Referring to the downstairs, when my house was built (about 12 years ago) the builders installed 1/4" luan board as a subfloor in the kitchen and foyer to lay linoleum. The rest of the downstairs had carpet with no luan subfloor. The previous owner installed a cheap floating floor throughout the entire downstairs but didn't remove the luan and didn't install a subfloor where the carpet was.

Due to this, there are lumps in the floor where the luan ends and you can also see the planks move when you walk on the old carpet area where there is no luan. The older carpet area just has plywood squares that aren't very level.

I want to install a new, quality floating floor. Would you recomment just installing the 1/4" luan throughout the remainder of the downstairs or ripping up the luan and installing a new subfloor throughout the entire downstairs?

Thanks in advance for any help.

Luan is not a substantial material for sub flooring. But since you are floating your next floor, it isn't as critical to go over 3/4" plywood as it would be with a staple down installation.

Do you know what is underneath the luan ? I can't imagine that your home has no subfloor other than the layer of luan .There must be something between it and your floor joists .

Optimally, you should have a 3/4 plywood subfloor screwed to the floor joists and then you would want to remove the luan and then install your floating floor.

It's optional.As long as the existing luan is in sound condition you can install laminate over it.

As stated..You can install a floating floor over Luan.
That being said... From what your describing, I would probably tear out the Luan and prep the existing plywood in all the other downstairs areas. Makes no sense to me to sheet out all the areas with Luan. It's a poor quality underlayment. Besides ...you would have to prep and flatten the subfloor anyway before sheeting out over the top of it. So why not tear it out and start from scratch, right. Install over the existing subfloor.

Makes sense. Thanks for all of your advice.