Due to heavy rain last year and poor job by previous installer, moisture sipped under the hardwood floor. Floor is wrapped at 3 places with about 50-60 SQ FT . Size of the room is around 310 SQ FT. Hardwood is glued on the slab (house does not have basement).
Couple of questions.
-Can existing wood be reused except damaged one? I asked one installer and he wants to put new wood floor on entire 310 SQ FT. He told me that it is difficult to get glue removed from bottom. I am not sure he is some other motive. Personally, I do not like go things to waste when it is good condition.
-What's best option to put floor on the slab? Installer advised 2 options. 1) Engineered floor with special Plastic under it to prevent moisture at $4/SQ FT installation cost 2) Hardwood floor with sub-floor and special plastic under it at $5/SQ FT installation cost.

I will appreciate your insights as I am new in area of hardwood floor re-installation.
Thank you,

Mositure can get to a hardwood floor from the top to remember, as in high relative humidity. I'd like to know specifically why you think it is the installers fault. What do you think he did wrong? Did you have a flood, or water leak?