There are three main issues when fibreglassing outside during the winter months, cold weather, wet weather and shorter days. Fibreglass work is still possible. With the correct information and a little bit of planning, you can still get the job done.


Apart from wrapping up and braving the elements, follow our simple checklist to get the most from your fibreglass materials.



Our Top Tips for Fibreglass Work in Winter


Always check the local weather forecast; having an app on your phone that you rely on for this is a good idea.


Check the temperature. Do not start fibreglassing if the temperature is below 5°C, as it will not cure. Use the catalyst addition chart to calculate the percentage of resin that should be used.


During the shorter winter days, avoid fibreglass or topcoating a roof after 2-3 pm. The heat from the sun helps the curing process; it is unlikely that it will cure overnight after sunset. This will affect the finish of the topcoat, and debris can stick to the surface of the resin, which will have to be removed.


Check the boards, resin and topcoat temperature before laying the fibreglass. The resin should be left in a warm room the night before using it if the ambient temperature is below 10°C. Care should be taken to ensure that the resin does not freeze.


If it starts raining, stop working immediately and cover the roof with a Visqueen sheet.


If you have a deck laid and are unable to laminate it, coat the decking with catalysed resin to seal it from moisture. Ensure that all exposed edges are covered. Use a Visqueen sheet to cover edges and uncoated boards.


If you cannot laminate over a prepared deck, coat the decking with catalysed resin and cover any exposed edges. This will seal the deck and prevent moisture uptake until the laminate can be applied. Always cover the edges of the roof and uncoated boards with a polyethene sheet.


Always ensure the deck or substrate to be laid onto is completely dry before laying the laminate. Sweep off any excess water and mop up the excess with dry cloths before allowing the roof to dry naturally. Wiping the surface with acetone can speed up this process.


The resin will be thicker in cold weather and will require extra effort to work it into the glass, and more resin may be required.


Do not start to lay a roof if rain is forecasted. 


Cold weather for fibreglass


Catalyst Mixing Ratios for Winter


1gm of catalyst = 1cc

  500g 1kg 2kg 5kg 10kg 15kg
2% (Standard Room Temp Mix) 10cc 20cc 40cc 100cc 200cc 300cc
3% (Fast Winter Mix) 15cc 30cc 60cc 150cc 300cc 450cc


Using a fast mix will help speed up curing times in winter. Blowing warm air onto the area is also possible to help if necessary. If you need help measuring the catalyst, we also offer a catalyst dispenser which will provide an accurate measurement. 


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