Nov 152011
 

Walls Support the Roof and other Loads-Part K

Building walls

It is vital that walls are strong, stable, waterproof and fireproof. The way that the roof is affixed to the wall is also very important.

The fundamental structure of a house is formed by its external walls, which must support the roof and take any other load that is built above. The section of the National Building Regulations that deals with walls is SANS 10400-K  and it has several parts, each dealing with building walls, and the elements of how both internal and external walls should be correctly constructed.

Changes to the Legislation

Like much of SANS 10400, Part K: Walls has changed quite substantially, both in terms of the legislation and the section that deals with The application of the National Building Regulations, which is the document prepared by the SABS and published separately to the legislation.

(NOTE: Previously SABS 0400, which became SANS 10400, was published by the SABS in its entirety, with the legislation and a Code of Practice which took the form of “deemed-to-satisfy requirements”. When the legislation changed on May 30, 2008, this was gazetted. The SABS then progressively updated its guidelines and published them over a period of years, as a series of individual documents. These are available from offices of the SABS and from the Bureau’s webstore, HERE. The new version of Part K was published on 29-03-2011 and it costs R517.56 including VAT.)

This article deals primarily with the changes to the legislation, and how it applies to building walls, rather than the South African National Standards.

Structural Strength and Stability of Building Walls

Part K 1 of the regulations states that, “Any wall shall be designed and constructed to safely sustain any actions which can reasonably be expected to occur and in such a manner that any local damage (including cracking) or deformation do not compromise the opening and closing of doors and windows or the weather tightness of the wall and in the case of any structural wall, be capable of safely transferring such actions to the foundations supporting such wall.”

This has been substantially expanded. Previously the legislation simply said the walls should be capable of safely sustaining any loads to which they would be likely to be subjected. It also said that structural walls should be capable of safely transferring such loads to the foundation supporting a structural wall.

There are various walling materials available, made primarily from clay and cement-based products. You will need to decide which is the best material for your particular purposes. Walls can also be built with stone or timber, but each material has its own set of methods to satisfy the requirements.

Solid brick walls normally consist of two brick skins that are joined together and strengthened with brickforce or brick reinforcing and/or wall-ties (a mild steel wire laid between some of the courses to add strength). The interior and exterior surfaces are normally plastered but may be fairfaced (facebrick). Concrete block walls are a more economic option and are often used for garages and outbuildings.

Water Penetration of Walls

Whatever materials you choose to use when you build, the method used for building walls must comply with Part K 2 of the regulations. Primarily they must be built to prevent water penetrating into any part of the building. All cavity walls must be well drained by means of weep holes above a damp-proof course. All cement bricks and blocks are relatively porous and should be plastered or rendered on both sides for thorough waterproofing.

Basements and semi-basements are also referred to in the “new” legislation, and any room below ground must be adequately waterproofed.

The legislation reads: “Where a building includes a basement or semi-basement, the local authority may, if it considers that conditions on the site on which the building is to be erected necessitate integrated designs for the penetration of water into such basement or semi-basement applicable to all construction elements or components thereof, require the submission of such designs for approval. Construction shall be in accordance with the requirements of the approved design.”

In recent years, a variety of alternative construction methods have been developed, most notably in the sphere of cheaper housing. These include the building of walls with insulated fibrecement panels; with fibreglass panels; creating the basic structure with shuttered no-fines concrete; using polystyrene sprayed onto a basic framework; or piling up sausage-shaped bags of sand and cement. If you want to use any altrernative method it would be best to contact your local authority planning division, or building inspector, for guidance.

Roof Fixing

Part K 3 deals with the way in which the roof of any building is attached to the wall and states that this must be done securely and safely and must be able to withstand any natural forces such as high winds or rain and hail. Specifically, it states:

“Where any roof truss, rafter or beam is supported by any wall, provision shall be made to fix such truss, rafter or beam to such wall in a secure manner that will ensure than any actions to which the roof may normally be subjected will be transmitted to such wall.”

While this clause of the legislation is basically the same as it was previously – one word has changed with forces deleted and actions replacing it – there are substantial amendments to the so-called “deemed-to-satisfy requirements” published in SANS 10400, Part K Walls. Similarly there are many changes – more so in the form of additions – to SANS 10400, Part L Roofs.

The Ways Walls Behave in Fire

Part K 4 deals with Behaviour in Fire, and state simple that, “Any wall shall have combustibility and fire resistance characteristics appropriate to the location and use of such wall”.

Brick, block and stone walls are generally accepted as fire resistant. Timber frame with timber or fibrecement cladding need to be certified, and you should check with the supplier regarding these rules for their type of walling, before you decide which material you are going to use for building walls.

Deemed-to-Satisfy Requirements

Part K 5 of the legislation states that Parts K 1 to K 4 will have been deemed to be satisfied “where the structural strength and stability of any wall, the prevention of water penetration into or through such wall, the fixing of any roof to such wall, and the behavior in a fire of such wall” complies with the relevant part of SANS 10400. This standard, “Establishes deemed-to-satisfy solutions for rain penetration and damp-proofing and contains simple design and construction provisions for masonry walls in single-storey and double-storey buildings and framed buildings that do not exceed four storeys; masonry balustrade walls and masonry free-standing boundary, garden and retaining walls.”

