Thanks for your speedy answer as regards the vapour barrier under our crawl space. You did not , however, tell us if 1/4" MDF board was suitable to use to bring the floor level even with the existing subfloor, before applying the oak strips.
Answer:
Sorry. I do not believe it is recommended for that purpose in tht it might delaminate with time and then you could be into replacing the whole floor again. You may have to go with sheet underlay such as poplar or mahogany.
