IBR rooftop sheeting is a square fluted profile with an adequate covering width of 686mm, intended for use as side cladding or roofing material in business, mechanical and private structures. The name IBR is abridged from “Inverted Box Rib”. In 1958 when IBR roof sheeting was introduced to the South African market, it has become the most popular sheeting used in the construction of commercial and industrial buildings.
The 686 “IBR” is an angular trapezoidal fluted profile sheet. This particular profile has a bold angular appearance and makes it a desirable choice as it has many advantageous characteristics such as its strength to weight ratio, which proved optimum load span consistency and the broad flutes ensures excellent drainage. The IBR profile has an adequate cover of 686mm and is manufactured in thicknesses (gauges) from input material ranging from 0.27mm to 0.8mm. The manner in which IBR is manufactured is with a stiffening rib in the broad flute, therefore, minimising the waves in the broad flute of the profile. If sheets without the stiffening rib are specified no claims for waving (oil-canning) will be accepted.
The Structural Capabilities of
Lengths Available in IBR Profiles
IBR sheets are cut in lengths of up to 14 metres. With a length tolerance of -0 +5 mm. Sheets lengths up to 15.8m are available on enquiry. For bullnoses and curves, the maximum allowable transport height is 4.3 metres.
- When using IBR, the recommended minimum pitch for roof slopes over and above 15.8m is 7.5º, and for slopes less than 15.8 m is 5º;
- The minimum end laps for roofs pitches >15º is at least 150 mm and 250 mm for other roofs. Side cladding end laps should be at least 100 mm;
- We recommend that end laps on roofs <7.5º are sealed with a bitumen sealing strip to ensure water tightness.
Our recommended fixing procedure
The required number of IBR sheets is calculated as follows:
- Length of structure plus gable end overhangs – (minus) 70 mm;
- The number of sheets = 0.686 m (Cover width of sheet).
The result of the calculation is then rounded up to the next sheet. IBR must be fixed with one corrugation side lap. With the narrow flute uppermost and fastened through the crests of alternate flutes to purlins, using 65 mm Tek screws into steel purlins and 90 mm Tek screws for timber roofs, each fastener must incorporate a 25 mm bonded washer. For side cladding, broad flutes can be fixed externally with fasteners in the web of the flutes. Side cladding can be fixed using 25 mm Tek screws with a 19 mm bonded washer. For a quick calculation, three fasteners per sheet per purlin can be used.