When installing corrugated plastic roofing sheets, the sheets themselves are only part of the system. To achieve a weatherproof, long-lasting, and professional finish, it’s essential to use the correct roofing accessories. Fixings, fillers, and flashings all play a vital role in protecting your structure from leaks, wind uplift, and long-term wear.
In this guide, we’ll explain what each accessory does, why it’s important, and how to use it correctly when installing corrugated plastic roofing.
Why Roofing Accessories Matter
Even the highest-quality corrugated plastic sheets can fail if installed without the proper accessories. Correctly selected and fitted accessories:
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Prevent water ingress
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Improve structural stability
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Extend the lifespan of your roof
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Enhance the finished appearance
Using compatible accessories ensures your roofing system performs as intended in all weather conditions.
Fixings: Securing Your Corrugated Plastic Sheets
What Are Roofing Fixings?
Fixings are specially designed screws or nails used to secure corrugated plastic sheets to timber or metal roof supports. They typically include a rubber or plastic washer to create a watertight seal.
Why Correct Fixings Are Important
Using the wrong fixings can cause:
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Cracking around fixing points
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Leaks due to poor sealing
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Sheet movement in strong winds
Purpose-made fixings allow for thermal expansion while keeping the sheet firmly in place.
How to Use Fixings Correctly
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Fix through the crest of the corrugation, not the valley
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Avoid over-tightening
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Use the recommended spacing between fixings
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Always use washers for a watertight seal
Fillers: Sealing the Gaps
What Are Corrugated Roofing Fillers?
Fillers are shaped foam or plastic strips that match the corrugated profile of your roofing sheets. They’re installed at the eaves and ridge to block gaps between the sheets and the roof structure.
Benefits of Using Fillers
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Prevent rain, snow, and wind-driven moisture entering
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Stop insects, birds, and debris
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Improve insulation and airflow control
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Enhance roof durability
Where Fillers Are Used
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Eaves fillers: At the bottom edge of the roof
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Ridge fillers: Under ridge caps
Using fillers is especially important in exposed locations.
Flashings: Weatherproofing Roof Edges and Junctions
What Are Roof Flashings?
Flashings are protective strips used where roofing sheets meet walls, edges, or roof transitions. Common types include:
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Wall flashings
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Aprons
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Verge trims
Why Flashings Are Essential
Flashings prevent water from penetrating vulnerable areas, such as:
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Roof-to-wall junctions
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Open roof edges
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Overlaps and transitions
Without flashings, water can track behind sheets and cause leaks or structural damage.
Choosing the Right Accessories
To ensure long-term performance:
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Use accessories designed specifically for corrugated plastic sheets
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Match the profile and size of your sheets
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Choose UV-resistant materials for outdoor use
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Avoid mixing incompatible brands or materials
Correct compatibility ensures a secure, leak-free roof.
Common Installation Mistakes to Avoid
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Skipping fillers to save time or cost
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Using standard screws instead of roofing fixings
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Over-tightening fixings
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Failing to install flashings at wall junctions
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Incorrect sheet overlap
These mistakes can significantly reduce the lifespan of your roofing system.
Final Thoughts
Corrugated plastic roofing accessories are just as important as the sheets themselves. Fixings secure the roof, fillers seal gaps, and flashings protect vulnerable areas, working together to create a durable, weatherproof roofing solution.
By using the correct accessories and installing them properly, you’ll ensure your corrugated plastic roof performs reliably for many years—protecting sheds, greenhouses, carports, and garden buildings with confidence.
