by Neil Bauman, Ph.D.
A man explained,
I am remodeling my house and want to add one or more rooms loops. Both the floor and ceiling are being redone so I could put the loop above the drywall or below the new oak floor. Will a loop work in either of these positions, and if so which one would be better?
In your specific situation, I think either position will work as well as the other.
However, there are some situations where one is better than the other. For example, if your floor is on a concrete slab, the metal rebar or wire mesh in the concrete will negatively affect the loop signal. In that case, it might be better (and easier) to put the loop in the ceiling. Otherwise, instead of putting in a perimeter loop, you might have to use a square figure-eight configuration, or even a triple figure-eight (what we call a snowman because of the three sections just like in a snowman) and/or you might have to use a larger loop amplifier.
If your floor is not on a concrete slab then putting the loop either on or under the floor will work great. When I looped my house, since I had an unfinished basement, I stapled the loop wire to the floor joists and ran the loop leads up through a small hole in the floor to my TV. I did much the same in the crawl space under my new office. Both loops work great!
Conversely, if there is a lot of metal in your ceiling—for example, a dropped ceiling—then again, all that metal will negatively affect your loop signal. Thus, putting the loop on/under the floor would likely be better. If, as is your case, you just have the standard drywall ceiling and not much metal up there apart from the house wiring—then the ceiling location will work just fine.
Note, as with metal in a concrete floor, if you have to put a loop in a ceiling that has lots of metal in it, you may have to use the square figure-eight or snowman loop configurations and/or use a larger loop amplifier.