Generally, in the UK, double glazed windows are somewhere between 20mm-24mm, but sometimes up to 28mm. However, the optimum thickness for thermal insulation is 24mm.
Quality PVC-U Windows, Doors and Conservatories We Put Our Names To
Generally, in the UK, double glazed windows are somewhere between 20mm-24mm, but sometimes up to 28mm. However, the optimum thickness for thermal insulation is 24mm.