You probably need to provide more information such as:
Is it an unstarted project (new log building) or is it an old log house that you've taken down or is there an old one already on site? In other words, where are you in the process? A follow-up question to that is what kind of foundation is it?
If you're casting a foundation, it's just a matter of laying down heating coils. If it's a crawl space, I've heard different things about underfloor heating, which I don't have an answer for...
You can easily make sliding strips/battens/tracks/washers yourself. Since many before you have wondered, I'll quickly explain.
If you have newly constructed with logs and the timber is relatively fresh, the house will settle approximately 2% due to pressure, but primarily due to shrinkage as the last moisture exits. This could be up to 10 cm in a house that is 5 meters high, but this is on the entire house height!
So, you measure the height from the sill (important) not the floor, up to the wall plate. You might get 3 meters, let's say, so that section will settle 6 cm (This is for new log building). So you measure from the intended top of the inner floor to the ceiling panel and deduct 6 cm from that...
Now you can use a router or a chainsaw to cut grooves in the stud. At the bottom, nothing is needed; you just screw straight through there, but you cut 2 grooves on the upper half of the stud at 6 cm (to be safe). Then a washer and a lag screw through that! Done!
Keep in mind that the weight on these studs comes from above, so there aren't really any forces trying to pull the studs away from the wall, hence not many screws are needed. If you are doing a bathroom and installing drywall and tiles, I would be more careful, but using the same principle, though in the rest of the house, more is not needed.