Concrete slab with vapor barrier question

[arctictq]

So the concrete contractor I had do my 30'x44' slab, cut about 4 slits in the vapor barrier. Looked to me like he pounded stakes in the middle to get a depth, when pouring the floor. I questioned him about the cuts and he said when they pound the stakes down, that the cement will close the slits he made, back up.
Is this a common practice or is that kinda defeating the purpose of the vapor barrier?
Is it likely to get vapor up from them areas?

 

[Firebrick43]

Are we talking about a 2" slit or a 2' slit?

 

[RivennHewn]

BS.

Probably not a huge problem, but he’s blowing it up ur ****.

 

[arctictq]

Are we talking about a 2" slit or a 2' slit?

Yeah its about a 1 1/2" - 2" criss crossed cut. for about 4 small 1x2 stakes.
guess I just noticed there a special section for floors, sorry I'm a newb. lol

 

[ConCretin]

The cuts will negate the value of the vapor barrier in the affected areas. Incompetence aside this may or may not be a problem. Limiting moisture intrusion into finished spaces is always desirable but it's really only an issue in moist soil conditions when an adhered floor system is installed. Water vapor can ruin the bond and cause the floor covering to fail.

 

[arctictq]

The cuts will negate the value of the vapor barrier in the affected areas. Incompetence aside this may or may not be a problem. Limiting moisture intrusion into finished spaces is always desirable but it's really only an issue in moist soil conditions when an adhered floor system is installed. Water vapor can ruin the bond and cause the floor covering to fail.

Yeah I kinda thought that wasn't a good idea, I can't figure out why someone would do that. Is he honestly thinking the cement will seal the cut up? Seems pretty unlikely to me. And don't they have other ways to get the level of the floor right?
It should be pretty dry where its at, but I was just going the extra mile, thinking if I ever do decide to do an epoxy floor, that I would be covered.

 

[ConCretin]

Yeah I kinda thought that wasn't a good idea, I can't figure out why someone would do that. Is he honestly thinking the cement will seal the cut up? Seems pretty unlikely to me. And don't they have other ways to get the level of the floor right?
It should be pretty dry where its at, but I was just going the extra mile, thinking if I ever do decide to do an epoxy floor, that I would be covered.

There are other methods for establishing grade without poking holes in your vapor barrier - a basic laser level for one. It's a hack move but there are a lot of floor guys who don't understand the basics and do whatever is convenient at the time.

If you decide to do an epoxy floor at some point, you can test the floor for moisture and if it's a problem, there are products you can apply to minimize potential problems. Otherwise you'll probably never have an issue from a few cuts in the VB.

 

[arctictq]

There are other methods for establishing grade without poking holes in your vapor barrier - a basic laser level for one. It's a hack move but there are a lot of floor guys who don't understand the basics and do whatever is convenient at the time.

If you decide to do an epoxy floor at some point, you can test the floor for moisture and if it's a problem, there are products you can apply to minimize potential problems. Otherwise you'll probably never have an issue from a few cuts in the VB.

Funny the 1st Guy I had out for an estimate, said I didn't need a vapor barrier. I thought, well why not do it at this point.
He also did epoxy flooring and said he used some kind a sealer on top of the cement, to seal out the moisture. He also said his process was guaranteed for like 20 yrs or something like that. I don't know, maybe I didn't need it?

 

[Rusted Nut]

Although common practice, concrete will not seal anything. Contractor should have used a baseplate to support grade stakes. Probably not a big deal, unless you're in a moist area.

 

[ConCretin]

Funny the 1st Guy I had out for an estimate, said I didn't need a vapor barrier. I thought, well why not do it at this point.
He also did epoxy flooring and said he used some kind a sealer on top of the cement, to seal out the moisture. He also said his process was guaranteed for like 20 yrs or something like that. I don't know, maybe I didn't need it?

In addition to cost there is one potential downside from installing a vapor barrier and that is increased bleed water, which can lead to surface defects if not handled properly. For a pro this isn't a big deal but for a hack that likes to place wet concrete, it can bite you.

With that said, I always install a vapor barrier,. The benefits of your vapor barrier aren't completely nullified by a few small cuts so it wasn't a complete waste. I'm not very knowledgable regarding the surface applied vapor barriers but if the installer will offer a warranty, that counts for something.

 

[bb29510]

one of the big advantage of having vapor barrier is so the concrete doesnt dry out too quickly and start cracking, the water in the bottom layer doesnt bleed into the subsoil creating a different pressure ( not correct word but close) from the top surface and cracking starts

 

[housewolf]

Same but different, and I have no answer…

I’ve wondered the same thing when I see them driving stakes to support floats for depressed areas. “They” do it all the time, but let the ******* plumber cut a hole in the plastic and they’re shoving a roll of tape up your ***.

 

[RivennHewn]

EZ screed jacks are the best thing I’ve seen to keep from poking holes, and setting screed elevations.

Tape (from the VB manufacturer) is the correct way to seal seems and install penetration boots(kinda like the ones that go on your roof)

Duct tape and visqueen just don’t cut it anymore.

 

[juddspaintballs]

I have a question somewhat related...

I have a foundation (for a house) that I'm pouring a slab in. I put down the vapor barrier and I put down 2" foam and put PEX loops on it for heating. It rained since then and there's some water sitting on the vapor barrier under the foam that wouldn't be easy to remove by any means. Would it be worth poking a small hole in the vapor barrier to bleed that water out or let it sit on the vapor barrier for the concrete pour this week? I may be able to slap a piece of tape over a poked hole, but that isn't guaranteed.