control joints on monolithic slab with curb and footer?

[TimberMan]

I have decided to go with a monolithic slab for my 18x24 barn which will have all four sides turned down at least 12" below grade to get get below the frost line and will also have a 6-8" curb all the way around except for the two door openings. Since this will all be one pour and have footings and curb, how are control joints handled?

thx.

 

[Gozo]

Concrete cracks. I’d cut it in quarters. That way you’ll know where the cracks will be. If you leave it as one piece, I’d venture it’ll crack by the footings and a few random places across the middle area.

 

[TimberMan]

Concrete cracks. I’d cut it in quarters. That way you’ll know where the cracks will be. If you leave it as one piece, I’d venture it’ll crack by the footings and a few random places across the middle area.

do i cut into the curb as well?

 

[mike93lx]

@ConCretin

 

[ConCretin]

I agree with Gozo. One control joint in each direction is perfect. The cuts should be 1/4 of the slab depth and be made as soon as possible after finishing. If you have a thickened edge, it's a good idea the cut as deep as you can over these areas.

If the curb is being cast monolithically with the slab, I'd be tempted to nail a beveled wood strip onto the inside form and another on the outside that extends the way down at the CJ locations. It's probably overkill but since you asked. Take a look at my Guide to Floor Slabs in the link below for some additional thoughts

 

[Kaizen]

Are you sure they are not doing the curb later? I have the same set up and they did the one foot knee wall a few days later.
If they do it all at the same time they will have several pieces of rebar that should hold it under tension more then the floor.
So even if it cracks it won't seperate due the rebar. I was able to make 6 sections on my 30x36 using a diamond blade in a circular saw as i did not want a big gap.

 

[carcruse]

Got a punch list back from the city for my BP Mostly just updates to the plans to have call outs on material and specs for electrical.
Looks like I’ll be losing 6” of height . They measure height from grade or the street curb or the crown in the street. Not from the finished floor. So ill only have 11’6”

Thinking about headroom
Not the end of the world, I’ll have to duck down a little when I have my suburban on the lift i guess. Dam government overreach!!

That does not sound right. What city are you in? Can you post the actual ordinance that says that.
Typical ordinances state something like: building grade to be 18" above curb or centerline of road ( if no curb) and that you measure from building grade to median point of roof to determine height.

 

[no704]

In Tempe Az. Architect also thought it was median height also. But it is max hight 15’. Also thought it was from finished floor but it is from curb height, road crown, or natural grade.

 

[Codyboy]

That does not sound right. What city are you in? Can you post the actual ordinance that says that.
Typical ordinances state something like: building grade to be 18" above curb or centerline of road ( if no curb) and that you measure from building grade to median point of roof to determine height.

Is there a glitch in the matrix?

 

[rancherbill]

Cutting control joints is so 20th Century.

When they did my garage they used a plastic T-Bar and put it into the concrete. Did there basic power troweling etc and then pulled out the T-bar for the final finish troweling. Yes it fills in and gets smoothed out. The joint is invisible when they are finished. Then they hit it with a good professional sealer and they were done.

I had none of the expected shrinkage cracks. Months later, I noticed cracks that were less than a millimeter in a couple of areas. Because there is no joint it doesn't fill up with dirt.

I couldn't find the plastic T-bar on a search, but here's an aluminum one. The plastic ones come in a box of ?20? and they just tossed them when they were done.

 

[carcruse]

Is there a glitch in the matrix?

Must be, don't know how my reply and the quote ended up in this thread.

 

[PopcornSutton]

Cutting control joints is so 20th Century.

When they did my garage they used a plastic T-Bar and put it into the concrete. Did there basic power troweling etc and then pulled out the T-bar for the final finish troweling. Yes it fills in and gets smoothed out. The joint is invisible when they are finished. Then they hit it with a good professional sealer and they were done.

I had none of the expected shrinkage cracks. Months later, I noticed cracks that were less than a millimeter in a couple of areas. Because there is no joint it doesn't fill up with dirt.

I couldn't find the plastic T-bar on a search, but here's an aluminum one. The plastic ones come in a box of ?20? and they just tossed them when they were done.

They are very hard to put in straight while the pour is ongoing. Much easier to cut joints in after it's all down. IMHO.