Corrugated and IBR roof sheets: Helpful information

Corrugated and IBR Roof sheets fall under the category of metal roof sheeting systems. These systems are also available in a variety of profiles, thicknesses, types of materials as well as coatings. In South Africa suppliers manufacture roof sheeting materials from aluminium-zink coated steel. This quality provides four times the lifespan of zinc-coated (galvanized) steel.

Roof sheet types

The coated metal type sheeting includes traditional zinc-coated mild steel (referred to as galvanized), and aluminium-zinc coated steel (sold as Zincal or Zincalume). We also find factory pre-painted galvanized sheets (Colorplus), and pre-painted Zincalume (Colorbond).

The primary distinctions in sheeting systems are:

• Pierced fix systems (fastened through the sheet with screws).
• Concealed fix systems (fastened by a clip under the sheet).

Roof sheet types and profiles for commercial buildings

In general, a large variety of sheeting materials and profiles available for commercial buildings such as shopping centres and industrial buildings exist. These types of buildings, due to their size, require specific properties and profiles that suit this type of application.

These are quite different from what is required for smaller buildings and the residential housing market. We therefore only focus in this article on the smaller commercial and housing market roof sheeting requirements.

Pierced fix systems

The most commonly used types of roof sheeting in South Africa are pierced fix system sheeting. There are different profiles available which include:

• IBR/Tufdek IBR roof sheets
• Widedek roof sheets
• Corrugated/Classicorr Corrugated roof sheets

IBR/Tufdek IBR roof sheets

So, what does IBR stand for in roof sheets? The name IBR is abbreviated for “Inverted Box Rib” and has become a household name in the South African building industry. The deep broad flute design offers excellent drainage characteristics with optimum weight versus load/span capabilities.

Tufdek IBR sheeting has a square fluted profile usually with an effective covering width of 686mm designed for use as side cladding or roofing material in commercial, industrial, and domestic applications.

Typical specification

Sheets have a 0.5mm thick AZ 150 Zincal profile.

How do you install IBR roof sheets?

Install the IBR roof sheets in the following manner:

1. Fix the sheets to internal purlins at 1,900mm centres, and to ridge and eave purlins at 1,700mm centres.
2. Use Class 3 self-drilling TEC fasteners and 19mm EDPM bonded washers for fixing.
3. Fix the sheets at every second crest on internal purlins, and every crest at eaves and ridge purlins and always consider manufacturer recommendations.
4. Stich the side laps at 500mm centres between purlins also according to manufacturer recommendations.

As a waterproofing measure use a lap sealant when you install the sheets at minimal pitches.

Tufdek IBR Roof sheet dimensions

The dimensions of this roof sheeting profile are:

• Cover width – 762mm
• Rib height – 17.5mm
• Minimum pitch – Slope > 15m = 10 degrees and where the Slope < 15m = 7.5 degrees

Widedek roof sheets

Widedek is a roofing profile designed to provide an economic alternative to deeper box rib profiles. This profile has the following benefits:

• It does not lose the aesthetic appeal of a square-fluted sheet profile.
• The Widedek profile offers greater spans and lower roof pitches than corrugated sheeting but provides 10% greater coverage than IBR.

Typical specification

Widedek sheets have a 0.5mm thick AZ 150 Colorplus material profile.

How do you install IBR roof sheets?

Install these roof sheets in the following manner:

1. Fix the sheets to internal purlins at 1,600mm centres, and ridge and eave purlins at 1,400mm centres.
2. Use Class 3 self-drilling TEC fasteners and 19mm EDPM bonded washers for fixing.
3. Fix the sheets at every second crest on internal purlins, and at every crest at eaves and ridge purlins, per the manufacturer’s recommendation.
4. Stitch side laps at 500mm centres between purlins. In this regard always consider the manufacturer’s recommendation.

For minimal pitched installations, use a lap sealant as a waterproofing measure.

Widedek IBR Roof sheet dimensions

The dimensions of this roof sheeting profile are:

• Cover width – 760mm
• Rib height – 29mm
• Minimum pitch – Slope > 15m = 10 degrees and where the Slope < 15m = 7.5 degrees

Corrugated/Classicorr Corrugated roof sheets

Corrugated is the traditional and familiar S-Rib profile for roofing and cladding applications. Generally, it is the oldest and most used roofing profile because of its ease of handling, excellent fixing properties, and commensurate strength.

Typical specification

The Corrugated roof sheets have a 0.5mm thick AZ 150 Zincal profile.

How do you install Corrugated roof sheets?

Install these roof sheets in the following manner:

1. Fix the sheets to internal purlins at 1,200mm centres, and ridge and eave purlins at 900mm centres.
2. Use Class 3 self-drilling TEC fasteners and 19mm EDPM rubber washers for fixing.
3. Also, fix the sheets at every second crest on internal purlins, and at every crest at eaves and ridge purlins, per the manufacturer’s recommendation.
4. Finally, stich the side laps at 500mm centres between purlins and always consider the manufacturer’s recommendation.

For minimal pitched installations, I recommend a lap sealant as a waterproofing measure.

Classicorr Corrugated Roof sheet dimensions

The dimensions of this roof sheeting profile are:

• Cover width – 762mm
• Rib height – 17.5mm
• Minimum pitch – Slope > 15m = 15 degrees and where the Slope < 15m = 10 degrees

Conclusion

This brings us to the end of the general roof sheeting discussion. In this article we covered the aspects of pierced fix systems. This included the popular IBR roof sheeting as well as the Corrugated roof sheeting profiles. My next article on roof sheeting we will cover concealed fix systems. In conclusion I advise that a registered architect, engineer is used whenever you plan roof sheet installation. A good idea is also to consult  SANS .

I hope that the above discussion gives some clarity towards an informed decision on what type of roof sheet covering you could use. If you have any questions concerning metal roof sheeting give us a call. We will gladly assist. Please bear in mind that Roof Buddies only attend to roof repairs, waterproofing of roofs, and roof painting projects.

Sincerely,

Peter