what to use on floor boards before laying laminate

[fredyflame]

I have a 1936 house floor boards are showing ridges through the underlay and carpet in places so they must be warped slightly
Cant really find a definitive answer to what to place under the laminate I have bought
Do I put hardboard / thin sheet plywood or mdf or those green fibreboard squares, or just thin insulation
Anybody give me some good advice as my wife is waiting for the answer as its the only excuse I have left for not actually starting the job!!
Cheers

 

[crazydaze]

It depends how bad the floor is, but it is likely that 4mm Hardboard, 4mm Fibreboard underlay and then lay the floor will do to get a good result .