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Roofs-Part L

  171 Responses to “Walls”

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  1. Dear Penny,
    Please can you advise on the following:-
    – Do I have any legal claim against a builder for damp rising in my
    house?
    – what is the maximum legal height of walls internally allowed is one
    brick wide?
    my ceilings are over 4 M high with single break walling.
    My house is 2 years old. please can you advise?
    rgds,
    Mark

    • Hi Mark,
      Firstly was your house registered with the NHBRC? And secondly is the builder registered with them? Both of these have to be done by law. If both of these are true the you have to follow the procedure set down by the NHBRC and claim from the builder first in writing. Then after a set time you can claim from the NHBRC. You have 5 years for major structural defects, and if the dampproofing was not put in under the floor and walls, then that might be considered a stuctural defect. The full procedure is explained on their website here: nhbrc.org/consumer-info/
      Your “single brick wall” (the correct term is half brick wall) can be that high so long as it is not a load bearing wall and is only a room division.

  2. Hi, I have bought a home with a lapa extended from the back of the house. There has been a single brick wall build by the previous owner on a foundation around the lapa strengthened with brickforce and waterlayer applied. The lapa roof rests on its own legs and is not in contact with the single brick wall as there is a space between the wall and the lapa roof structure. Must the brick wall not be double or can one get away with a single wall built like that. The wall seems to be steady. Two small sliding windows on top of the wall and a sliding door has been installed in 2 sides of the wall. The two outer corners of the wall away from the house was joined correctly and the corners bordering the house seems to be joined with rods. Please advise.

    • Hi Ernst,
      You don’t say how high the walls are but I am guessing that if it is up to the lapa roof then it must be about 2m high. The regulations allow a wall up to 2.2m high without supporting pillars (piers), BUT the wall must be 220mm-290mm thick. With a single brick (correct term is a half brick) wall 90mm thick then you can go to 0,8m without piers and up to 1.7m with piers (490mm X 290mm) at 1,6m centers. These figures are extracted out of quite long tables that are too long to repeat here. You might be OK if the wall is anchored to the lapa uprights with steel rods as you mentioned. If you are concerned then get a “competent person” (engineer or architect) to have a look.

  3. Good day team.

    I would like to find out if there are any standards governing plastering that should be adhered to by a contractor when building new structures. More specifically are there regulations for depth of the plaster to cover brick, and also mixing ratios of the content.

    Thanks

    • Shaun there are standards – and there is good building practice. Not regulations as such. There are some leaflets that you can download FREE from our sister website Owner Building – here’s the link. I have also emailed you a copy of the C&CI publication, CONCRETE basics for building that covers the subject well.

  4. Good day,

    I am an insurance assessor dealing with a retaining wall that collapsed, allegedly due to a plumbing trench being left open near the wall and subsequent rain water washing away the foundations. We did not see the wall in its collapsed state, but looking at the wall as it has been rebuilt, it seems to me that it has not been built according to regulations that I have found, which seem to give a maximum height for a retaining wall of 1, 4 m. Is this correct? The wall in question is at least 1,8m high in places, and there are no piers.

    We did get some photos of the wall in its collapsed state, which also doesn’t show any piers. We also did not see the alleged trench in their photos. It was also higher than 1,4m. There are no weepholes in the wall, but it looks as if they are waterproofing the back and intending to put in an agricultural drain at the bottom, which I believe is acceptable, but not mentioned in the regs.

    Any comment you can give, particularly with the collapsed wall in photos 4 & 5, will be appreciated.

    • Mark, the regulations you need to refer to are SANS 10400: Part K Walls. The table you have referred to is in the old regs (SABS 0400 1990 – which you can download free on this site) and I am not sure whether it has changed. Probably not, although they might have added to it. BUT – retaining walls MUST have plans. And you are absolutely correct in terms of the need for piers. As far as the agricultural drain is concerned, that needs to be constructed BEFORE the wall is built. Have you investigated what foundations have been constructed? Seems to me they are getting it back up as quickly as possible. This may not be sinister – but it also probably isn’t legal. What I find strange is that from the photograph, the earth that is being retained does not appear to have shifted. You need to talk to an engineer, but it seems to me that the foundation trenches and the foundations were probably not adequate in the first place. This all points back to a need for plans drawn by a competent person.

  5. How close to a neighbours boundary wall can a neighbour build a garage? Does this require planning permission and if so where can one ascertain whether this has in fact been approved?

    • Hi Dino,
      If you go to your Local Authority with the address and erf number you should be able to see a copy of the plans and check if any alterations or additions have been approved. If you go to our sister site Owner Building there is a plan and an article on boundary distances and some guidance on Boundary walls and fences.

