I found an interesting read at this website (click our headline to read all of it) from a commercial building inspector, he basically affirms my statements about decks, leaks, drains/scuppers and railings…
Exterior doors vary from the usual metal frame and glass entry doors to metal roll up doors for loading and unloading and metal pedestrian fire escape/exit doors. In my experience, exterior door thresholds, that portion on the flooring that you step across when you walk through a door, are the main source of water intrusion at doors.
A problem with thresholds usually occurs when they are level with the exterior. This is often a source of moisture intrusion. The industry standard is that the threshold is to be above the exterior level by at least 1.5 inches. This is to allow for a proper moisture barrier. Rarely is this the case.
Exterior decks can be of many types. Tile, stone, waterproof material, concrete and metal are the most common for a commercial building. My biggest issue with decks is the waterproofing, especially if it is over occupied space. I look very closely at the transitions such as connections to the building and railings with special attention to the door thresholds. These areas usually require regular maintenance such as resealing the waterproof decking surface every 3 to 5 years depending on the material and foot traffic. In a very heavy traffic area this may need to be done more often.
Another area I pay particular attention to is the drainage. This can be an issue with enclosed decks with surface drains. Enclosed decks are the decks with solid walls for railings. The only place water can get out is through surface drains. If any leaves or debris get on these drains this can create a dam in a very short time during a heavy rain. These drains can clog up very easily and the deck can quickly become a tub. I really try to make sure the interested parties understand how important it is to keep these drains free flowing and to maintain them. I speak here from hard won experience.
In my experience, railings around decks generally have two main areas of concern. One is the height. Some of the very old deck rails dont feel safe specifically, any railing type or style that is less than 36 inches tall. The other is spacing. The City of Los Angeles recommends that the spacing between rails be no wider than 4 inches. The other possible issues are rusted, damaged or loose railings.
See their website at http://www.commercialrealestateinspectors.com