Decking and terrace are the two quintessential concepts of a roof terrace, decking refers to the flat surface elevated above normal ground level. It can be built into several types of terrace designs, you can have one in the back of your house, where the elevated position would become very handy if your backyard door is a few feet above the ground. The important factor to consider is the distance between the deck and the backdoor, with London's surly rainy seasons and teeth-chattering winds, you will want to get inside your house as quickly as possible. The terrace is another aspect of roof terrace design, materials such as red pine lumber make it possible to go beyond the plain old concepts of square and rectangle. A professional terrace designer can turn a seemingly plain little space into a sleek, stylish and comfortable room that you might want to live in all year round! When designing a roof terrace it is always important to consider other things as well, such as protection against London's cold and rainy season.
But, you might ask, what if you want to spend London's summer evenings dozing off in a quiet, comfortable place or indulging in the literary feats of Jane Austen? A roof terrace does not have to be about parties or barbeques. In such cases, it is always best to incorporate your lifestyle in the design of the roof terrace because a place for parties might not be the same place for reading books! Roof terraces are extremely flexible in design and concept and hence it is important that you consider why you want one before construction and whether you want it to be an integral part of your lifestyle After all, there is no point of spending all that money on a roof terrace if you are never going to use it!
Source : http://plantingblog.devhub.com/blog/2621705-roof-design-essentials-decking-and-terraces/