Waterproofing Concrete Roof Working Surface 1

[humanengr]

I have a building that requires a concrete roof to allow access to machinery on the roof.
The roof will be used to support equipment and parts as well as hand trolleys or light fork-lift. The roof will also have lay-down areas for placement of machinery parts, etc.
Question: What type of water-proofing is suitable for the concrete roof that will be durable enough to withstand the wear and tear of traffic, machinery and heavy parts on the roof?
Any ideas or experience you can share on this would be appreciated.

 

[BAretired]

Maybe the waterproofing should be placed first, then the concrete slab on top.

BA

 

[hokie66]

Maybe you can tell us more about the building, including the plan size of this trafficable roof area, and also what the area below is used for. For a relatively small area, you may be able to use a heavily reinforced cast in place slab, or possibly a post-tensioned slab, with perhaps a liquid applied trafficable surface. For larger areas, the slab would need to be first waterproofed on the top surface, then a drainage layer and topping slab placed. But acceptable solutions vary a lot with where you are located in the world...a concrete rooftop carpark over a shopping centre in Australia would be done differently than for a facility in North America where ice and snow conditions prevail.

 

[humanengr]

There are two roof segments, each at a different elevations. Each segment is approx. 26 ft. wide x 82 ft. long. The building is an un-air conditioned industrial housing equipmet. The location is a high wind reqion (110 mph) and moderate seismicity. Zero Snow load.
Besides protecting the inside of the building from water infiltration I want to protect the concrete roof slab to avoid water seepage and resulting corrosion.
I'm thinking of using brushed concrete surface and a paint-on / roll-on liquid sealant. Roof will probably have 1% slope for drainage.

 

[hokie66]

That may or may not work. If there is enough reinforcement in the slab (approximately 0.6% Ag), the width of cracks should be limited enough so that water penetration is prevented. It also depends on how the slab is restrained. Another solution is to batten the roof and use metal roofing. At that slope, you would need a concealed fastener type metal roofing system.

 

[JLNJ]

For not-so-waterproof slabs we have used fluid-applied membranes or concrete additives.

If you want a roof, do what BA says and utilize a double slab with a proper membrane between. The only times I have done this is where the basement of a building extends beyond the exterior wall line. Not really a great idea in the first place, but that never stopped an architect.

 

[concretemasonry]

How about a concrete roof system that is waterproofed. Then XPS foam, some sand and then gravel with 2'x2' (or so) used for access paths to frequently used items (AC,filters, etc.). Wood runners and platforms can be moved for additional access on an as-needed basis.

I have seen the same with the waterproofing systems and the foam reversed to keep the controlled envelope tied to the more stable interior temperatures.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.