Flooor drain location

[Reit38]

Planning on pouring a 18ft wide slab in my shop soon. Trying to figure out where I'm putting my floor drain. I planned on cutting at 9ft. Will having a drain on the edge of my cut effect anything or would i ne better kff centering the drain on the cut line.... assuming I also still need to cut at the four corners for the slope either way. Crude drawing but aimilar to this

 

[Leaflessshadetree]

Why would you cut the corners (diagonals)? I try to avoid triangles with concrete, it is fairly common to crack near the points.

 

[The Cobbler]

90° inside corners are prone to crack, too

I try to avoid triangles with concrete, it is fairly common to crack near the points.

 

[Reit38]

Why would you cut the corners (diagonals)? I try to avoid triangles with concrete, it is fairly common to crack near the points.

Not sure. Our work has corners cut by their floor drains, have forktrucks driving over them with no issues.

 

[ConCretin]

Use a round drain body and you eliminate any issues with shrinkage cracks caused bu re-entrant corners. Make a single control joint cut in each direction and you should be fine. I'd plan for a minimum of 1/8" per foot pitch and as much as 1/4" per foot if you really want to minimize birdbaths. It seems obvious but make sure you grade your base to mirror the slab pitch to maintain a consistent slab thickness.

If you are set on a square drain body, just do the diagonal cuts to the corners. The square penetration will concentrate shrinkage stress and cause cracks diagonally from some or all of the corners. The control joints won't prevent cracks, they will just hide them.

 

[scooby074]

Why not slope it down towards the garage door on a single plane and put a trench drain there?

 

[Stuart in MN]

Why not slope it down towards the garage door on a single plane and put a trench drain there?

A friend of mine recently built a garage with a trench drain in front of the garage door, it seemed like a pretty good solution to me.

 

[Joemctag]

90° inside corners are prone to crack, too

Agree, but you can reinforce those inside 90s at the drain with mesh. Rebar too close to an edge, or top or bottom, of a slab, can cause cracking. Use mesh. Or round drain.
Are you not going to have sawcuts both sideways and up and down, per your drawing? The idea is that dividing into squares is ideal.
ConCretin knows what he’s talking about.

 

[roger55]

I recently bought a new house that came with a 3200 sqft detached workshop. The front section has a drain in the floor and the whole front half of the floor slopes to the drain and the rear half of the floor is perfectly flat. I don't know how they did the drain but I think there is a gravel pit that allows the water to escape and a line higher up in the pit that will accept water if the pit can't disperse it fast enough. That's just my guess though. I am going to try and talk to the previous owner who had this shop built and find out for sure.
The floor has no cracks. The expansion joints have done their job well. This workshop was built in 2011.

 

[Reit38]

Agree, but you can reinforce those inside 90s at the drain with mesh. Rebar too close to an edge, or top or bottom, of a slab, can cause cracking. Use mesh. Or round drain.
Are you not going to have sawcuts both sideways and up and down, per your drawing? The idea is that dividing into squares is ideal.
ConCretin knows what he’s talking about.

Sorry wasn't clear this will be 18x40 total pour so that picture would actually be an 18x10ft section

 

[ConCretin]

Rebar or mesh don't prevent cracking. Control joints just hide the cracks. The location and construction of the control joints determines whether they are effective at preventing visible cracks.

For a typical 18x40 slab, I'd cut one longitudinal joint and three joints across resulting in four 9x10 panels. if you have a contractor that knows what he is doing, you could cut a single transverse joint resulting in two 18 x 20 panels.