If you own a commercial building that has businesses that need additional customer seating, some of those businesses might have suggested adding a roof deck. These vantage points offer neat views if the building is in the right place, and the open space on the flat roof can be put to good money-making use. However, adding a deck is not as simple as you think. It can be done in many cases, but you'll have to consider a few issues first.
Excess Weight and Building Structure
The deck material, furniture and fixtures, and the people you expect to be up there will all add weight onto the building. If the building wasn't originally built to hold that much weight, it could cause cracks and contribute to a collapse. You'll have to find the plans to the building (check with your city building code department) and see what the maximum load on the roof and on the frame of the building is supposed to be. If the planned deck and so on will make the building exceed that weight, you'll have to either scale back your plans or avoid building the deck.
Roof Material Integrity
If the weight is fine but the roof is old, you'll have to install a new roof on the building. Shoring up just one area won't do as that can still add stress to the rest of the roof, which, if still old, will not be safe. Another issue is that the roof material you use in the replacement, or the roof material that you already have if the roof is not that old, needs to be something that won't be damaged by all the construction needed to install the deck.
Drainage on the roof may have to be rerouted so that it doesn't flood the deck or damage the supports. That also means potentially changing the locations of downspouts and changing the landscaping around the building to accommodate a new drainage point.
Edge Safety and Access Points
Roofs often have one access point, like a stairwell. If people will be up there constantly, though, you may have to add a second emergency escape route in case the main access point is blocked or too dangerous to use, such as in a fire. You'll also have to add barriers on the edge of the roof that make it difficult for someone to climb over and drop down to the ground.
Talk to roofing contractors, like those from Ray's Harford Home Improvement Contractors Inc, about what it would take to have a successful and safe roof deck added to your property, and whether they could install new roofing material that would resist damage.