How to Seal Corrugated Fiberglass Panels

Written by jane humphries
  • Share
  • Tweet
  • Share
  • Pin
  • Email
How to Seal Corrugated Fiberglass Panels
Corrugated fibreglass requires a top coat to seal the resin from deterioration. (corrugated panels image by Christopher Dodge from

Corrugated fibreglass panels are strong mould-resistant sheets commonly used for exterior roofing, outbuilding doors and siding. Over time the glazed pigmented seal applied during the manufacturing process can crack causing the structural breakdown of fibreglass resin by weathering. It is important to know how to seal corrugated fibreglass panels using the correct products to provide durable adhesion. Applying the seal uses a similar procedure to all exterior material types except that the sealing product constitute is critical for fibreglass.

Skill level:

Other People Are Reading

Things you need

  • Cloth
  • Water-based degreaser
  • Jetwash
  • 80-grit sandpaper
  • Hand brush
  • Stir-stick
  • Latex acrylic primer
  • Paintbrush
  • 400-grit sandpaper
  • 100-percent acrylic paint
  • Respirator
  • Rubber gloves

Show MoreHide


  1. 1

    Wash the corrugated fibreglass panels with a cloth and a water-based degreaser to remove dirt. Use a medium pressure jetwash to quickly remove flaking paint or gel coat. Allow the panels to dry.

  2. 2

    Use 80-grit sandpaper to rub the fibreglass surface in order to create a mechanical bond for the sealing primer. Sweep away the sanding dust on the panel using a hand brush.

  3. 3

    Use a stir-stick to mix the latex acrylic primer to an even consistency. Choose a paintbrush width that matches the width of a rib on the panel so that the primer is easier to apply in the "V" of the corrugation. Brush the primer evenly onto the fibreglass surface and allow it to dry.

  4. 4

    Sand the latex acrylic primer with 400-grit sandpaper to lightly abrade the sealed surface. Sweep off any sanding dust from the fibreglass.

  5. 5

    Stir the 100 per cent acrylic paint until the mixture is a uniform colour. Apply a coat of paint over the primer using a paintbrush. Allow the paint to dry and lightly sand the surface as you did in Step 4.

  6. 6

    Apply a final coat of acrylic paint over the first coat to complete the corrugated fibreglass panel sealing procedure. Allow the paint to dry and cure according to the manufacturer's instructions before applying any pressure to the panel.

Tips and warnings

  • Use a scrubbing brush and water as an alternate to a jetwash.
  • Wear a respirator and rubber gloves when sanding the fibreglass to avoid contact irritation from the fibre particles.

Don't Miss

  • All types
  • Articles
  • Slideshows
  • Videos
  • Most relevant
  • Most popular
  • Most recent

No articles available

No slideshows available

No videos available

By using the site, you consent to the use of cookies. For more information, please see our Cookie policy.