Waterproofing Exterior Suspended Slab on Steel Framing

[ekelley]

Is there a need to waterproof an exterior suspended concrete slab on top of steel framing? The architect is requesting a waterproofing membrane and 4" conc topping on top of 6" structural slab to protect structural steel framing below. I have not heard of this as an issue. It changes the design loads on the steel framing significantly. The structural system is a 6" structural slab on steel framing. The floor supports both interior and exterior spaces above although there is a roof above the exterior space. The space below the floor is all exterior, but has a ceiling below bottom of structural steel. Is there a need for waterproofing to protect the steel framing below? Any other options to accomplish this without 4" topping slab?

Thanks

 

[AELLC]

http://www.nrca.net/roofing/Single-ply-membranes-895

The definition of a structural engineer: overdesign by a factor of 1.999, instead of the usual 2.

 

[dik]

It's a really good idea... take a gander at the Algo Centre Mall collapse... I've often used Duradeck type of membrane for walking surfaces for boat houses or a proper EPDM or anyother single ply membrane...

Dik

 

[AELLC]

http://en.wikipedia.org/wiki/Algo_Centre_Mall

I never heard of that one - of course, because for some reason,, all news happening in Canada is suppresses here in the good ole USA>

The definition of a structural engineer: overdesign by a factor of 1.999, instead of the usual 2.

 

[idecharlotte]

I've specified a silicate sealant before such as Concrete Treat for situations like yours to eliminate the need for a topping slab and membrane. It works great. I probably wouldn't use it on an slab without a roof with heated space below but for an elevated garage, or slab without heated space below, absolutely.

http://www.idecharlotte.com

 

[grogannc]

If you use a single ply, I would use densdeck adhered to the structural slab and tapered insulation/blocking if slope is needed. Much lighter than concrete. Single ply roofing directly on concrete wouldn't be my first choice.

 

[JAE]

I would always waterproof it - otherwise you get a rusted mess later on.

We typically use a traffic bearing waterproofing system similar to Pedagard (by Neogard) found here.

Or we use what you describe above as a membrane waterproofing system with a concrete topping/wearing surface.

One we've used in the past is by Carlisle - found here and here

There are other companies for both offering similar products.