Patching hole in concrete slab

[semto]

Hi,
I am getting ready to patch a hole that I made in the concrete slab to add a shower to a basement bathroom.

I have refilled the hole about 6 inches (with the same dirt that I got out) and compacted with a garden tamper. Is that sufficient compaction before I add another layer? Is there any way of 'measuring' the compaction? When do I know that I can add another layer? Or does it not matter too much? I am building a shower over the slab so it would be really bad if it were to crack...

I am thinking of using rebar for the concrete. Any suggestions as to how I would lay that out?

Thanks in advance!

 

[Bluebinky]

You need to use a san-tee and a separate vent. It looks like the "vent" is really a drain for something else...

 

[Sponsor]

 

[Dj2]

After you properly finish and wrap your plumbing connection (is it permitted, will you have a city inspector sign it off?) find out form your building dept how to do the slab. Minimum requirements vary from region to region.

In my area, we put 2" gravel, 6 mm visqueen (or 10 mm if you can find it). You want to use rebars? 1/2" (#4) 12" apart going east-west and north-south. Concrete should be a minimum of 3-1/2" deep, and bring it up to the existing slab. Check if you need insulation.

 

[Widgit Maker]

If you have put all the soil in that you to out then you obviously have compacted it more than it was compacted before. I would fill the remainder of the hole with gravel. No compaction of gravel is necessary. I would not use re-bar for such a small hole. If it makes you feel better use a little wire in the bottom third of the concrete patch.

 

[semto]

You need to use a san-tee and a separate vent. It looks like the "vent" is really a drain for something else...

Hi,
Sorry the small picture but the vent is an actual vent. It is used as a wet vent for the shower a sink and a toilet in this bathroom.

 

[semto]

After you properly finish and wrap your plumbing connection (is it permitted, will you have a city inspector sign it off?) find out form your building dept how to do the slab. Minimum requirements vary from region to region.

In my area, we put 2" gravel, 6 mm visqueen (or 10 mm if you can find it). You want to use rebars? 1/2" (#4) 12" apart going east-west and north-south. Concrete should be a minimum of 3-1/2" deep, and bring it up to the existing slab. Check if you need insulation.

Thanks for your reply. The plumbing has been inspected and passed. He didn't do a pressure test as someone suggested on here, maybe because it is an addition to an existing bathroom? I will look into the slab requirements but I figured it would be fine if I matched the existing slab? Thanks again!

 

[semto]

If you have put all the soil in that you to out then you obviously have compacted it more than it was compacted before. I would fill the remainder of the hole with gravel. No compaction of gravel is necessary. I would not use re-bar for such a small hole. If it makes you feel better use a little wire in the bottom third of the concrete patch.

Thank you, that makes sense to try and get in as much of the soil that I took out. That answers much of my question. I agree it is a small hole but since I am building a shower over it, I want to be extra careful and do rebars even if it may be overkill. I am especially worried because one side is just the wall and nothing would be supporting the slab...

 

[hj]

If, as it appears, you connected to a line going down on an angle, the inspector must have been one of those who failed as a plumbing contractor so he because an inspector, since he did NOT recognize an "S" trap when he saw one. It should have been connected with a sanitary tee, NOT a combination Y-1/8 bend.

 

[Terry]

If, as it appears, you connected to a line going down on an angle, the inspector must have been one of those who failed as a plumbing contractor so he because an inspector, since he did NOT recognize an "S" trap when he saw one. It should have been connected with a sanitary tee, NOT a combination Y-1/8 bend.

Yes. It should have been a santee.
The lav wet vents the shower. The plumber almost had it right.

 

[Sluggo]

The last time I patched a hole like that I used a masonry bit to put several 2 inch deep holes around the perimeter. Then I took 4 inch lengths of rebar and epoxied them in to the holes. That way the patch was tied in to the rest of the slab and I didn't have to worry about any part of it dropping. Might be overkill, but I didn't worry about the tile job sitting on top of it afterwards.

 

[semto]

Yes. It should have been a santee.
The lav wet vents the shower. The plumber almost had it right.

Is this a huge issue? Would it be worth disassembling the whole thing now? I have tried it with water down the shower drain. I haven't noticed
the p-trap being siphoned out. Thanks!

 

[hj]

Unless the cut was made by a concrete saw and it was perfectly smooth and perpendicular, there is no way the concrete is going to "sink"

 

[semto]

The last time I patched a hole like that I used a masonry bit to put several 2 inch deep holes around the perimeter. Then I took 4 inch lengths of rebar and epoxied them in to the holes. That way the patch was tied in to the rest of the slab and I didn't have to worry about any part of it dropping. Might be overkill, but I didn't worry about the tile job sitting on top of it afterwards.

Thanks for your reply! I think that should work very well especially in the narrow area near the toilet drain. I am still wondering if it may be worth having rebars all the way across in the wider area. The added work does not seem to be too much.