I work in the upvc windows and doors industry and recently was visiting our friends new house. I was surprised to find a huge drop to her decking area from her outward opening french doors, about 300mm from the top of the threshold. I told her to get on to the housebuilder and get them to raise the decking as it didn't comply with building regs, but the company assured her that the height is fine. I have trawled the internet and cannot find a maximum height for this, can anyone help?