  6. What would be the boundary of my property?

    • All land is formally surveyed and boundary pegs are inserted at each point of the boundary (i.e. four points if the plot – erf – is square or rectangular.) Once people build they often removed the boundary pegs. You can get a diagram of your area from the Surveyor General’s office in Pretoria that will show where the pegs should be. If there is doubt as to the boundary, and there are no pegs, you may need to employ a surveyor to re-survey the plot and insert new pegs according to the Surveyor General’s diagram.

  7. How far from the road must the boundary wall be?

    • By-laws generally regulate the distance between boundary walls and the road – or any other land owned by the council/municipality. There is no one rule or regulation. Generally though this would be the boundary of your property.

  8. Dear Penny

    Good Day

    I need some clarity and assistance in resolving an issue with regard to the property I recently bought from Cosmpolitan Projects. I recently went to show the house to an architect friend of mine who pointed out structural defaults that I was not aware of. (Skew walls and windows) . He alluded to the fact that the Inspector should not have approved the building until Cosmopolitan broke down the wall to rectify the mistake and re-built it. I also consulted a builder in the area who also concurred that the kitchen wall must be broken down to fix the mistake. In this case I called the bank (FNB) and informed them of the problem and they referred me to the Chief Building Inspector at the City of Tshwane. What
    I want to know and need assistance with-is whether as a home owner I am within my rights to demand that Cosmopolitan Projects breakdown the wall anf fix it before I occupy the house or what other remedies are available to me to resolve this matter. Your urgent response will be appreciated!

  9. Good afternoon

    I bought a house 10 years ago in Stillbay. It is a thatched roof house and on applying for approval to have the roof changed to an “aluzink”roof the building inspector found that the wall between my house and garage is not a firewall. (It was bought that way and apparantly it was changed from a seperate single garage to an attached double garage.) As the wall seperating the house and garage is a normal external double wall,how do I change it to a firewall?

    Thanks

    • You can probably use a non-combustible cladding. I am surprised the building inspector didn’t make any suggestions. What I would do is to approach the local authority and ask them to give you acceptable options.

  10. Hi Penny
    I live in a sectional title unit. The boundary wall around my garden has developed cracks and bricks have started falling off. Now I know this is an issue for the body corporate to repair, my questions relates to the regulatory issue of height, width etc. The walls cover 2 sides and are higher than 1.5m but are only single brick width and have no supporting pillars. I am led to believe that the walls, over 1.5m should be double-bricked and have supporting pillars every couple of meters of running wall. Can you provide further information on the requirements?

    Thank you
    John

    • John the magic height is 1.8 m – which links to “minor building works” & here too (scroll down to the end). See if the links I have provided here help you, otherwise get back to me. I will in the meantime try and get something onto the website regarding walls in general – because there are also building standards relating the the NBR – supporting pillars, brick force and so on – that must still be adhered to, even if the wall is lower.

  11. hi penny
    we have a partly boundery wall. i had a problem with smoke emissions if my neighbour are making fire. after complianing of the smoke he errected a wooden structure on top of boundery wall without my consent. the result of the closure of the wall is having an adverse effect on my natural light and ventilation. i have complained to the local authority, but the neighbour instead is applying to build a concrete structure. what are my rights as a neighbour in this regard. i have objected against the idea and forward my objection to the local athourity.
    waiting for your comments
    regards
    danny

    • The problem with smoke is that, even if the wall is quite high, it will rise. If this happens often, and your neighbour refuses to do anything about it, then you can take legal action in terms of it being a “nuisance”. If it is really bad, you could report your neighbour to the local council for air pollution. But if the smoke is from an occasional braai, you won’t get much joy.

  12. Hi Penny,

    I am busy renevating a house in a holiday complex where the allowable building size is 200 m2. I have had a snag. The one foundation wall started cracking as it was on a steep slope, we proceeded to build a new wall parallel to it. We put steel reinforcing inbetween the two walls and filled it with a strong mix of concrete.Unfortunetly this has now added 10m2 to the building size. I am led to believe that if one renevates there is a ruling that one can over or under shoot the m2 size by 10% of the plans due to these unforseen circumstances. Is this correct?

    • Peter that is not an NBR rule. It is obviously a rule that the complex developers imposed. So they would be the ones who would complain, if anybody did. They would also be the people who may or may not have made a rule regarding renovations. Since you are reinforcing a foundation wall, I hardly think this has any bearing on “allowable building size”. I would think it’s a safety factor that has to be carried out.

  13. Hi

    I have a block brick border wall of about 1.2 meters high that I have build on my own expense. I would like to know if I could build on top of it and attache a small store room to it BUT making sure not encroaching my neighbors property. What are my rights?

    LOLO

    • I hope you had plans to build the wall, because if you don’t, the local authority could make you demolish it. You certainly cannot build on top of it, attaching a room, unless you have plans that have been approved. Apart from anything else, you would need to ensure that you have proper foundations for the structure. And if you were to build on the boundary, you will need you neighbor’s consent (via the local authority).

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