Conservancy tanks for Non-Water-Borne Waste Disposal

Firstly a conservancy tank must be built or a precast one can be bought. Then it must be sited beneath ground where the Building Regulations require.

You must then organise with your local authority or an authorised provider to pump the tank out on a regular basis.

Safety is Paramount when it comes to Stairways

It stands to reason that stairways must be safe.

Careful attention to detail on a house stairway that features wooden balustrades teamed with glass screens.

If stairs are too steep, and they don’t have railings, or if screens and balustrades are not strong and secure, people may fall with disastrous consequences.

What the National Building Regulations say about Stairs and Stairways

“Any stairway, including any wall, screen, railing or balustrade to such stairway, shall:

(a) be capable of safely sustaining 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 its functioning;

(b) permit safe movement of persons from floor to floor; and

(c) have dimensions appropriate to its use.”

What this means is that stairways, in addition to all the elements relating to them, must be properly designed. This takes us back to Part B of the NBR, which deals with structural design.

Like everything else, stairways must be designed to provide the strength, stability, serviceability and durability required for use. It is imperative that they are built so that any accidental overload won’t cause the stairway to collapse. It is also vital to takes steps to ensure that people won’t fall off the structure. If the sides of the stairs don’t have railings or screens this CAN happen – and it does (sadly) happen.

In addition to these general requirements, there are fire requirements that must be adhered to. These are outlined in Part T of SANS 10400 – Fire Protection, but when it comes to houses, those that are relevant mainly relate to basics (including the materials used to build your home). For instance you don’t have to have fire escapes, exit doors, escape routes, and that kind of thing.

SANS 10400 Stairways

As always, the South African National Standards give a good rundown on how we should build to ensure that we “satisfy” the legislation. The most recent Standard was published in April 2011; and it contains new guidelines that relate to both masonry stairways and timber stairways.

You will find Part M of the legislation towards the end of Standard, on Page 11.

It should be read in conjunction with several other Standards, including SANS 2001-CC1, -CC2, and -CM1 that deal with structural concrete works, minor concrete works and masonry walling; SANS 1460, Laminated timber (glulam); and SANS 1783-2, that deals with stress-graded structural timber and timber for frame wall construction; as well as several other parts of SANS 10400, specifically Part A (general principles), Part B (structural design), Part K (walls), Part S (facilities for people with disabilities), and Part T (fire protection). This is important because, for instance:

• Part S reduces the rise of the step (as indicated in this part), increases the width of stairways and the length of landings. It also has a requirement that solid risers should be used where stairs overlap the next lower tread, and another that specifies the need for handrails on both sides of the stairway.
• Part T increases the standard width of stairways as indicated in this part, disallows the use of spiral stairways, and requires solid risers for all buildings except those defined in Part A as D4 (a plant room that contains mechanical or electrical services that are necessary for the running of a building, and are usually left unattended).

Requirements of this particular Standard that relate to dimensions specify that:

• there must be sufficient headroom above any stairway: at least 2,1 m measured vertically from the pitch line of the staircase (see drawing below)
  

  Minimum headroom allowed on stairways

• stairs need to be wide enough for safe use, usually not less than 750 mm (see drawing below)
• the going (depth of the tread) and width of treads must be at least 250 mm (see drawing below)
  

  Allowable minimum dimensions of treads and risers

• treads of stairways that do not have solid risers must overlap the next tread by at least 25 mm (see drawing above)
• landings serving two flights in a straight line need to be at least 900 mm long and at least as wide as the flight of stairs
• there shouldn’t be a vertical rise that is greater than 3 m between landings
• single step risers shouldn’t be more than 200 mm
• doors cannot open onto stairways unless it’s onto a landing – and the landing then needs to be at least the width of the door (which must not obstruct people using the stairs)

Sometimes the dimensions of risers and going of treads vary in a flight of stairs. This variation should not be more than 6 mm. Further, dimensions of each individual step can be checked for safety by adding the dimension of the going to 2 x the height of the riser. This should be at least 570 mm and no more than 650 mm.

Tapered treads and winders (which are are steps that are narrower on one side than the other and used to change direction of the stairs without landings) are most common in spiral stairways. If they don’t form part of a spiral staircase, they must be designed to comply with the minimum tread and riser dimensions shown in the drawing above, and have a minimum going of 125 mm. The angle between successive risers (measured horizontally) must be constant (see drawing below).

To check the variation in going between tapered treads, measure each tread at the same distance from the narrow end

Stairways that incorporate winders – defined by the SANS as a “tapered tread that has a going of at least 50 mm and which is used in conjunction with non-tapered treads in a single flight” –  are permitted in our homes as long as there are no more than three of them, and the winder may not turn through more than 90 degrees.

Spiral stairways are defined as a “succession of tapered treads forming a curved stairway which extends as a single flight from one floor or landing to another”. These must be no wider than 800 mm and may not be used as an emergency route. There are also restrictions in terms of certain buildings where they may not be used, including theatres and other entertainment venues, schools, sports facilities, places of worship, exhibition bass, jails, hospitals and health care facilities, offices, hotels, dormitories and hospitality venues.

Prevention Against Falling

It should be common sense, but people don’t always see it that way, because stairs don’t always LOOK good with railings!

Essentially what SANS tell us is that:

If a flight of stairs is more than three risers high, it could be dangerous, especially if toddlers and old people use it. This is why it is essential to have some sort of protection to prevent falling.

This can be in the form of:

• a secure wall
• a screen of some sort
• railings or a balustrade – all of which should be at least 1 m high

Other issues include “openings”. If a child can fall through a gap in the railings, or if someone falls and their leg or foot gets stuck in the gap, it could end up really badly. The opening specification is similar to that which relates to swimming pool fencing: it shouldn’t allow anything with more than a 100 mm diameter to pass through it.

Handrails are also an important element. If a flight of steps continues for more than about five risers, there should be a handrail of some sort. And any sort of handrail MUST be securely fixed to the wall, screen, railing, balustrade or whatever! In some instances, for example when the stairs are wide (more than 1,1 m), it might be necessary to have a railing on either side.

If a screen is made of glass, it is vital that the glass used complies with the relevant SANS.

Timber Stairways

There are several clauses that relate specifically to timber stairs in SANS 10400 Part M (Edition 3, 2011). This section was previously not covered in the “deemed to satisfy” regulations.

Stringer Beams

Stringer beams support treads, and where these are not be wider than 1,2 m in double- and single-storey domestic residences and dwelling houses, they should be at least 48 mm x 225 mm. Grade 5 timber should be used and it should not be excessively warped.

Timber Treads

These must be at least 36 mm thick. Since timber stairways are designed in different ways, the options are that they may be:

• built into masonry walls with a minimum end bearing of 90 mm
• supported on a steel angle cleat that has minimum dimensions of 50 mm x 50 mm x 4 mm
• bolted to a wall with two masonry anchors per clear according to the manufacturer’s instructions

If anchors are used and embedded into a Grade 20 concrete (which will be 20 MPa), these anchors must have  ”a safe working load in sheer of not less than 1,25 kN, certified by the manufacturer”.

Materials Used for Timber Steps

Building Materials and Tests in general are covered in Part A of the National Building Regulations. In terms of timber, it should be treated against termites and wood borer as well as protected against fungal decay in terms of SANS 10005. For consumers, the important thing to look for is the product certification mark of a body that has been certified by the SA National Accreditation System.

Walls Support the Roof and other Loads

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.”