22 Aug GRP or thermoplastic composite door skins?

GRP or thermoplastic skins are the two most common options for composite doors in Cardiff. The skin is the first thing that stands between your home and the rain, wind, hot sun, and everyday wear and tear. It is also one of the biggest things that decides how well your door will retain heat and how long it will keep working before it needs replacing.

At Affordable Quality Windows, the GRP skin is used in the Universal composite range. The thermoplastic skin is what you will find in the Palladio monocoque range. They each have their benefits, so it is really about what you need most.

What is a GRP door skin?

GRP, also called fibreglass, is made by mixing glass fibres with resin and moulding it into a hard outer shell. In the Universal range, this shell is compression-moulded for a deep woodgrain look.

The GRP skin is attached to a foam core, which keeps the weight down and improves insulation. It does not soak up water, will not rust or rot, and has a UV gel coat to reduce fading. Because of the glass fibres, the skin can also handle knocks without easily getting damaged.

The skin itself is about 2 mm thick over the foam core. Doors of this type usually have a U-value around 1.4 W/m²K.

What is a thermoplastic door skin?

Thermoplastic skins are made from strong uPVC sheets that are shaped and bonded to the door structure. In the Palladio range, they are part of a solid 65 mm monocoque slab.

The skin is built into a single fibreglass-reinforced shell, not just layered over foam. This makes it very impact-resistant and fully waterproof. The colour and finish are also part of the material, so they don’t fade easily.

The solid build stops warping and keeps the seals tight, so no draughts can get through. Palladio doors can have U-values as low as 0.205 W/m²K for the door leaf and about 0.85–0.98 W/m²K for the full door, which is excellent for insulation.

Which is better?

Both GRP and thermoplastic will keep the rain out. The difference is that thermoplastic on a solid monocoque shell tends to keep its shape better over many years. That helps the seals stay tight and keeps heat from escaping. Thermoplastic also insulates more, which can mean lower heating costs in the long run.

GRP has a gel coat that effectively hides small scratches. Thermoplastic depends on its hardness and the fact that the colour runs through the material.

GRP gives you a deep woodgrain look that feels close to real timber. Palladio’s thermoplastic skins also look like wood but have a more solid feel when you touch them. The thick, solid monocoque design behind thermoplastic skins also gives better resistance to forced entry than GRP doors with a foam core.

Are you looking for high-quality composite doors in Cardiff?

At Affordable Quality Windows, we supply and install GRP and Palladio thermoplastic composite doors in Cardiff. Our team can help you compare styles, colours, glazing, and hardware so you get the perfect door for your home and budget. Contact us today to request a free quote or book a survey.