The Pex tubing needs to run up and down each joist bay. The kit I bought had two 300 foot pieces of tubing. I snaked the tubing through the joist bay at the furthest end of the garage and started working backward.

Here is the end of the tubing...the other end is out in the back yard. It was tough keeping the tubing from getting twisted while so much of it is laying in a big pile in the back yard.

Here is a close up of the first joist bay. One of the ends goes all the way back to the basement and the other end needs to go down and back each of the joist bays. Lot of fun!

Here is the tubing going down toward the basement.

And finally. The first section of tubing is finished. Now I will move on to the next section that goes under the bathroom.