Building Waterproof Balcony Deck in Florida

by Bob
(Coco Beach, FL)

I am rebuilding a second floor balcony that exists above a backyard patio. This time I want it water tight as I have gotten very tired of the frequent Florida rains dripping through getting everything wet and soiled. Besides, I expect to eventually screen this area of the patio below. The house is a rather simple Mediterranean style with red tile roof and brown painted rough-cut cedar fascia boards and soffits.

The balcony is built on 6 cantilevered built-up PT beams extending 7’ out from the center of the concrete block house. I intend to extend the deck’s depth to 11 feet using additional support from new posts positioned along the perimeter of the patio below. I’ve already built the patio up a few inches (for better drainage) and added a short (20”high) rebar reinforced concrete wall on two sides with embedded 316 stainless 5/8” J-bolts for fastening the post supports. But I lack a clear idea of how to construct the actual balcony.

Another thought is that the structure design ought to support the addition of some sort of covering for the balcony in the future. So maybe the posts should penetrate the deck for strength and rigidity. But I dread waterproofing the post penetrations, and can’t visualize what it’d look like. I lean toward using dock-rated PT YP for structural strength and longevity, and facing it with 1-by western cedar rough side exposed.

I’ve “Googled” for hours at a time for at least a week without finding ideas from experts on how to approach construction of a water tight deck. And I spent all yesterday browsing through books and magazines in the library and in a local mall – found nothing useful.

Can you offer direction?

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Editor's Comments:

There are a number of ways to waterproof a balcony like yours such as: interlocking water tight decking, vinyl decking flooring membrane, under-deck drainage systems to name a few.

However all of these require some work to do properly and to be sure that the ledger connection between the balcony and the house is properly mechanically flashed. This requires a lot of work and much be done precisely.

The vinyl membrane flooring option would use something like a duradeck or weather deck system. All proven and the installations are guaranteed if installed by their professionals.