Advice For Applying Fibreglass in Winter

Applying fibreglass in winter

Working with fibreglass during winter brings three major challenges: low temperatures, wet weather, and limited daylight. Although these conditions make installation more demanding, applying fibreglass in winter is entirely achievable. With the right preparation and technique, you can still achieve a strong, reliable laminate.

This guide outlines the key steps, temperatures, curing advice, and catalyst mixing ratios to help ensure successful winter fibreglass application.

Key Considerations When Applying Fibreglass in Winter

1. Check Weather and Temperature Before Starting

  • Always review the local weather forecast before beginning any work.
  • Do not start fibreglassing if temperatures are below 5°C, as resin will not cure correctly.
  • Use a catalyst addition chart to determine the correct catalyst percentage for winter conditions

2. Plan Around Limited Daylight

  • Winter curing relies heavily on remaining sunlight and ambient warmth.
  • Avoid applying laminate or topcoat after 2–3 pm, as curing slows significantly once the sun sets.
  • Uncured surfaces are vulnerable to dust, debris, and moisture.

3. Ensure All Materials Are Warm Enough

Check the temperature of:

    • Resin
    • Topcoat
    • Boards and decking surfaces
  • If the environment is below 10°C, store your resin indoors overnight.
    Cold resin becomes thick, difficult to wet out, and may not cure properly.

4. Stop Work Immediately If Rain Begins

If rain starts during application:

  1. Pause all work.
  2. Cover the area with a Visqueen or polyethylene sheet.
    This prevents contamination and protects uncured layers from water damage.

5. Seal the Deck if You Cannot Laminate Immediately

If you install a deck but cannot apply the laminate the same day:

  • Coat the surface with catalysed resin to create a temporary seal.
  • Pay close attention to board edges and exposed areas where moisture can enter.
  • Protect the deck with a Visqueen/PE sheet until you can resume work.

6. Ensure All Surfaces Are Fully Dry Before Laminating

Before laying glass:

  • Remove standing water with a brush or cloth.
  • Allow natural drying time.
  • Speed up drying if needed by wiping with acetone, which evaporates moisture quickly.

7. Expect Thicker Resin and Heavier Application Effort

Cold weather increases resin viscosity.

You may need:

  • Additional effort to wet out the glass
  • Slightly more resin for full saturation

8. Never Fibreglass if Rain is Forecast

Even light rainfall can disrupt curing and damage uncured laminate.
Always work within a clear, dry weather window.

Catalyst Mixing Ratios for Winter Conditions

1gm of catalyst = 1cc

During winter:

  • Using a fast catalyst mix helps offset slower curing times.
  • If required, gently blowing warm air over the surface can help initiate or support curing.
  • For accuracy, consider using a catalyst dispenser, which provides precise measurements—especially useful during cold‑weather mixing.

Winter Fibreglassing: Summary Checklist

 

✔ Check forecast and temperature (avoid <5°C)

✔ Warm resin/topcoat beforehand if ambient temp <10°C

✔ Avoid laminating after 2–3 pm

✔ Stop immediately if it rains and cover the area

✔ Seal exposed decking with catalysed resin if laminating later

✔ Ensure surfaces are fully dry before application

✔ Expect thicker resin and slower curing

✔ Never work if rain is expected

 

REQUEST TECHNICAL INFO

Winter Fibreglassing: FAQ

Can fibreglass be applied in winter?

Yes. Fibreglass can be applied in winter as long as temperatures stay above 5°C, conditions are dry, and the correct catalyst ratio is used.

What is the minimum temperature for fibreglass resin?

Fibreglass resin should not be applied below 5°C, as curing may fail or remain tacky.

Do I need to warm fibreglass resin in cold weather?

Yes. If temperatures are below 10°C, store resin and topcoat indoors to prevent thickening and poor wet‑out.

Why should fibreglassing stop early in winter?

Limited daylight and falling temperatures slow curing. Avoid laminating after 2–3 pm to ensure proper cure before nightfall.

What happens if it rains during fibreglass application?

Stop immediately and cover the area with a Visqueen or polyethylene sheet. Rain can permanently damage uncured fibreglass.

Should catalyst ratios change in winter?

Yes. A faster catalyst mix is recommended in winter to offset slower curing. Always measure accurately using a catalyst chart or dispenser.

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