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.”

>

Roofs-Part L

  171 Responses to “Walls”

Comments (166) Pingbacks (5)
  1. Hello ,

    need some advise, we are building wall 98m long , partly retaining ( almost completed) . in some places heights of the wall 3.5 -4m high . there is some disagreement on reinforcements and foundation between builder and engineer . is there any independent specialist who can come on site for an opinion . Thank you

  2. I intend to build a small house with solid stone walls in the Waterberg. The founding conditions are good with rock close to the surface. What thickness of wall will I require for strength and water tightness and are there and special requirement for the foundations?

    • You will have to submit plans to the local council because the law says that ALL buildings ANYWHERE in SA must have plans. So you will have to have a “competent person” draw up the plans and they will specify the foundations for your specific site. You can read more about foundations here: foundations

  3. Hi

    I want to convert a totally unused space right next to my house, currently paved, into an entertainment area. I plan to build a 6m long wall witch will have double brick colums every 1.5m apart. The columns will reach from the foundation to the roof and will be strengthened with brickforce, but the wall will only be a single wall. The planning is to build the wall 2.5m high.

    The roof cover will be normal zink and the roof is a flat roof. Beams similar to those of the house that currently carries the roof will be properly linked with those on the existing house and will be placed across the width of the area to support the roof. Brandering will then be installed to fit PVC ceilings.

    At the open end of the new entertainment area, a 4.8m steal beam will be installed to enable the installation of a 4.8m sliding door and treli-door, and to support the weight of the small amount of bricks that will be duild up to roof level.

    Will this be accpetable, or must I build a double wall. I am trying to save on costs as far as possible.

    Aston

  4. Hi Penny. I live in a townhouse complex and we are submitting plans to have the sectional title plan amended. The one building houses 3 garages. 2 of the garages belong to one section in the complex and the 3rd garage belongs to another section. Currently there are no dividing walls between the garages. The Land Surveyor has said that in order to measure the garages to allocate them accordingly there has to be a dividing wall between the single garage for one section and the double garage for the other section. Can you give me some specifications for this wall? i.e. single skin, brick wall and to what minimum height. I cannot find any information in the building regulations. Thanks for your help.

    • This is far too specialized Jill. I don’t think anything in Part K Walls even hints at this. You will probably find there are specs in the townhouse regs.

  5. Hi
    Please help me …. I’m busy building a double storey house . My neirgbour lodge a complaint about my high roof walls . Yes I agree I went a bit more brick course I wanted a high roof . My challenge ? Must I break down the walls I already build to meet the plan standard or my neighbor needs or is there anything I can do to save my walls please assist . This is real working on my health my high blood pressure is on top
    Kindly assist me … If I must break the walls I will just to be at peace
    Thank you
    Regards

    • Hi Litha, Every suburb in South Africa has height restrictions and they can be different for different suburbs. Your plans were approved for the height that is on your plans. You cannot just change the plans as you want without getting approval first. You need to check what the maximum height is that is allowed in your area from the building inspector. You might be under the maximum allowed and you will just have to submit a rider plan. If you are above the height allowed and you want to change the plans and ask for approval from council they will require you to get neighbours permission to go beyond the restrictions. Now that you have a complaint lodged I am not sure that you will now get your neighbours approval for the walls to be higher.

  6. I need to know the following : The beamfilling between trusses was allways done with 110mm brick line only partly due to the fact that the wallplate for the trusses is continuous and a 230mm wall will be unnecessary. According to one builder, that claims that there is a new regulation stipulating the beamfilling as a 230mm wall, we now have to cut the wallplate into pieces to accommodate the 230mm beamfill. Is this allowed and/or what is the regulation?

    • Hi Dirk, It is the first time that I have heard of something like this. Please give me a few days to make a few enquiries and I will repost another as soon as I get an answer for you. It does not make any sense to compromise the fixing of the wallplate by cutting it into pieces.

  7. Good Day

    I have recently built a house with parapet walls. My concern is that whenever it rains or when there is dew the water runs down the walls and leave water streak marks. I am being told by the builder and the engineer that this is normal and I should expect this to happen. This also tends to be happening under the window.

    Please inform me if I am wrong to complaining about and please advice me on what I can do to prevent water from running down the exterior walls of the parapet walls and under the window sills.

    Your assistance is appreciated. Thanks

    • No you are not wrong in complaining. It really depends what they mean by “normal”, and just how much damage this causes. The only thing you can do is get an independent engineer to consult on the issue – to see if it is in fact a problem. That will though cost you.

