We just bought a 30 year old house and want to have 3/4" oak hardwoods installed in certain parts. Half the house is crawlspace and half is basement. The subfloor appears to be 1/2" CD plywood with a 5/8" particle board underlayment over it. Our installer wants the particle board removed in areas for hardwoods and not removed in new carpeting areas. The installer got a 14 and 16 reading on moisture meter in areas over crawlspace where hardwoods will go. Since we have bit of a moisture question, we're installing 2 power foundation vents in crawlspace to help that issue even though a highly reputable foundation expert said the crawlspace is dry and clean and felt there is no moisture problem.

Sorry for all the background but I thought it may be necessary. Finally my question ..... is it really necessary to remove the particle board for the oak flooring or is there another solution?? Any thoughts and/or suggestions you have would be greatly appreciated.

the particle board MUST be removed. Have you ever put a nail or screw in particle board? It basically disengrates. If you dont remove it, I doubt the installer would even do the job. I know I would walk.

If you want a 3/4" nailed down hardwood floor, the particle board should be removed. You could have a floating floor installed over that particle board. Congratulations on finding what appears to be a conscientious installer who cares how your flooring will perform. Please read:
http://www.hardwoodinstaller.com/hardwo ... .php?t=385

Thanks. I appreciate the responses.