What Is Over-Roofing? Benefits and Step-by-Step Installation Guide

When it comes to upgrading your roof without the noise, mess or expense of a full tear-off; over-roofing might just be the innovative solution you need. This modern technique enables you to install a new roofing layer over the existing one, saving time and reducing waste.

At Onduline, over-roofing can be done with our lightweight, waterproof and easy-to-install roofing systems. Whether you are renovating or extending a building's lifespan, Onduline’s smarter over-roofing solutions for terrace or home offer a visually appealing and greener way to roof - combining performance, aesthetics, sustainability, convenience and ease like never before.

Pre-Installation Checklist for Roofing

Before you begin, here’s a quick checklist to ensure a smooth and safe over-roofing.

• Thoroughly clean the existing roof surface, ensuring it is free from dirt, debris and obstructions.
• Inspect the existing roof structure for damage or weak spots.
• Confirm that the roof pitch is suitable.
• Use the Onduline Roofing Calculator on the homepage for accurate estimation of required products and accessories, such as
• Onduline Classic or Onduvilla best roofing sheets
• Nails or screws with sealing washers
• Ridge, verge and all other accessories for eaves and ventilation

Once you are ready and checked off the list, you are all set to begin. Now comes the most exciting part of bringing your new roof to life! Onduline’s systems for roof extension are designed to make the process straightforward and stress-free.

Roof Installation Made Easy: Follow These Clear Steps

1. Inspect existing Roof

One of the key advantages of over-roofing is that removal is usually not necessary. If the existing roof is stable and structurally sound, simply clean it, repair any small damages and proceed with batten installation. This saves time and reduces waste as compared to the complete tear-offs.

2. Conducting a Roof Deck Assessment

This step is essential for both safety and performance. Check that

• The existing structure must support the new roof load.
• Purlins or battens are spaced correctly (45 cm for roofing tiles, 60 cm for roofing sheets).

3. Installing Water Diversion Flashing Elements

Proper water management is critical. Onduline offers a complete set of flashing components:

• Apron flashing for sealing intersections with vertical walls or chimneys.
• Verge and Ridge Flashings to protect the sides and top of the roof from wind and rain ingress.
• Onduline Sealing Band for joining sheets and flashings with an extra watertight seal.

Each component is designed to work seamlessly with Onduline sheets, ensuring long-lasting protection. Lay the sheets over the secured battens, starting from the end opposite to the direction of prevailing winds for optimal stability and protection. Simply fix the house roofing sheets; its corrugated profile aligns with Onduline Classic sheets, offering

• A secondary waterproof layer
• Improved insulation
• Reduced condensation
• Ventilation through micro-channels

4. Incorporating Exhaust and Intake Vent Systems

Ventilation is often overlooked but is essential for roof longevity and indoor comfort.

• Eaves Ventilator Strips allow airflow into the roof base while keeping pests and debris out.
• Ridge Vents release hot, moist air from the attic or loft space.

This airflow helps prevent condensation, mould growth and heat buildup, especially in warmer climates.

Expert Recommendations for Installation Excellence

• Use only Onduline fasteners (nails or screws with washers) for a secure, watertight finish.
• Lay the sheets against the direction of prevailing winds to prevent water ingress.
• Maintain correct overlaps: 1 corrugation side overlap and 20 cm end overlap for standard slopes.
• Fix at every corrugation at eaves and overlaps and alternate on mid-span purlins.
• Always refer to Onduline’s installation guides as roofing solutions for home for slope-specific recommendations and spacing charts.

Mistakes to Avoid During Roofing Installation

• Using non-Onduline fixings: This compromises waterproofing and may void warranties.
• Skipping ventilation: Without airflow; condensation can damage the structure and insulation.
• Ignoring slope requirements: Low slopes without underlay increase the risk of leaks.
• Poor alignment or overlap: Misaligned sheets or incorrect overlaps can reduce wind and water resistance.
• Rushing through the flashing details: These small components do the heavy lifting for waterproofing; give them the attention they deserve.

Conclusion: Why Onduline Over-Roofing Is a Game-Changer?

Over-roofing with Onduline is more than just adding a new layer of roofing tiles – it’s a complete upgrade in efficiency, aesthetics and sustainability. From our recyclable materials and lightweight panels to our user-friendly installation system; every aspect of Onduline over-roofing is designed with performance and convenience in mind. Our solutions are built to last and offer

• Less mess
• Lower costs
• Minimal disruption
• Maximum durability and appeal

Ready to give your existing roof a fresh start? Explore Onduline’s range of over-roofing solutions and get expert support, because with Onduline, you don’t just build roofs – you build trust.