Expansion joint in cellar floor 1

[Robert-32]

What is the maximum allowable length of a cellar floor without an expansion joint?

 

[jayrod12]

For a single family residence?

I assume it's just a slab-on-grade? If so, we never put joints in those. The randomized cracking that develops is usually acceptable in a cellar/basement.

 

[Robert-32]

It a big reinforced concrete building with floor area of about 2000m2.

 

[phamENG]

It all depends on the construction. Is it a non-structural slab on grade? Is it a structural mat foundation? Will the seasonal water table ever be above the elevation of the slab? Lots of things to consider.

Each one (or combination of variables) may result in a different answer.

 

[Robert-32]

It is a basement floor with mat on piles foundation, 6.5 h retaining basement walls, and flat slab with drop panels. Water table is not present, but surface water might flood the area.

 

[phamENG]

Did you try calculating the stresses your concerned about to see how often you need to break up your building to relieve them?

 

[Robert-32]

I did for another projects, but for this one I believe the answer should be clear in some code.

 

[phamENG]

Codes don't design buildings, engineers do. For a retaining wall or slab on grade, sure, there are some good rules of thumb. And there are some for building expansion joints, too. But even with those, the answer will be vastly different between a 5m x 400m and a 45m x45m building.

 

[Robert-32]

What about 70x29m?

 

[JLNJ]

Concrete usually doesn't expand. Why do you think you need an expansion joint?

 

[Robert-32]

JLNJ, Concrete expands and contracts.

 

[GeorgeTheCivilEngineer]

Basements will have near constant thermal conditions so I'd be prepared to stretch the upper limits. For most buildings this would mean no movement joint.

 

[Robert-32]

You are right George, but I am thinking of the constitution phase that takes several months.

 

[Tmoose]

My basement is L shaped.
We put strips leading out from the inside corner in both directions.
I would have put strips every 25 or 30 or so feet even if it was a simple rectangle.

Also steel mesh, and a full poly film vapor barrier on grade before pouring.