Converting existing interior slab to exterior balcony
Converting existing interior slab to exterior balcony
(OP)
A building owner wants to explore creating balconies by removing the exterior cladding and re-cladding the facade about 10' inside the building perimeter. This would convert what was an interior slab to an exterior slab exposed to the elements. Columns are on the exterior, so the balconies would not be cantilevers.
My main concerns are not having enough concrete cover for an exterior condition, and freeze-thaw cycles (this is a moderate climate with annual freezes). The best I have come up with so far is a bonded topping slab with a "traffic coating" to provide cover and waterproofing, and some sort of liquid waterproofing membrane on the underside of the slab (since the bottom bars will be critical to the structure).
I saw in the other balcony thread that some engineers are using 3/4" cover with a protective membrane for balconies. I don't think I would do this for a new design, but for a retro-fit like this, it may help with the code requirements since it will be difficult to retroactively add cover.
My main concerns are not having enough concrete cover for an exterior condition, and freeze-thaw cycles (this is a moderate climate with annual freezes). The best I have come up with so far is a bonded topping slab with a "traffic coating" to provide cover and waterproofing, and some sort of liquid waterproofing membrane on the underside of the slab (since the bottom bars will be critical to the structure).
I saw in the other balcony thread that some engineers are using 3/4" cover with a protective membrane for balconies. I don't think I would do this for a new design, but for a retro-fit like this, it may help with the code requirements since it will be difficult to retroactively add cover.






RE: Converting existing interior slab to exterior balcony
Thaidavid
RE: Converting existing interior slab to exterior balcony
RE: Converting existing interior slab to exterior balcony
RE: Converting existing interior slab to exterior balcony
Waterproofing the soffit of the slab is not a good idea, as that prevents water from escaping, not what you want.
RE: Converting existing interior slab to exterior balcony
Also, concrete quality will determine how durable this ends up being. For instance, if the slab is hard troweled, you may have a problem with freeze-thaw durability.