Nov 152011
 

Walls Support the Roof and other Loads

Walls Pix594 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 R147 excluding 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 K1 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 K2 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 K3 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 K4 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 K5 of the legislation states that Parts K1 to K4 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.”

  97 Responses to “Walls”

Comments (95) Pingbacks (2)
  1. Hi

    I live in a sectional title complex, I have discovered what I believe is rising damp in an exterior wall, when I had a look outside I discovered that the weep holes on that particular wall are below ground level (soil level).
    Firstly can this be the cause of the problem and secondly who is responsible to cure the problem.

    • Yes Peter that could easily be the problem. They probably filled in once construction was complete, without taking any precautions, e.g. painting on a bitumen compound (apart from the fact that it is bad building practice to fill above weep holes). Unless it says otherwise in the title deeds, then it is the owner’s responsibility to fix problems that relate to the section in which that person lives.

  2. Subject:
    Builder is a no show

    Message:
    Please help me! I have a builder that started to build a wall end of
    Dec 2013. He said to me that he will be done in 2 weeks time. I asked
    him to give me a quote for building a wall on the front with palisides
    and lifting the remainder of the wall with the precast slabs that is
    taken out. He said it is R20500 for all the work and I said we accept
    the quote and he can start. He started immediately with ripping the
    old wall off and digging the holes for where the pillars should be.
    They started building 7 pillars and it took about a week and a couple
    of days. after that he just started to not come for days. I sent him
    numerous emails to ask him to continue the work because our house is
    now completely open and that there was people in our yard the one
    night. He kept on saying that he is busy building the palisides and he
    will be the the next day. Every day being he will be there the next
    day and so days turned into weeks and now it has been more that 3
    weeks since he last were there. He refuses to pick up the phone when I
    call him and after that his phone is off. Yesterday he said he will
    try to bring the palisides and today he was speaking to me on WHATSAPP
    then i try to call him and he doesn’t answer saying it is noisy where
    he is. Finally he said that he has a trailer finished loading and is
    on his way. 2 hours later I try to call him and his phone is off, so I
    sent him a message and ask where he is and an hour later it shows
    delivered so I call again and it rings, the call then gets dropped and
    the phone is off after that again. Now he said to me that the lifting
    of the walls was not part of the qoute but he intended it to be as a
    favour, but to me he said it was part of the qoute in labour. His
    contact detail is:
    Rayno Diedericks
    RNH Projects

    • Jaco unfortunately I don’t know how we can help. I hope you have a proper written quotation and do not pay until the job is complete. Alternatively cancel the job.

  3. Subject:
    Internal wall

    Message:
    We need to close a portion of our factory. The wall will be internal and the lenght is 30m x 4.5m high between upright I beam steel couloms spaced at 10m onto a existing factory floor 150mm thick. Can we build a single wall without foundation? or must it be double wall. Springs area

    • Fred you shouldn’t build any type of wall without a foundation – that is if it’s built with bricks or blocks and mortar!

  4. i have tresspasses who have built a large block dwelling on my farm with no plans and without me the owners permission. they have now started building a septic tank 50 mt from on of my farm dams thus creating a contamination issue and increasing the rates and taxes on my farm of which i am responsible for paying. please advise as the municipality in ladysmith cannot/or do not wish to assist me.

    • Charmaine my only thought is that you should contact Carte Blanche! I am too far away to even begin to try and help. This sounds like a situation out of control.

  5. Hi ! I stay in Witbank, and need advise pleas.

    I am building a 1.8 m brick wall. The one side is 38m and the onther is 18m.

    Do we need to use brickforce?

    • Hi Liechelle, No it is not always necessary to use brickforce but it MUST be build with supporting pillars. You do not say the thickness of the wall and if it is a brick or block wall. You can safely build a half-brick wall about 100 mm thick to a height of 450 mm without piers (pillars), and to about 700 mm if two brick piers are built at 3 m centers. A thicker one-brick wall may be built to a height of at least 1.35 m without piers and to 1.8 m with 400 mm square piers at 3 m centers.

  6. Hi

    I live in Umhlanga Durban. My neighbour has occupied their home for the past thirteen years on their original plans, they showed a boundary which was never built, and there is a sand bank on their property that is slowly eroding, Only recently did they get legal occupation (friends with the building inspectors) and further their storm water soak pit was never constructed and inspected which is a requirement, I allowed them to run a storm water pipe through my property (temporary) to avoid their storm water collecting in my property.

    What recourse do I have with regards to the boundary wall and the storm water soak pit?, I addressed this problem with both the inspectors and the owners to no avail.

    please help

    regards
    selvan

    • Hi Selvan, Here is an extract from the Jhb bye-laws:
      “Where, in the opinion of the Council, it is impracticable for stormwater to be drained from higher lying erven direct to a road, the owner of the lower lying erf shall be obliged to accept and/or permit the passage over the erf of such stormwater: Provided that the owners of any higher lying erven, the stormwater from which is discharged over any lower lying erf, shall be liable to pay a proportionate share of the cost of any pipe line or drain which the owner of such lower lying erf may find necessary to lay or construct for the purpose of conducting the water so discharged over the erf”
      All the municipalities will follow the same bye-laws, so Durban-Umhlanga wil be the same.

