Hello: I had a pipe burst in my dining room ceiling recently that spewed water for approx. a half hour or so before I found it and shut off the water. Water penetrated the floor and surrounding walls & dropped into my unfinished basement. My dining room had blueboard with veneer plaster covering and then wallpaper. I cleaned the area in about 8-10 hours and then had a restoration co. dry the area out for approx. a week with blowers & large dehumidifiers. My concern is the blueboard behind the plaster in the bottom of the walls where the water penetrated. Should that be replaced since everything I read is that when drywall (aka blueboard) gets wet, mold can form eventually & as a result it should likely be replaced. Is that true? My contractor says since the outer plaster is hard, that the drywall behind such is likely OK, is that statement accurate or not?

Also, I presume my plywood flooring drys out OK and does not need replaced. I removed the wet carpet and padding within a few hours of the incident and dry vac'd the plywood floors. There is some back coler stains near the corners of some walls etc. My contractor says it's not mold & is normal. Is that correct or should I be concerned?

Thanks for any advice.

http://video.bobvila.com/m/21320806/applying-plaster-to-blue-board.htm