Brief background: I pulled And re- installed oak (2.25X0.75) on 2nd floor.
It was inproperly fastened.

Based on your responses, I pulled the hardwood floor on the second floor (popping & crackling). It's very labor intensive, btw. I don't recommend it.
I let the hardwood sit for 1 week.
Now, I've installed about 50 square feet in one room. I used 15# felt paper, and I adhered to the proper fastening schedule. Evey 8-10 inches, and 2-3 inches from each end. The result: There is still some crackling and popping sounds. Not on every step, but perhaps one popping sound every three steps.

I did the same thing on the first floor, and there is no crackling and poppign sounds on the first floor. The only differences are:
1. I added insulation in between the first and second floor (R30, which is about 8.5" thick) I think there is still about an inch or two between the top of the insulation and the plywood.
2. The initial wood re-installation on the second floor was made with very low temperatures 40-50's in winter ( no heat)
. But I started the present installation this past Saturday, with a temperature of about 67 degrees. And its been warm the past couple of weeks or so.

Also, the floors are not perfectly level, but they are about the same as the first floor, and the first floor is not crackling or popping.

I did notice a few rare and random popping sounds on the first floor (over a 700 square feet area) and these sounds went away with time.
Could the same apply to the second floor ? If so, how long should I wait to see if the popping /crackling sounds go away ?

Could the cold temperature have damaged the hardwood ?

I'm hesitant to continue, if the popping/crackling sounds don't go away.

Any advice is greatly appreciated !

Thanks,


___________

This is a toughy to answer without on site inspection to determine the cause of the noises.
If I read you correctly, this is a floor that was installed, removed, and re-installed. Were you careful to not damage the bottom section of the groove? This is one possible origin of the noise you are hearing, but there could be many others.

Don't know but the wood could have some sloppy milling. My fastening schedule is 6" apart and about 2" from the ends and I prefer staples. Are there any HVAC lines installed in the first floor ceiling?

There are no hvac lines under floor. I has a baseboard heating.

The fastening schedule is the same that I used on first floor, and the first is fine.
Actually its really about every 8". I used 2" cleats.

Regarding checking the bottom of the groove, it's possible. I did pay close
Attention to the tongue to make sure it wasn't cracked or broken.

I think what I may try is installing 20-30 sq feet in another room, and thoroughky
Check every strip of wood for any imperfections.

Does the above make sense ?

Also the fact that the wood was installed during winter time without heat-- could this
Have damaged the wood ?

Thanks for your replies!

Dare I ask, do the cleats blow through the subfloor??
Is the subfloor plywood, or oriented strand board, or particle board?

There is a 3/4" plywood underneath. I cannot check underneath the hardwood floor since its on the second floor. But
what I can say, is that when I pulled the hardwood, the wood was tight against the plywood. And I had also used 2" cleats.

Then I would be questioning the plywood underneath, perhaps replace or add another layer if possible. Thats all I can think of besides what Jerry said, poor milling.

I would go out rent a pneumatic stapler.

Bingo was his name-o

This is a recently bought house. It had the wood installed on both floors. The wood
Could have amaximum age of 42 years old. But it was in great condition.
It was never re-finished after installation and had carpet on top.
.
Since both floors squeaked a lot, I decided to pull the wood and screw in the plywood..
I pulled the second floor first and re-installed it (with inproper fastening)
There was no heat on second floor and he temperature was cold about 40 degrees.
The floor cracked and popped a lot specially after sanding with a vibrating sander.
After consulting with this board, I pulled the wood again.

Then after about 1 week(temp in high 60's) I began to re-install about 50 sq ft, and I noticed the
Popping and crackling sounds again.

Could the wood have been damaged when it was installed at very
low temperatures and kept at low temperatures for most of winter?

If the wood can recover from the low temperature, then how long
Should I wait for the wood to recover before installation ?

Thanks for your thoughts and heIp

I Think you may have a sub-floor problem caused by pulling up the wood floor.

With that much nailing and re-nailing into the tongues of the flooring, how much integrity could they have? I would bet that a majority of the boards tongues are cracked and/or broken. That alone will cause major noise of the kind you are describing.

Is this popping and cracking noise happening with foot traffic and every step, or is it happening as it just sits there, like your laying in bed at night and you hear "pop, crack" as you try to go to sleep??

There are a number of causes that make a hardwood floor crack and pop. Based on the info a read we need to stop and regroup and start off on the right foot.
Temp. is very important, levelness off subsrate, moisture off subfloor to wood flooring. are you laying a underlayment ?

The tongue and grooves are the most important thing at this point. If the integrity of them are gone the floor is not worthy of installing.