      When it comes to the wall:
      The common law is that “in the absense of proof that a boundary wall is entirely on one of two adjoining properties, it is presumed to be half on one property and half on the other. Some legal authorities state that then each part is separately owned by the owner of the property on which it stands. Other authorities state that the wall is owned jointly in common by the owners of the adjoining properties.”
      It is up to you to make an arrangement with your neighbour about the wall, I do not see that you can force him to build.

  7. Hi, is there a regulation size for weepholes in boundary walls?
    My diagonal neighbour (we do not share any boundary walls) has dug a channel to our boundary corner and my property is getting flooded. I don’t want to block the flow of water completely and want to comply with building regulations, by-laws etc. He is threatening to sue me if I build a boundary wall or otherwise stem the flow of water from his property since I am lower.
    Thank you.

    • Hi Susanne, There is not any regulation for the size of the weep hole, so long as the wall remains stable.
      But the point is the lower lying erf is obliged to take stormwater from a higher erf if there is no other way for it to go.
      Here is a paragraph from the by-law:
      14. GENERAL CONDITIONS APPLICABLE TO ALL ERVEN

      2. Where, in the opinion of the Council, it is impracticable for stormwater to
      be drained from higher lying erven direct to a road, the owner of the
      lower lying erf shall be obliged to accept and/or permit the passage over
      the erf of such stormwater: Provided that the owners of any higher lying
      erven, the stormwater from which is discharged over any lower lying erf,
      shall be liable to pay a proportionate share of the cost of any pipe line or
      drain which the owner of such lower lying erf may find necessary to lay or
      construct for the purpose of conducting the water so discharged over
      the erf.
      Ask your local building inspector to arbitrate the matter.

  8. Hi, Ive been asked this question many times. Firstly, do wall ties and brickforce both need to be used in cavity walls and secondly, in how many courses of brickwork should wall ties be placed and how far apart should they be placed?

    • Hi Adam,
      Here is a pix of a common cavity wall. You can see the butterfly ties are spaced out every second or third brick along. This is done on every third course. Brickforce should be used in your foundation walls (this is not usually a cavity wall) if the soil you are building on is unstable in any way. In a cavity wall brickforce should be used above openings such as doorways, windows and any part of the wall that might be subject to cracking. In a single brick wall (a 230 mm thick wall) brickforce should be used every fourth course.
      Butterfly ties

  9. Where can I find out about the SANS speciffications on the material used for a dry – wall.
    Tank you

    • I suggest you contact the SABS and ask them which SANS specify dry walling materials. SAnS 10400 (i.e. the National Building Regulations) only govern the basics of timber frame construction.

  10. i need sabs for retaining walls. I am doing a project on them and i can’t get it. PLEASE

    • Go to an SABS library Mandla. You will be able to access all the SANS there.
      The only pointers I can give you are:
      1. The SANS define a retaining wall as “a wall intended to resist the lateral displacement of materials”
      2. As you will see from this link, if soil is retained by a boundary wall, the maximum permitted height of the retained soil is 2,1 m. This should be measured from the natural ground level in front of the wall. A balustrade wall not exceeding 1 m in height is permitted above the level of the retained soil. Plans are required for retaining walls.
      3. As you will see from this link, Part K of SANS 10400 establishes deemed-to-satisfy solutions for various walls and other elements, including garden and retaining walls.

  11. Good day Penny

    I am a new proud home owner and I have a few questions that I know you will assist me with.
    My neighbour has gone and ereceted a wall on an existing boundry wall without my consent or even consulting me about it.They have not reinforced it with any wire.It is now higher than 1.8 m.It looks very untidy because they did not even plaster the wall.My questions is :-
    1- Do they need a plan to have erected this wall?
    2-Are they obliged to have plastered the wall?
    3-Do I have the right to break the wall down ( the piece that they have now built)?
    4-How/where can I found out as to who the wall belongs to?

    • Morne, While the National Building Regulations specify that you can build a wall up to 1,8 m without plans (see minor building work), some municipalities allow walls to be up to 2,1 m without plans. They do though need to approve the build. They do not necessarily have to use reinforcing either.
      To answer your questions:
      1. Most local authorities do require plans for walls over 1,8 m – check with yours to see if this is the case.
      2. No they are not obliged to plaster the wall – but they are obliged to ensure that what they built looks aesthetically acceptable. But if they built without consultation with you (i.e. they did not reach an agreement with you that you would plaster your side), you have every right to put in an objection with the local authority and demand that he does plaster the wall.
      3. No you do not have the right to break down the wall. See this page for more information about positioning boundary walls and fences and ownership + rights etc.
      4. The link above goes briefly into ownership.

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