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I want to build a dog kennel/run that is 4' x 8'. I am planning on pouring a 4" concrete slab. However, part of my design is that I would like the slab to have raised edges all the way around it (except for an opening for drainage). Should I form and pour everything all at once or do it in steps? I'm not sure of the best way to accomplish this.

Here is a cross-section of what I'm trying to accomplish with the concrete slab. enter image description here

  • I sure hope the dog is tiny, if 4x8 feet is it's "run." – Ecnerwal May 2 '17 at 14:31
  • @Ecnerwal He's a tiny guy, about 15lbs. I guess it's more of a kennel though. – Programmer May 2 '17 at 14:32
  • From the looks of your diagram your curbing is only looking to only be about four inches wide. I would encourage you to widen this to about six inches so that there is much less possibility of the curbing chipping off. – Michael Karas May 2 '17 at 14:46
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    Concrete is always better if it is poured all together as this is the best way to knit it all together so that it stays in one piece. One alternative that is often done when building something on a floating slab where curbing is desired is to just make flat slab and then establish the curbing by laying blocks along the edges. – Michael Karas May 2 '17 at 14:52
  • Before you expend the resources to build this kennel consider how you plan to use it for this 15-lb dog. Will this dog spend the day there while the family is at work or in activities that do not include the dog? Other than that will the dog be inside with the people? Or will the dog spend nearly all its time in this kennel? If the latter, the dog will be miserable being separated from the people. And a dog will not like being confined in a small enclosure with its feces and urine. – Jim Stewart May 2 '17 at 16:10
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If you don't care about leaks (or want drainage, so the dog is drier) forming the rim, pouring the rim, and then pouring the central slab is similar to whats typically done in a house basement. The joint between the rim and the slab will generally leak. If you pour a slab and then pour the raised edges on top, expect failure - if to scale, those are very thin sections of concrete and would be quite weak. You could key them with a form board into the slab face to improve the mechanical bond and thickness of the additional pour, but on this scale that's not much different from just pouring the rim first.

The usual reason for attempting to pour a structure like that all at once is to have it be waterproof - a monolithic pour will be much better at that - but's more complicated to do, as you either need to form the top of the depressed area, or (more commonly) form the rim so that the inside form is open, pour the rim (letting it ooze to the inside) and judge the slump and initial set such that you can get the top of the rim struck off without overfilling the central area, yet still be able to strike off the central area. In this case, that would seem to make things wetter for the dog, so I don't see it as an avantage.

For the easy approach, consider using 4" concrete bond blocks for the rim - no separate form to build, just lay the blocks, pour them full, and then pour the middle. Toss in couple sticks of rebar to make it robust for not much money.

  • I should have specified that I intend on having an opening so that the water can drain off the slab. – Programmer May 2 '17 at 14:51
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    Paragraph two covers the usual approach fairly well. Do note that this is advanced masonry and not for the novice. Judgement from experience regarding timing, technique and workflow is crucial. I suggest making a friend of a local mason and providing good beer. – isherwood May 2 '17 at 14:54

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