I have a two 1/2 year old one story house that makes popping noises as we walk across the floors in most areas of the house. It sounds like the floors move causing the flooring and walls to pop. We have a crawl space so I have looked under the house. The joints are 2x12, installed in hangers on one side of the house. The joists are spaced 16" on center. There are two support beam systems, giving us three areas of span, all between 13 and 16 feet.
What do I need to check to find the cause and what are possible fixes?

Probably the subfloor was not glued to the joists, and possibly the wrong nails were used. and possibly what you hear is the subfloor sliding up and down on the nails as you walk across the floor. There are a lot of "possiblies" and "probablies" because I can't see the house to evaluate the problem first hand.

If it is the subfloor moving, then the simplest cure, although it won't be fun, is to drive screws up through the joists at an angle into the subfloor, to pull the subfloor toght to the joists. Sometimes if there is carpet on the floor, they drive special screws right through the carpet to accomplish the same thing.

Best approach would be to have a good carpenter look at the house and evaluate the problem before deciding on a solution.

Thanks Richard. I have looked at the joists and subfloor and can see glue thats squeezed out from between the two, at least in the area I was looking at. How long of a screw should I use?

Maybe they applied too much glue, and it began to skin over before they could get the subfloor on it, in which case it would be there, but wouldn't be functioning everywhere. Th elength of screw depends on the angle that you use, and on the thickness of the subfloor...(making a little sketch)...OK, if you start your screw abou 1 1/2 inches down from the top of the joist, and drive it at approximately a 30 degree angle, you would use a 2 1/2 inch screw. You want it to penetrate almost all the way into the subfloor. (This assumes you have 3/4 inch subfloor and 2x joists)

Thanks again. I measured the depth of the band at the top of the joist, its 1 3/4 inches. The subfloor is 5/8 in. 2 1/2 inch screws still good?

I don't know what you mean by "band at the top of the joists"...could it be that you have composite joists and not 2x12s? The length of the screw should be chosen so that it goes ALMOST all the way through the subfloor.

Another thing occurs to me: is the problem in areas where you have wood flooring? If so, maybe you have a different problem. If that's the case, why not have a flooring contractor look at your house? Somebody should see it first-hand and give an opinion before you tackle any remedial work, because otherwise you might be wasting time and effort.

Sorry Richard, yes they are composite joists. Understand on the screw length. We'll get some experts in to hear the problem and look around. Thanks