Is it normal to have lots of hair line cracks on my 1 month poured foundation?

Question

My house is in the process of being built (frame up, plumbing). Well the concrete slab (foundation) was poured aprox. a month ago and I was looking around and found that there are lots of hair line cracks in one of the rooms and our patio. I asked the builder and he said don't worry all houses to that due to the heat. Its hard to believe him cause hes been straight up caught in lies and he says "don't worry" all the time. I have found no web site to help me and I can't keep paying for experts to keep coming out. I need help. Is this normal? I was thinking of staining that room but it would look ugly with all those hairline cracks so I can't see how thats normal, and a brand new patio with hairlines everywhere again doesn't seem normal to me.. AGGGAAHHHH..

Answer 1

Foundation? You mean a poured wall or you on a floating slab.

Pour wall; hair line cracks are shrinkage cracks. The wall was pour from the corners of the house with very wet crete. Should have been pour straight from the truck (no water added after it arrived) and vibrated down. Most contractors add the water to make the pour go faster.($) When the water evaporates you get the cracks.

Floating slab; Alot of cracks (looks like a busted windshield or a puzzle put together) alot of cement in the crete (easy to finish $) These really show up when it drys fast. Fine cracks that dont go one side to the other. Shrinkage again poured to wet/dryed to fast. Should have been kept wet so it would dry slower (damp burlap or misted with a hose) The slower the dry time the harder the crete.($)  

I pour slabs for garages and tell the people to keep it damp for a week. After the finish is done you can just mist it by the next day place a lawn sprinkler or burlap on it just keep it wet. Most of them dont have control joints (cut or vinyl) in them like WOODTICK talks about. The ones that do because they were told to put them in by someone else. The others dont have any cracks. Even going thru WI winters.

Answer 2

I have never seen that happen unless the person did not tool the concrete at all.  The best way to find out is to make sure that when the inspector comes out you are there.  Then you can take him aside and ask.  hopefully this lying contractor is licensed insured and bonded so in the event he botches your house you will be covered.  also you may want to try to go to a concrete place and just ask "my concrete floor has lots of hairline cracks and is not very old should i replace it?".  If you get tons of yes answers then you can go to him and say this is wrong, bob, Joe, Steve, frank, and sally all told me it was.  I hope this helps

Answer 3

All concrete cracks.  This is due to expansion and contraction.  Contractors install control joints to limit the cracking to a predetermined location.  This can be done in several ways.

On a sidewalk or driveway, you will see grooves that are created by tools.  On an interior slab, they either cut slots into the pour or use plastic zip strip to create the control joint.  Hope this helps.