installing a used wood flooring

They will squeak like crazy unless you tongue and groove them.

did you mean the subfloor to be tongue and groove?

Yeh if you butt them up against each other they will creak unless they are T&G. Did you leave a little space between them?

If the 1x4 s are not on absolutely flat concrete there will be little gaps between the 1x4 and the concrete. If you attached them to the concrete it MAY help by sucking the 1x4's down but the 1x4's may still bend a bit and make the floor squeak.

Also the actual flooring is most likely not designed for laying on floor joints (what your 1x4's basically are) but for on a continuous sub floor. All your butt joints must fall on a 1x4 or they will be unsupported and flex. If its standard random length 3/4" Bruce like flooring you going to waste a ton of wood. Also the way the tongues and grooves are cut are not designed to support a gap.

You would be better off attaching a minimum of 5/8 subfloor over your 1x4's and then laying the new floor.

thanks for your response my subfloor (the 1 x 4 ) are are on a 90 deg to the wood floor slats since the floor has to expand i left 3/8 space to the walls if were to nail the subflloor or screw it the concrete how would the floor expand without buckling

ps we used to have carpet and padding previousley so the 1 x 4 are just plain no grooves or anything

thanks again

I'm curious, why didn't you just put 3/4" pt plywood down on the felt paper, then put your wood flooring down? Unless you already have a water problem, this should be an exceptable method for a wood floor over concrete. Lou