Radiant Floor Heating

Installing tubing in a slab or thin slab for radiant floor heating offers many great benefits. Two of the main features people love about radiant heat are the comfort of warm floors and the efficiency associated with this method of heating.

If you're planning a radiant floor heating system, either for a new construction project or for a retrofit - we do recommend enlisting the help of a competent radiant design specialist. Some things to keep in mind regardless as you prepare for a radiant slab:

• Do any excavation, filling necessary or required by local building codes

• Verify that all under slab plumbing and/or electrical services are in place

• Finish grading by leveling and tamping the fill - rake off any loose rocks or debris - the final grade should be level and allow for the thickness of both the slab and any under slab insulation

• Use 6-mill plastic sheeting for your vapor barrier - this prevents moisture from migrating upward and prevents adverse effects on floor coverings and/or adhesives

• Place your under slab and/or edge insulation

• Install welded-wire reinforcing. I normally recommend 6 by 6 wire re-mesh, because it is perfect for tubing spacing

• In many cases, if you have foam insulation down already, you can use foam staples to install your tubing and forego the wire re-mesh.

The pictures below show a vapor barrier with perimeter insulation and wire re-mesh...

It's time to lay out your tubing - this is where an accurate tubing layout will save you lots of time while giving you peace of mind knowing that a professional went over your project details and came back with their best recommendation based on years of experience.

• Locate your manifold/mechanical location - Before installing any tubing - it may help to use spray paint to mark portions of your layout - taking your cues from your printed layout.

• Begin with a coil of tubing at your manifold location (allow yourself 8 to 12 feet of extra tubing) - unroll it, don't pull it from the side of the roll (it'll kink if you do).

• Zip tie or use foam staples every two to three feet, closed if necessary at the corners and bends.

• Avoid kinking and crossing one tube over another

• Use protective elbows or bend supports where the tubing will exit the slab

• Pressure test your loops, either individually or all at once - the recommendation is 1.5 times the anticipated operating pressure or 100 psi (whichever is greater) for 30 minutes - verify that there are no leaks. You local codes may have a different requirement, so check with inspector

• Any tubing passing through/under a control joint should be sleeved

• There are several opinions on lifting tubing up into the slab - it can be done, but not in the vicinity of control joints. I recommend leaving the tubing in the bottom inch of your slab.

Below, you'll find pictures of a radiant floor heating tubing layout and an actual radiant system installation.

After all that prep work, it was time to bring in the concrete contractors and let them do the work for a change...