Walls & Roofs explores the key points of the glazing regulations as well as the pain points in installations.
The regulations for fenestration and glazing under SANS 10400 were intended to be straightforward, easy to understand and to make application simple and consistent with the rest of the building codes, yet the industry is still getting it wrong too often. Walls & Roofs spoke to a glazing consultant and South African Glass Institute (SAGI) competent person (glazing), Nick Wright, as well as Hans Schefferlie, executive director of the Association of Architectural Aluminium Manufacturers of South Africa (AAAMSA), about the apparent uncertainties and installation failures.
It is not so much about not understanding the principles as it is about not reading them properly, indicates both Wright and Schefferlie.
“The regulation was published in 2008 with an amendment in 2011, when the Part XA Energy Efficiency in buildings was added,” says Schefferlie. “The industry has no choice but to comply with what is published, but many either don’t read or just don’t do what the act specifies and don’t meet the deemed-to-satisfy rules. They are generally not adhering to Part N glazing or Part XA.
“Many industry role-players have been in business for 40 to 50 years and think they know it all, however, they haven’t kept up with the regulations. And it does not only apply to glass, it is a common problem in the building industry,” Schefferlie explains.
The gist of it
According to Schefferlie, the regulation simply states that if the area of the windows is less than 15% of the nett floor area per storey, it is business as usual. If it is 15% or more, the architects must do calculations in accordance with SANS 204. However all external glazed windows and doors must meet minimum air infiltration standards.
Wright adds that glazing to walls 10m tall or more, the glass for all the windows have to be designed following a rational design approach and has to be signed off by a structural engineer or a competent person (glazing) duly registered with SAGI (South African Glass Institute).
This sign-off also applies to overhead or sloped glazing, glass flooring, three- and one-edge supported glass, frameless bolted toughened glass assemblies and entrances, glass balustrading and glass for underwater applications in swimming pools. ,
However, he warns against just reading a part of the documents out of context since the devil is in the detail. “It is really quite a brief straight forward document, of which a lot is tables and diagrams. People should pick it up, read it and if they are still uncertain, get some training to understand it better.”
Glazing under SANS 10400 – key points
• Fenestration area ≤ 15% of net floor area (per storey) complies with minimum energy performance (deemed-to-satisfy) on presentation of air infiltration certificate.
• Fenestration area > 15% of net floor area (per storey) do calculations according to SANS 204 (rational design).
• Buildings > 10m in height – All the glass must be signed off by a competent person glazing registered with SAGI or a structural engineer.
Energy-efficiency is (XA) a must
Wright further points out that the XA part of the regulations requires buildings to be energy-efficient to slow the growth in demand for unsustainable electrical energy. “There seems to be a reticence from the design professionals to really get into it and it is as if glass is a grudge purchase. This is especially in the residential market, where people would rather have fancy-looking windows such as frameless doors than ones that work,” he says.
“An instant reaction is to reduce the amount of glass that goes into the building, but then more artificial lights are needed – solutions are available to make the glass more effective, such as external moveable shading devices, windows which open automatically to let cool air in or by orientating the building efficiently,” Wright explains.
Another common misconception that exists, says Schefferlie, is that functional glass is required to comply in terms of energy-efficiency, while this isn’t at all a requirement of the regulations.
“However, I think that if you’re serious about reducing the use of energy in buildings, it is imperative that the industry should switch to double glazing throughout, even if it means the demise of the steel frame, which cannot accommodate double glazing.”
According to Schefferlie, the most prevalent problems are water penetration of the framing and cracking of the glass due to incorrect installations. “The current metal framing used in the industry was designed in the previous century, and it has not progressed with recent developments in glass or the energy-efficiency regulations of today,” he says.
Wright, whose business it is to assist with, inspect and sign off installations, says that probably only 20% of companies that fit windows in South Africa complies with SANS 613 water penetration specification. “They can’t prove that the windows they install don’t leak, and if it happens that the windows do let water in, it is a breach of the National Building Regulations Part N.”
He also sees more and more aesthetic problems with glass. Scratches and damaged frames are often the result of main contractors damaging frames installed before plastering is completed. But the glass itself is drawn by the architect as a perfect plane and the client and the architect are unprepared for the reality of wobbly and distorted reflections. And often these issues are worsened when using double-glazed glass – .
