Walls & Roofs is celebrating its 15th year of existence with 100 days of specification.
Over this period, we will bring you the top tips of some of the leading companies in the built environment.
5 TIPS from Safintra on metal roofing:
1. Be conversant with SANS 10400-L.
In general terms, it requires any roof covering to resist the penetration of rain, and be capable of being effectively repaired, despite ageing of material.
It also stipulates however, that roof coverings, whilst being suitably maintained, shall resist, with appropriate reliability over its full design working life* (≥ 15 yrs):
• temperatures from -10°c to +80°c
• effects of condensation at the under surface,
• chemical attack from common atmospheric gases,
• saline atmospheres in marine environments, and
*DESIGN WORKING LIFE: assumed period for which a cladding system is to be used for its intended purpose, without severe abuse or poor maintenance and without major repair being necessary.
WHY IS THIS IMPORTANT?
– Planned and preventative maintenance of a roof is critical if it is to perform for it full design working life
– Roof materials have to be selected in accordance with the corrosion expected in that environment.
– Good design must ensure that roof systems are correctly ventilated or moisture proofed to prevent under-sheet condensation which can corrode both sheet and fasteners.
2. Ensure that all self-supporting metal cladding is strictly in accordance with the requirements of SANS 10237: “Design, testing and installation of metal cladding”.
(“Cladding” refers to both roofing and side cladding.) The minimum purlin spacings are stipulated on the basis of metal type (coated steel, aluminium etc) thickness of material, and its tensile strength.
If purlin spacings exceed the SANS stipulations, insist on seeing valid test results to verify the spanning capability of the profile. Lack of same indicates that the profile may fail in application.
WHY IS THIS IMPORTANT?
– Under-specification may result in liability for failure falling on the professional team.
3. Take into account the corrosivity of metals according to ISO 9223.
ISO 9223 defines six broad environmental categories for the corrosion rates of metals (excluding paint coatings), and stipulates coating thicknesses for each category.
In addition to geographic location, micro climatic conditions that can have a detrimental impact on the corrosion performance of a coating include:
• Marine: wind-borne chlorides
• Swimming pools: condensation
• Chemical processes such as galvanising
• Contact with uncoated/painted steel
• Green or incorrectly treated timber: CCA(copper, chrome, arsenic)
• Fallout from stacks and extractors
• Intensive animal farming: sulphur and ammonia compounds
• Exposure to highly alkaline products: cement powder and mortar
WHY IS THIS IMPORTANT?
– Incorrect material specification can result in warranties being refused by the metal material manufacturer.
– Premature failure of materials can result in liability for incorrect specification being passed back to the professional team.
4. Don’t compromise on the quality of fasteners.
The minimum specification for corrosion protection of fasteners shall be equal to or better than the corrosion protection coating to the cladding.
Primary fasteners (i.e. fasteners used to attach the cladding to the supporting structural members): Never use rivets, mushroom head drive screws/nails or conventional nails.
Secondary fasteners (i.e. to stitch side laps in cladding or to attach flashings and other ancillary items to the cladding): Neither nails nor open rivets may be used for this purpose.
All roofing material manufacturers are very clear on fastener classes which they will accept in specific environments to issue a warranty on their sheeting
WHY IS THIS IMPORTANT?
– Fasteners are the smallest component of the roof system and yet the single greatest cause of sheeting failure. They are also often the least expensive single component on the roof so to compromise on the quality is foolish and short term. The cost of replacing a small component such as fasteners is vastly greater than the small cost saving made at time of installation.
– Premature failure can result in liability for replacement being passed back to the installer and / or professional team.
5. Always check the compatibility of different metal roofing components, especially sheeting and flashing materials.
Incompatible materials being used adjacent to each other will result in accelerated corrosion of their protective coatings. It will also void warranties on the material. All material manufacturers and roofing manufacturers are very precise on their stipulations. Ask for technical advice from Safintra if you are not sure or download the Design and Installation Manual on www.safintra.co.za.
WHY IS THIS IMPORTANT?
– We have seen many instances where flashings were made of a different metal type to the sheeting, resulting in metal corrosion or early failure, and substantial liability being passed to the contractor and/or specifier.
– The metal material producer will not accept responsibility, nor will the manufacturers of sheeting and flashing, especially if they are different suppliers.
5 tips for installing IsoBoard thermal insulation as a ceiling:
1. IsoBoard can be installed directly below the existing ceiling as a retrofit.
If you have a damaged ceiling, perhaps following water damage, or if you just need to add insulation to improve the living experience in your home or business, you can fit IsoBoard directly below the existing ceiling, saving the mess and effort of removal, whilst adding the comfort and temperature control that only IsoBoard provides.
2. Always choose IsoBoard board lengths to run from wall to wall.
Secure the board positively using screws and adhesive to fix to perimeter brandering on the board’s ends, and concealed fastening clips and adhesive to fix the board to the central brandering. Remember, the IsoBoard will last as long as the building stands, with no drop off in design performance, so proper installation is vital.
3. With a maximum length of 8m, you may find in some instances that you need to butt joint two or more boards together to install a ceiling in a large room or passage.
Always plan the ideal natural position for this joint to occur in your room, as you will always need a cover strip of some sort to hide this joint. Butt joints are never easy to disguise when using IsoBoard, so anticipate using cover strips where butt joints are necessary, and always ensure the joint occurs over brandering, to secure the board ends, and have a firm support for the cover strip to be fixed to.
4. Anticipate painting IsoBoard for residential and commercial ceiling applications.
While IsoBoard is white and washable, one should always plan to paint the Boards if used in residential applications, or if otherwise close to the eye-line. Paint the board with an initial filler coat to repair any scratches arising from transport and installation, using water-based paints or wood stains only.
5. Choose energy efficient lamps to pair with your IsoBoard insulated ceiling.
Please use energy efficient or LED lamps when installing recessed down-lighters within IsoBoard, to avoid potential heat build-up around the lamp fitting, which may otherwise result in a few millimetres of board shrinkage around the light fitting. The rule of thumb is that if the lamp isn’t too hot to hold when operating, it is suitable for use with IsoBoard.
5 Tips from iTe Products for hassle free installations:
1. Check the screed for moisture
Use the best screed moisture tester you can, and do as many tests as you can to make sure that the screed moisture is below that specified for the flooring to be installed. Take a photo of the results to put in the file for future reference should a problem occur later. And then use a moisture barrier if the levels require.
2. Check the screed for soundness
Hairline cracks are a sign that maybe the screed is hollow and delaminating from the slab. Tap it with a rod or golf ball to hear if it sounds hollow. If it does, advise the customer before proceeding.
3. Check the screed for flatness
Vinyl flooring installed on uneven or rough screeds will mirror all the imperfections and look poor. Customers want their floors to look stunning; they are paying good money for that. LEVELite self-leveller delivers just that – a smooth solid surface.
4. Check the temperature
If it is too cold, the flooring may not flatten out properly, and expand when temperatures rise, causing peaking or bulges. A really good idea is to acclimatise the flooring for at least 24 hours before installation.
5. Check the adhesive
Use the correct adhesive for the particular flooring and the conditions that the flooring is to be installed in. The wrong adhesive may result in failures, and if applied incorrectly can also give problems. When you use the recommended adhesive in the way the manufacture insists on you using it, you will seldom experience problems.