Hi,
We put a small (10'x18') addition spanning the back of our brownstone. We put in a concrete floor with radiant heat. It was poured in March of 2014. Our contractor warned us we might get hairline cracks throughout the floor as it dried, but until yesterday, the only cracks were near the perimeter where the concrete had to go around some steel supports. The subcontractor did a wet machine-troweled surface, and we really love both the look and feel of it. We used a low-voc penetrating sealer and everything was great.
Then, yesterday, my husband heard a loud "pop" from the next room and we realized that the floor had cracked edge to edge right down the middle of the floor. (It was our first really cold morning in NYC - below freezing - and the radiant heat has been doing a great job.) I'm heartbroken, and concerned that more cracks are going to form. My contractor came by this morning and said, basically, "I told you so," and that I should expect more cracks. I'm just wondering, is this normal? inevitable? preventable? This crack seems a lot bigger than the "hairline" cracks he warned me about. At this point, I'd like to do anything I can to keep it from getting worse. Taking a jackhammer to my new addition is not feasible, so I'm trying to learn to see it as a beautiful imperfection. But I'd also like to know if something was done wrong here.
Thanks for any feedback/advice!