Flat roofs with easy access are great for creating an outdoor living space. The best way is to construct a sleeper deck.
A sleeper deck is simply a deck that is not attached to anything. The weight of the deck is what keeps it on the roof. Also, any handrails or posts for the deck are attached to the sleeper deck frame so that no penetrations go through the roof surface.
Prior to installing a sleeper deck, the roof should be inspected by a roofing contractor to ensure that the roof is in good enough shape to allow for a deck.
The deck frame is assembled so that the deck surface is level. This requires some shimming of the deck that is typically done using foam board insulation that will not harm the roof surface. Any framing toughing the deck is wrapped in either roofing felt or synthetic felt to prevent roof surface damage and protect against moisture on the deck framing. The posts for the deck can be mounted directly to the deck framing using lag bolts so that the railings will be stable enough to act as proper fall protection.
The deck surface should be installed so that proper ventilation and drainage can occur. Gapping the deck boards a minimal of 1/4" is necessary to prevent pooling water on the deck surface and top allow for air to dry the water that does not drain of the roof surface underneath. Either treated wood, cedar, teak, or redwood should be used for deck surfaces if natural wood is desired. Otherwise composite deck boards allow for maintenance free deck treatments.
The railings have to have vertical spacing no more than 4" wide. The railing height depends on the building code for that area but typically ranges from 36" to 42." Railings and guard rails can also be made of panels. Glass is a great option for unobstructed views and there are many style to choose from.
Creating outdoor space is great way to increase square footage and increase property value. If you have a flat roof that is not being utilized and is easily accessible, this may be a great solution for your home.