Materials · Detail
Polyester dormer
Polyester, or GRP, is a strong and lightweight composite used for some prefab dormers. It is durable, mouldable and low maintenance.
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Short answer
A polyester dormer is made from glass-reinforced plastic (GRP). It is strong, lightweight, rot-proof and often used for prefab units or custom shapes. It is more durable than basic PVC but usually costs more.
What is polyester?
In this context, polyester means glass-reinforced polyester (GRP) — a composite made by embedding glass fibres in a polyester resin. The result is a tough, mouldable shell that can be made in almost any shape.
Pros and cons
- Pros — strong, lightweight, rot-proof, corrosion-resistant, mouldable into complex shapes, low maintenance.
- Cons — can be more expensive than PVC, colour choices may be limited, surface can fade if not UV-stabilised.
Comparison
| Factor | Polyester (GRP) | PVC | Timber |
|---|---|---|---|
| Strength | High | Moderate | High |
| Weight | Light | Very light | Heavy |
| Maintenance | Low | Very low | High |
| Shape options | Excellent | Limited | Good |
| Cost | Mid to high | Lower | Higher |
The full checklist
Checklist
Polyester dormer checklist
- 01The product is UV-stabilised to prevent fading.
- 02Wall thickness and reinforcement are specified.
- 03Colour and finish are chosen for the house style.
- 04Window and door cutouts are properly finished.
- 05Junctions and flashings are designed for the material.
- 06Warranty covers the shell and finish.
FAQ
FAQ
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01What is a polyester dormer?
A polyester dormer has a shell made from glass-reinforced polyester (GRP), a strong, lightweight plastic composite. It is often used for prefab dormers and special shapes.
02Is polyester durable?
Yes, GRP is very durable, weather-resistant and can last 30+ years. It is not affected by rot or corrosion.
03Can a polyester dormer be any shape?
GRP can be moulded into complex shapes, which makes it useful for bespoke designs, curved roofs and small-batch production.
04Is polyester heavier than PVC?
Polyester is generally heavier and stronger than PVC. It is closer to a composite in weight and rigidity.
Conclusie
Polyester dormers are a good choice when you need strength, low maintenance and the freedom to create a custom shape. Compare them against PVC and timber on price and appearance.