Double glazing: Double the trouble?
“If double glazing is manufactured and installed in areas with different altitudes such as Durban and Johannesburg the double glazing will either blow up or go flat – even touch in the middle,” explains Wright. “Just like a shampoo bottle on a trip from the coast…And double-glazed windows are almost always slightly wobbly, on any kind of building, while architects’ 3D renditions generate the windows with a completely flat surface and perfectly reflective surface. So the clients and architects expectation is not realised on site. There are ways to avoid these problems, but they involve time and that means money.”
He advises architects and windows installers to manage clients’ expectations by putting up mock-ups and keeping them informed about the possible variability in appearance – even changing during the day – that accompanies double glazing and many of the high performance coatings that are available in South Africa today.
“Double glazing unit must be kept away from water – if the frame is not drained and the double glazed unit is not lifted from the aluminium on suitable setting block and if it sits in water, it will fail. Timber window frames are especially tricky and are only suitable for double glazing if the water can be kept from the edges or allowed to be effectively drained.”
He also warns that while it is positive that the local double glazing industry is growing rapidly, with prices coming within reach of many more projects because of the increasing competition, he expects many more site failures. The smaller manufacturers who get involved often do not yet have the required know-how. In fact, they are not even aware that they don’t know. “I have seen double glazing failing within three months because of a lack of knowledge,” he adds.
“I don’t expect so much of a problem in big buildings offices shopping centre and the like – they understand the need to employ specialist façade engineers and the like. However expensive houses often use more glass applications that are more complicated than a big office block. But the worst applications of glazing I’m seeing at the moment in any genre of building is high-end residential projects.”
Failures in retail
“The glazing for shop fronts in shopping centres is the second worst in my experience,” continues Wright. He mentions a prominent shopping centre in Gauteng as an example where one of the shop fronts failed – the glass separated from the ceiling and others that needed urgent repairs to prevent them from falling down. At a car dealership in Midrand, strong wind blew in the windows on some R4 million worth of cars.
“In such incidents the designer must show the design was correct and the installer must prove that they have installed in accordance with the design with appropriate workmanship and you have to be able to prove all of this,” Wright stresses.
Shopping centres are already stretching the envelope, with the Mall of Africa now asking for 6m tall shop fronts, according to Wright, who is involved with the project. Although it has been available in Europe for quite some time, locally the biggest safety glass plant makes glass 5,1m long. If it is imported, glaziers will face the challenge of installing bigger sizes than ever before, probably without the sophisticated machinery used abroad, unless someone steps up to bring the equipment over.
At the moment, many are getting away with not complying. “It appears that the regulations are not rigorously enforced by the authorities,” comments Schefferlie.
Wright, however, points out that the EThekwini Municipality has threatened and followed through with notices of eviction where inspectors found that the glazing does not comply with the regulations and the submitted plans. He sees that the industry is moving to better compliance.
“The onus is on everyone, all the way up the chain. We have a moral and legal responsibility to make sure that we design safe buildings,” he concludes.
Full thanks and acknowledgement go to AAAMSA and Nick Wright Consulting for the information given to write this article.
Advice for getting glazing right:
1. Read the regulations: SANS 10400 Part N and Part XA (section 4.4.4)If the window to nett floor area ratio is more than 15% read SANS 204 sections 4.3.4 and section 4.3.7.
2. Submit all plans to the building inspectors in terms of the NBR requirements for glazing.
3. Specify properly according to the regulations’ requirements and the aesthetic requirements of the project. If you do not feel confident doing this yourself employ someone to assist.
4. Ensure that the subcontractor meets the minimum requirements as specified including prequalification by submission of individual certification for each of the external glazing systems to be used
5. Allow time in the project to install and approve window mock-ups and samples.
6. Protect windows and doors from site damage by some means, preferably by installing them after wet works are completed.
7. Ensure that installation is delivered as promised.
8. Build up a list of trusted manufacturers and service providers.
9. Only buy from glaziers with appropriate product certification. Search for AAAMSA matrix on the AAAMSA website for more information on certified systems from individual manufacturers.