Sterling Doors
Sterling Doors

Technical Information


Every Water Max GRP composite door is manufactured to the highest of standards to ensure it is strong, durable and secure. We have sold over two million doors to date, evidence of thequality and exacting specification we demand.

The door has a perimeter sub-frame of a solid, water-resistant polymer material, which is reinforced with Laminated Veneered Lumber (LVL). A thermoset GRP skin is bonded to this sub-frame and the core of the door is then filled with high density, 100% CFC-free polyurethane foam. Finally, water resistant polymer composite rails protect the core from damage or water absorption.

The door’s core is what makes it so thermally efficient and so good at reducing sound. In fact, as you can see from the imageson page 6, it is the most thermally efficient door on the market, increasing your home’s energy efficiency and saving you money on your energy bills.

The high impact resistant thermoset GRP skin not only keeps your door looking good, it will not expand and contract laterally so your door will not crack or delaminate. All standard solid colours are pre- pigmented and beautifully through-coloured. All other colours are oversprayed with a durable paint that will not peel or crack.

Technical Figures

A Water Max GRP composite door has a wealth of facts and figures that prove its quality:

  • achieves BS 6375-1 for weather tightness, air, wind and water
  • achieves PAS 24 security standard, a prerequisite for achieving Secured by Design status
  • reduces outdoor noise by an average of 31dB
  • achieves Global Warming Potential (GWP) score of less than 5
  • achieves Ozone Depletion Potential (ODP) score of zero
  • meets UK Building Regulations U value requirements of 1.6 W/M 2 K

In other words, everything about a Water Max GRP composite door has been designed to enhance your home for years to come.

Care and Maintenance

Your Water Max GRP composite door has been designed to be easy to maintain. To keep your door clean, prolong the life of the surface finish and protect your warranty, we recommend you wash it regularly using warm soapy water (washing up liquid is ideal) and a soft, lint-free cloth. If you live in a coastal area, in a heavily industrialised area or near a main road, you may need to clean your door more frequently.

It is important that you DO NOT use any of the following on your door

  • abrasive cleaners or scouring pads
  • any type of bleach or solvent (e.g. white spirit, methylated spirit, cellulose thinners, acetone or nail varnish remover)
  • any type of adhesives or tack for providing temporary protection or fixing of seasonal or other decorations etc
  • high pressure or steam cleaners.