We are having unfinished maple installed. Today the carpet was removed and we found that the floor is concrete. Contractor gave us an option to add some type of plywood or do preengineered flooring. Also since we have pre-existing unfinished wood in kitchen and bathroom, they are talking about some height difference on the floor. Not sure what I should do, the reason we went with unfinished was to match the previous wood, but now they wont even be the same height. Sounds like an eyesore and potential tripping hazard to me. At this point we are in for a stocking fee if we change our minds on the wood, but not sure whats preferrable, don't know much about engineered wood, how will this blend with the old one.

Any disavantage with using preengineered next to unfinished. Is preengineered an inferior product. I am so confused.

So Lola, how is your existing unfinished wood installed? By using the term "preengineered". Do you mean prefinished engineered or just unfinished engineered? If your contractor suggested using ply under the solid to keep the flooring the same height then you are probably stuck doing that.

And also, how come they let you buy solid if they knew you had a concrete substrate and not tell you you needed plywood to go with it? Was it a Box store?