Measurements are taken from the center of one joist to the other not the distance between the joists.
How to install heating cables between floor joists.
Feed it into the bay between the neighboring joists through predrilled holes.
4 drill a 1 inch hole into the cross joist.
The heating cable must be gfci protected.
3 drill a 1 2 inch hole into each joist so that you can access the cavity on both sides of each joist.
Heating panels are available for joists with 12 16 and 24 inch spacing.
When you have snaked tubing from one side of the room to the other hold it in place with aluminum plates stapled to the subfloor.
Plastic like pex is not a good transfer medium says richard.
In joist foil boards.
In most cases you ll need to run a new circuit on a 15 or 20 amp breaker.
Installing hydronic heat start at a corner of the room and run tubing to the other side between the joists.
So the aluminum sucks the heat out and conducts it to the subfloor.
2 drill a 2 inch hole into the floor directly above each joist between the access panel and the wall on which the cable will terminate.
A standard installation for this system assuming the joists are deep enough would be to fix batons to the sides of the joists about 70mm from the top of the joist then a 50mm foiled faced insulation like celotex kingspan is cut and placed onto the batons the pipe work is then clipped directly into the spreader plates.
When installing the system the thin heating panels are cut to their proper length then stapled between the floor joists.
After stapling the radiant heating elements between the floor joists and making the electrical connections insulation is installed underneath the heating element.
Install the circuit then install the thermostat that turns on the heated floor.