These hangers usually can be found in several different lengths to accommodate joists which are 1-6' or 2-4' on-center. Install your hangers about 2' below the sub-floor and place them out about every 3-feet. This can give plenty to you of room to lay the tubing in position. You'll just place the tubing on the top of Joist Heating Hangers and give it time to move on the braces.. Dig up more about Printers Merge Offering Advantage Over Staples.com For Envelope, Staple And Others by browsing our unusual essay.