Thread: Residential Code Question

Are contraction (control) joints required by code for slab on grade construction?

Thanks

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Originally Posted by esmeyers

Are contraction (control) joints required by code for slab on grade construction?

Thanks

ESMeyers,

I do not recall any. Most likely, that would be covered in the specifications or details in the construction documents (building plans).

Originally Posted by Gunnar Alquist

ESMeyers,

I do not recall any. Most likely, that would be covered in the specifications or details in the construction documents (building plans).

Gunnar, thanks for answering my question. I guess I need to get my hands on the construction documents. Also, the other houses in the neighborhood of similar design have these joints placed at the designed specifications.

Everything I've read up to this point says they should be used for this type of foundation. Please see the following:

Building code requirements for structural concrete (ACI 318-08) and commentary

By ACI Committee 318, American Concrete Institute, International Organization for Standardization

Building code requirements for structural concrete (ACI 318-08) and commentary - ACI Committee 318, American Concrete Institute, International Organization for Standardization - Google Books

Page 318-370 Section 22.3 Joints

"Contraction or isolation joints shall be provided to divide structural plain concrete members into flexurally discontinuous elements.The size of each element shall be chosen to limit stress caused by restraint to movements from creep, shrinkage, and temperature effects."

And so it clearly states in the code for structural concrete requirements that they are needed in certain situations. There may be some wiggle room in the section just after in Commentary R22.2 Limitations. Not sure here, just looking.

Thanks for your time.

Everyone talks about joints. If there's a site out there talking about the construction of slabs, you can be sure they will emphasize using joints in the construction.

How to Build High Quality Slabs on Grade - The Concrete Network

joints in Concrete Slabs