After the roof truss system, which is the main supporting structure of the roof, is constructed, you can proceed with the roof decking. The roof itself is the topmost part of the structure and is typically made from various waterproof materials. However, it’s important not to lay the roof material, such as corrugated sheets, directly onto the roof truss system. Instead, you need to build a sub-roof structure, which allows for secure attachment of the roofing material, provides flexibility in material choice, and allows for attic ventilation. The sub-roof decking consists of several elements, which will be listed in the order of their construction.
- Sheathing (Rough Decking): This is the initial layer of decking and serves as a base for the subsequent roofing elements. It is constructed using boards, plywood, or particleboard (it doesn’t necessarily have to be of high quality but must be sturdy). Sheathing covers the roof truss system and acts as the foundation for the roofing materials. The material should be nailed to each of the roof trusses with very small gaps between them. Make sure to extend the material beyond the first and last trusses where applicable.
- Waterproofing (Vapor Barrier): Any flexible, rollable material that doesn’t allow water to pass through can serve as the waterproofing layer. Common choices include roofing felt or more advanced roofing membranes. You can inquire about suitable options at construction supply stores. Install the waterproofing material horizontally, from bottom to top, with a 15-20 cm overlap.
- Counter-Battens: These are wooden battens that create an air gap between the sheathing and the final roof covering. The counter-battens are placed parallel to the roof trusses, and the spacing between them depends on the type of roofing material you choose (this information is usually specified by the roofing material manufacturer). For example, for corrugated sheets, the spacing should be 50 cm.
- Battens: The final layer of the sub-roof structure is the battens, which are typically 5 or 6 cm wide and 4 or 5 cm high, depending on the counter-battens’ dimensions. Battens are nailed perpendicular to the counter-battens. The spacing between the battens is determined by the roofing material selected (this information is typically provided by the roofing material manufacturer).
Now that the sub-roof decking is complete, you can proceed to install your chosen roofing material, such as shingles, metal roofing, corrugated sheets, or other options, based on your preferences and requirements. By comparing their pros and cons, you can select the most suitable roofing material for your project.