  8. Hi there, I have converted a garage to a bedroom and en suite bathroom, we built a new 110mm interior wall. After how long can you tile on that wall? Thanks

    • Hi Ehren, Normally as soon as the plaster is dry, that should be in a day or two depending on the weather conditions and altitude above sea level.

  9. In brick work affter how many line should I use brickforce?

  10. Hi there
    I wonder if you can help me.
    I own an apartment that is located on the roof of a building in Cape Town. The outside patio wall = the exterior wall of the apartment complex.
    My current tenant has now lodged a complaint with the city of cape town, saying this wall is too low. (It is pretty low, but it was like that when i bought the apartment about five years ago and obviously it was also that height when the tenant decided to rent the place).
    What are my responsibilities in this regard? is it the responsibility of the body corporate, or mine? And surely it would have needed to pass a building inspection at the time it was built?
    I can’ afford to build the wall higher, but I also feel that if it should be done, it should be the responsibility of the body corporate as the wall is part of the building’s construction?
    And what is the actual rule in terms of wall height? (It’s on the fifth floor).
    Your advice would be appreciated.
    Thanks

    • Ella I think the minimum height is 1 m. Part K of SANS 10400, Walls states “4.2.5.1 Balustrade and parapet walls shall not be less than 1,0 m in height unless unauthorized access of persons to the edge of a flat roof or similar structure is excluded by a physical barrier properly erected and monitored.”
      But if it is an exterior wall then it would indeed be “common” property and therefore the responsibility of the body corporate. Essentially common property in a sectional titles scheme comprises all the land on which the scheme is situated and all exterior parts of buildings. Roofs, the exterior (outer portion) of walls and foundations also form part of the common property, as do gutters, downpipes and boundary walls.

  11. Hi

    I hope you can direct me to the documents that deal with the issue I have. The wall of my bedroom, which has the window and therefore also has an exterior side is only one brick layer thick.

    A handyman I called in to help me with damp in my bedroom explained that exterior walls should be doubled (apologies about the misuse of terminology here).

    Do I have reason to make a complaint about this (the wall not being up to standard) to my landlord as I am trying to get out of my lease.

    Thanks for the help.

    • Nichole that is not necessarily so. As I point out in my book Owner Building in SA, external walls may be “one brick” or single leaf (see drawings below) – in which case the wall is the thickness of the length of the brick (to allow for bonding) – or cavity walls – in which case there is a gap between two skins of brickwork – defined in the NBR as “wall that consists of two parallel walls (called leaves) of either solid or hollow units, that are built side by side and tied to each other with wall ties so that there is a cavity of width at least 50 mm between the leaves”. Walls may also be collar-jointed – defined in the NBR as a “wall that comprises parallel single-leaf walls with a space between them that does not exceed 25 mm, solidly filled with mortar and tied together with wall ties.” Cavity walls are not mandatory in South Africa but they are advisable in areas that have high rainfall in winter or summer. There are though numerous specified dimensions in the National Building Regulations including the thickness of units (bricks or blocks) used to build external walls; as well as maximum wall heights and wall areas where there are openings. These though would be indicated on the approved plans. Many other things need to be taken into account as well including lintels, reinforcement and of course damp proofing. Frankly your landlord should be sorting out any damp proofing issues. If he won’t you might be able to get out of your lease because of that rather than the thickness of your walls.
      Wall types
      Single-leaf external wall

  12. Hi,

    I recently discovered that I have a lateral crack in my house walls, I live in a pan handle property so access to initially view this was not possible when I bought my property about 2 years ago.
    The crack is going from ground up and I believe this is where a new room was joined to the existing wall.
    from what I could see, there is no expansion joint in the wall.
    The walls are about 4m high. how serious is this? because if I go up into my ceiling, I can see the light outside.

    Thanks

  13. Hi, a developer built a holiday house in Clanwilliam for me 4 years ago, there are damp problems on the inside of the exterior walls, and i have only now notices that there are no weepholes or cavities, i.e., the exterior walls are 230 mm brick walls. Is this legal and do i have recourse. The plans are approved by the municipality and the Nhbrc was paid their fee ?.

    • Wayne if there are structural issues you may still be covered by the NHBRC warranty which is for five years. If it is just damp, you’re out of time. Was the house approved by the council and an occupation certificate issued?

 Leave a Reply

(required)

(required but will remain confidential and not be published)

   
© 2012-2017 SANS 10400 • © Notice Sitemap • Contact Us • Terms & Conditions Suffusion theme by Sayontan Sinha