suspended wooden floors – including spacing of joists (which are the beams) – is in the article on this page.

 Leave a Reply


(required but will remain confidential and not be published)