Steel frame deck around a pool

[palmettoinspect]

I've come across these steel framed and concrete/stone decks on a few houses used around a swimming pools. Some do okay, some exhibited terrible failure after about 20 years from the pool and rain water deteriorating the steel "I" beams.

I came across another one yesterday about 10 years old that isn't as bad, but eventually the steel "I" beams will deteriorate. This just seems like a poorly thought-out design for an open air deck around a pool. I know you can water proof these concrete and steel decks, but this one wasn't. Constant watering of the planter boxes, rain and pool water are clearly leaking through to the steel. 

My questions is if these decks are designed without water proofing, what would be the life expectancy of the steel framing and what preventative measures can be taken to help slow the rust and deterioration? Painting the steel seems like a never ending task. At what point is it considered normal and what point is it a mess?

Edited December 7, 2017 by palmettoinspect

[mjr6550]

I can't tell from the photos whether there are drainage slots in the steel deck pan. I see something, but that may be dimples to create composite action with the concrete. The few cases where I have seen concrete on deck pan exposed to the whether they have not looked good. Seams like it is easy for water to get in and no so easy to get out.

The corrosion at what I assume is the house foundation wall suggests that the deck is not well sealed at the house or does not slope properly. I,m not sure how successful it would be to seal the surface. Maybe a high solids Silane or Siloxane would help. I think there may be a more suitable product for horizontal surfaces, but can't recall now.

From the look of those I-beams they may be around far longer than the patio. It could take 30 to 50 years (possibly less) for corrosion to be a structural concern, but rust jacking could cause some damage to the patio. 

BTW, what is the point of this anyway. High water table? 

[Jim Katen]

Are those just functioning as forms or are they supposed to be providing support to the concrete? 

[mjr6550]

Looks like structural deck pan designed to bond with the concrete and serve as tension reinforcement (in place of rebar).