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RESIDENTIAL PROJECTS

THE RECENT FLOODS IN KZN HAVE IMPACTED RESIDENTIAL PREMISES AND BUSINESSES.  THE DAMAGES CAN BE ATTRIBUTED TO NATURAL EVENTS, HOWEVER, NUMEROUS FAILURES WERE AS A RESULT OF INADEQUATE ENGINEERING OR THE LACK OF IT. PMP ENGINEERS HAVE DEDICATE THIS PAGE TO MAKE HOME OWNERS AWARE OF THE BUILDING CODES AND THE REQUIREMENTS TO ENSURE YOUR SAFETY.

RETAINING WALLS

Although to the layperson low retaining walls might appear to be simple structures, the risks of badly built walls are acknowledged by engineers. When an engineer designs a retaining wall he or she will evaluate the soil and any rocks that are behind or below where the wall is to be built. They will also determine the best material for backfilling the wall and design drainage so that rain does not cause collapse.

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Part K of SANS 10400, Walls in the National Building Regulations (NBR) covers the structural strength and stability of all walls, including those that form part of a house or other building, and both garden and boundary walls.

They also deal with retaining walls which, by definition are intended to “resist the lateral displacement of materials”. If the wall is not designed the right way, it simply won’t resist the pressure of soil or other materials pushing against it, and it might collapse injuring or even killing people. It is for this reason that it is essential for all retaining walls to be designed by a competent Structural engineer.

FOUNDATION DESIGN

Foundations, Part H, of any structure, large or small, must be built to safely transmit all loads of the building to the ground. If foundations are not correctly built, walls may crack and at worst, could even collapse.

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In addition to 10400, there are other South African National Standards (SANS) that deal with foundations. For example:

  • SANS 2001-CM2 covers construction works for a variety of foundation types (strip footings, pad footings and slab-on-the-ground foundations) for masonry walling.
  • SANS 10161 covers the design of foundations for buildings in general.
  • SANS 10746-2 relates to information technology, specifically open distributed processing. The reference model for this standard is foundations.
  • SANS 12575-2 which covers thermal insulation products, specifically exterior insulating systems for foundations. This is highly technical and really only for the professional use of commercial/industrial installers of foundations.

While the National Building Regulations specify general requirements for foundations, it is the deemed-to-satisfy rules contained in SANS 10400 that give you more detailed information about how to ensure that your foundations comply.

Furthermore, the building regulations require you to have a competent person involved in the build of your home. You must also have plans drawn up according to the regulations AND the requirements of your local authority. This will ensure that the necessary controls are in place, and should guarantee that your structure will be safe and legal.

SUSPENDED CONCRETE SLABS

​A suspended slab a structural element  that spans an open area and is generally supported at the end of a span, this can be your floor on a double storey house or in the form of a flat roof.

A slab is design with consideration to the occupancy of the building, this must be done by a competent structural engineer, it is also advised that the engineer be advised when construction commences to monitor the compliance with regard to the design.

STORMWATER MANAGEMENT

The legislation states that the regulations should not be interpreted specifically as requiring roof gutters and downpipes if another suitable means of drainage has been provided to remove or disperse rainwater from the roof of the building. There are alternatives that architects sometimes prefer.

As always, the deemed to satisfy rules take this further. These state that any stormwater that emanates (or flows) from the roof, paving or any area that is in the immediate vicinity of a building shall not cause damage to the interior of the building, its structure or its structural elements. Steps must be taken to ensure that water does not accumulate in a way that “unduly inconveniences” the occupants of any building.

Part R also specifies other requirements of stormwater disposal arrangements. The system:

  • must not undercut foundations by erosion or flooding
  • must drain away from all buildings
  • must not allow water to accumulate against or close to external walls
  • must make provision for the drainage of any sites on the property that become waterlogged at any time
  • must be capable of being easily maintained and cleaned

Part R also specifies some of the disposal arrangements that need to be addressed, specifically:

  • those that allow rainwater to flow off the roof and away from the building, including roof valleys, gutters, and downpipes
  • those that channel surface water into stormwater drains that are either on the surface or below-ground, or channels – depending was is needed to remove stormwater from the site or to another part of the site where it will not affect the buildings

Ultimately, all drainage must  be shown on plans submitted to the local authority, and it is up to the local authority to decide whether these are suitable and adequate for each individual site. Also, it is the decision of the local authority whether stormwater may discharge into a stormwater system that is provided for a public road, or any servitude, or onto the street.