Durability of Non-Structural Topping Slab in Cold Climate
Durability of Non-Structural Topping Slab in Cold Climate
(OP)
A client has specified the following for a non-structural patio topping slab:
1) Concrete thickness = 2"
2) Reinforcement = none
3) Air = 5-8%
4) Climate = bloody cold
How would you feel about this from a durability perspective? What is the minimum thickness / reinforcing that you would accept for such an element?
1) Concrete thickness = 2"
2) Reinforcement = none
3) Air = 5-8%
4) Climate = bloody cold
How would you feel about this from a durability perspective? What is the minimum thickness / reinforcing that you would accept for such an element?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.






RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
So you like 4" w/18" o/c? I thought XR was being a bit facetious.
I've done a few 1.5-2.0" toppings on above grade wood decks that seem to have fared alright. I dislike durability stuff. There never seems to be any equations yielding binary pass/fail results.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Durability of Non-Structural Topping Slab in Cold Climate
But I think we were both being facetious. I'd have to see what we've done for exterior topping slabs.
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
I'm assuming this slab will be cast during non bloody cold conditions.
RE: Durability of Non-Structural Topping Slab in Cold Climate
I've been torn about whether or not to include reinforcement in a 2" topping as well. On the one hand, it would provide some degree of crack control. On the other, it's steel subject to corrosion in a setup where cover will be inadequate. I suppose that one could use some manner of reinforcement other than steel.
One important feature that I should have mentioned is that the topping slab is seperated from the main, structural slab by a layer of insulation and waterproofing membrane.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
Good point Teguci. Can you comment on what a suitable slip plane construction might be? In this particular case, the affected areas are pretty small in plan.
Gravels and sands, no swelling potential. This is, however, a suspended slab condition.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
Initial shrinkage and thermal movements are helped greatly with a slip sheet/visqueen layer below the floating slab...it will crack though without some amount of control jointing (not to mention when someone drops their bowling ball on it).
Cannot recall absolute specifics, but in a similar situation where this was our baby to deal with: we had 3 or 4" floating/plaza slab with welded-wire fabric reinforcing, and tooled joints at something like 4' or 6' o/c. Low W/C ratio (Chicago - heavy de-icing salt use) Went with tooled joints, and they are a lot nicer looking than saw cuts. Final product looked nice with only a couple of corner cracks on something like 20-25 patios. I never heard of any issues in the years since.
...FWIW, I would be raising the same concerns if I was the contractor. If the architect asks your opinion on the record, I recommend you get on record noting that some measures could be made to improve durability and life of his overlay.
RE: Durability of Non-Structural Topping Slab in Cold Climate
RE: Durability of Non-Structural Topping Slab in Cold Climate
I like it. How would we feel about a 3" topping with galvanized WWF at mid-depth?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.