Composite Glass Reinforced Polymer (GRP) Doors are the closest you get to the appearance of a timber door without the need for the maintenance associated with timber products. When you choose a Composite Door, you will get the performance to ensure a long, trouble-free life. Portcullis Home Improvements’ quality Composite Doors are engineered to be dimensionally stable, putting an end to winter expansion and summer contraction. They will not warp, bow, crack or swell thanks to their quality method of construction, which also ensures minimal maintenance requirements.