Showing Thickened Slabs under Partitions

[MattJM]

I am wondering what the industry practice is for showing (or dimensioning) thickened slabs under interior CMU partitions.

My opinion is that if I need it structurally (I am assuming I do if I want to spend the money to build it) then I should show it structurally on plan.

A typical detail might do the job, but I wouldn't handle another footing in this way. I'd show it on a plan if I could, dimensioned if I could.

The other side of this coin, as my co-worker suggests: The architect may move these partitions around. This is a recipe for uncoordinated or incorrect documents. "See arch" notes might help, but better not to show them on plan. Let the typ detail govern.

Middle ground: show something, with "see arch" notes, but do not dimension. Verify at shop drawing time.

I can see validity on all sides of this. The final point is that the direction of the office is: "show things that are correct, don't show things that are incorrect, don't miss things that should be shown, and don't show things that are likely to change." That is not too helpful.

What would you show? What is standard?

PS. Does the answer have a similar application to slab depressions?

 

[MiketheEngineer]

I show them on the foundation/footing plans all the time. Usually something like 18'' wide by 12'' deep - depends on loads.

Sure - people move walls in the future - but you have no control if/when/how they do that. They could also take out the front wall in the future - now what??

 

[charliealphabravo]

I like the idea of having a general note on the foundation plan that directs the contractor to the typical detail for non-bearing partitions. This way the job is done. If the architects interior layout changes a dozen times or at the last minute you will not be the hold up and the foundation plan does not need to be revised.

Pluses and minuses all around I suppose.

 

[msquared48]

Kinda hard to get 3" of clearance to the soil with a 4" slab on a bent #4 stub bar and still have it be effective if you don't have a thickened footing. I always do.

Mike McCann
MMC Engineering

 

[Lion06]

We just have a typical detail and keep an eye out for it in the shop drawing process.

 

[MattJM]

Thanks all! This is about what I thought - mixed bag.

My first mentor 18+ years ago showed everything on plan, dimensioned even if the architect also showed it, like shower depressions. I guess I still think that way.

But I am coming around to the idea letting the typical details and the "see arch" notes govern. Saves time for me, time I don't usually have to waste on rework.

I'm just worried about cutting things out even when I'm "covered" by the notes and details.

On my latest job we are going to have the depressed slabs shown on the typicals only. I may not be the one checking the reinforcing shop drawings, so I think I'll post a big note on the wall reminding our reviewer to "CHECK THE ARCH DRAWINGS FOR CMU WALLS AND SLAB REINF." - just hope it is still up in 3 years.

 

[BAretired]

My preference is to provide a slab adequate to carry the non-bearing masonry partitions without using a slab thickening. That way, the architect can place his walls anywhere he likes. Future changes are not a problem either.

BA

 

[JAE]

I'd go with BAretired's method depending on the number/density of walls compared to other areas of the floor plan where you may not ever have the walls.

Otherwise, I think the best thing is to show them on your plan where the walls are located on the architect's plans (they don't always change that much) but don't dimension them as this forces them to use the architects (latest and greatest) plans to lay them out.

Same thing for floor depressions at thicker tiled floors, etc. - show them but don't dimension them.