First, thanks for this site. I've already picked up a lot of useful information.

So, I quick bit of info on our place. My fiancée and I just purchased a 2nd floor condo in a suburb of Chicago. The current carpet floors need to be replaced, and we would like to put in wood flooring throughout (minus the two bathrooms, kitchen, and laundry room.) It's about 1000 SF. The makeup of the building is CMU/brick with precast concrete flooring (Flexicore, Spancrete… Not sure on the mnfg.) And this is where my questions arise.

At this point, we haven't taken the carpet out, so I'm not sure if there is a subfloor or not, but I doubt there is. What would be the installation procedure with precast concrete? Would it be the same as with a concrete slab? I would assume that we wouldn't be able to nail into it (that would most likely be a question for the Home Owners Association…)

I would like to do it myself, if possible. I would rather not install a subfloor, if I don't have to. I don't want to have to recut all the jams and doors, and mess with the appliances too much, etc. As the son of a carpenter, I'm weary of the glue down method, even if it's installed by a professional. Although these two options seem viable, but probably not worth the effort/cost.

The other method I see is the floating floor method. This seems like it may be the best option, but I have some questions with it as well. There are joints created by the beveled edges of the precast conc in the ceiling. I'm assuming they are in the floor as well, although they may have been filled so that you couldn't feel them through the carpeting. Can/should these be filled with a floor leveling cement? Would it also make sense to install my flooring perpendicular to this joint, to avoid stress on the tongue if it falls in line with the joint?

Finally, since I am installing new flooring in most of the residence, there would be one section from the living room, down the hallway, into one of the bedrooms that would all in one shot, about 34 ft +/-. The expansion in this run worries me. Would it be okay to install this continuously, or would it be better to install expansion joints with thresholds at the doorway to the bedroom, and the beginning of the hallway?

I'm sure I'm not the first person with these problems/questions. But I was having trouble finding any answers to them specifically on the web. I would appreciate any insight or help in the matter.

A floating installation will definitely be your least involved of the options, and will do fine in that application. As long as the expansion joints aren't spaced more than a fraction of an inch apart, you really shouldn't have to worry about them. In a floating application, the most important thing is overall flatness of the subfloor; do your due diligence in evaluating the subfloor before installation. Most manufacturer's require the floor be flat to approx 3/16" per 8-10' span.

Regarding the long run (37') of flooring, I've always been an advocate of incorporating expansion space with the use of transition strips. Some people want the floor to flow throughout, but the larger the span you're covering, the more expansion you have to account for, especially in a floating application. Using a t-mold at the doorways between rooms and the hall builds in extra expansion space and eliminates areas that could torque or bind, leading to gapping or buckling later.