Concrete slab

[Monkey Radio]

So I am getting ready to pour the slab. To all my research I will be using a vapor barrier. The thing is that both the concrete contractor and the builder does not want to use one. He says the it will induce spider cracking on the top layer. And now they want me to sign a waver. I will doing my saw cuts in the green zone of the cure time.

Trying to find a soft cut saw is kinda tough. I have fond one 25 miles away for 65 a day + the blade at 108.00. Ouch. Or Home Depot has a hand held skill saw with a hose attachment with a diamond blade. For I sure that it is way less than 100 bucks. I am kinda leaning towards the Home Depot saw.

What do you think?

 

[uncletater]

Does your concrete contractor not have a soft cut saw?

 

[TRC51]

My contractor didn't even bat an eyelash when I asked him to put a barrier down... and he is probably one of the biggest concrete guys in the area. 2 years later and mine still looks good.... and it's poured flat.

 

[KULIWOBBY]

The reason why some guys in my area don't want to use it is because it takes longer to finish and dry. It is your floor and if you want it done tell them, do not let them not do something as simple as that because they just don't want to.

 

[willymakeit]

The vapor barrier is the only way to go. Place the aggreate then the barrier, then concrete, this keeps subsurface moisture away from your slab later. Moisture has to go somewhere and the barrier helps control it.
Watch when the concrete is being placed and dont let them punch holes in it to remove bleed water. Tape any joints with the approved tape , not duct tape.
Seems like a lot but it is worth it to avoid any issues.
If you want to know more look at some of the ACI specs.

 

[brownbagg]

as a concrete inspector, the reason contractors dont like vapor barrier because the can pour wet and the extra moisture will go out the bottom, the problem is you want concrete to set up as a unit, b the bottom being a dryer moisture than the top it will cure faster and it will crack like crazy. Building codes require vapor barrier. The other problem is without a vapor barrier, ground moisture will wick into the slabs, forever, so any type of floor covering will be impossible in controlled climate area, the slab will alway be wet

 

[csp]

the problem is you want concrete to set up as a unit, b the bottom being a dryer moisture than the top it will cure faster and it will crack like crazy.

The bottom being a drier moisture? You lost me there. Are you saying the bottom will crack or the top? With or without the vapor barrier.

Sorry, but that statement isn't very clear.

 

[rasit]

I would tell them to shove the waiver and would seriously think about getting someone else. If you sign the waiver and do the saw cuts yourself you are giving them a complete release to do the shittiest job, and not have to answer to it.

 

[Kevin54]

I would tell them to shove the waiver and would seriously think about getting someone else. If you sign the waiver and do the saw cuts yourself you are giving them a complete release to do the shittiest job, and not have to answer to it.

Totally agree with this. Also, if the concrete guys can't cut it for you, then I'd say they're not much of a concrete outfit. I have never heard where the homeowner would have to rent a concrete saw after a pour.

It sounds to me like you need to find someone else to do the 'crete work, and do it to your specs.

 

[ConCretin]

I'm with Rasit with regard to your contractor. The waiver is bush league.

The primary effect of a vapor barrier on the finishing process is increased bleed water. Mix water isn't absorbed into the sub grade so more of it is likely to rise to the surface. This shouldn't present a problem to a competent finisher.

Under normal circumstances, a vapor barrier doesn't cause spider cracking.

Spider cracking typically occurs with high slumps in hot and/or windy conditions when the surface sets up quicker than the concrete below. Finishers think the concrete is ready and proceed with finishing before the concrete can support their weight.

With regard to the saw. An early entry i.e. 'soft cut' spins into the slab and has a plate that places pressure on the surface to prevent raveling. This allows you to start cutting much earlier than you can with a normal saw.

 

[Monkey Radio]

Thank for every ones replies. Me and the contractors will be talking tomorrow.

 

[dcs Inc]

Mid range and high range water reducers. The only way to go with a vapor barrier. Tell these bozos to get lost if they don't know how to pour concrete correctly. The more moisture added to concrete (slump ratio) the greater loss of compressive strength and more shrinkage.