10 Dos and Don’ts for Electrical In-Flooring Warmth


Synopsis: As vice chairman of practices for BOWA in McLean, Va., Doug Horgan has seen his justifiable share of errors in relation to electrical in-floor heating in loos and he’s seen additional errors happen when any person is available in to try to repair the issue. Horgan walks by way of set up points his crew has stumbled upon, how you can keep away from them, and what it is best to know when tackling in-floor heating initiatives.

The design-build agency I work for does renovation work in Washington, D.C., and among the surrounding suburbs. As vice chairman of finest practices, it’s a part of my job to research when issues go improper on our initiatives and to stop those self same issues from
taking place once more. Electrical in-floor warmth is specified for lots of our initiatives’ loos; sadly, I’ve seen a lot of failures, each on our personal jobs and on others the place we’ve been referred to as in to repair present issues. Purchasers are very ­sad when the expen­sive ground they had been anticipating to be toasty heat isn’t. What’s worse is that the repair is mostly troublesome and costly. I hope that by sharing what we’ve discovered over time, you possibly can keep away from the identical complications.

For starters—and this may occasionally sound apparent—it’s a must to learn the set up guide for the particular heating product you’re utilizing. We’ve had events when electricians and tilesetters put in issues incorrectly. The gen­eral contractor or undertaking supervisor ought to verify in with subcontractors throughout their components of the job to verify the work is being finished in line with the producer’s directions. What follows are some issues your lead can do to enhance your likelihood of success with in-floor electrical warmth. 

Get the wiring proper


We’ve put in wires improper and forgotten temperature sensors; we’ve put the sensors within the improper locations and underneath probably spots for rugs and bathtub mats. We’ve additionally failed to put in a contactor—an electrical change wanted for bigger flooring.


Our undertaking managers now be certain our electricians and tile installers are acquainted with all of the set up necessities, they usually make common checks to make sure the work is executed to plan. We additionally verify with the tile and electrical contractors to make sure we’ve ordered every little thing for a profitable set up.

Warmth the place there are ft

We now mark the exact fixture and cabinet layout to determine where people may be sitting or standing on the 3D mat that holds the heating wire.


We’ve missed components of the strolling floor—akin to toekicks—subsequent to bathtubs, at make-up stations, and at different areas the place ft are underneath cupboards. When individuals pay for heated flooring, they actually don’t like chilly areas the place they stand or relaxation their ft.


We now mark the precise fixture and cupboard structure to
decide the place individuals could also be sitting or standing on the 3D mat that holds the heating wire. We do that earlier than the heating wire is put in after which run it as near the traces as attainable, following the producer’s minimal clearance.


Watch moist areas

Wet areas have additional requirements to protect bathers.


Moist areas have extra necessities to guard bathers. You may’t guess at vital set up particulars like whether or not the heating wire goes on high or underneath the waterproofing or whether or not you run the wire over or by way of the curb.


Don’t guess. Verify directions for the wire package you’re utilizing, and name, textual content, or e mail tech help in case you have questions on something that varies from the positioning situations described within the primary directions.  

Thoughts the gaps

We have used presized heating mats (instead of loose wire) and have not placed them close enough together, resulting in sections of cold floor between them. We now draw out the full-scale layout on the floor and only use heating wire that we route ourselves around the bath.

We’ve got used presized heating mats (as an alternative of unfastened wire) and haven’t positioned them shut sufficient collectively, leading to sections of chilly ground between them. We’ve additionally needed to repair a ground with scorching spots the place somebody put mats too shut collectively.


We now draw out the full-scale structure on the ground and solely use heating wire that we route ourselves across the bathtub. We save the structure drawings and take footage of the set up when the wiring is completed.

Keep away from swapping tile

Avoid swapping tile


The shoppers objected to the colour of two limestone tiles on this ground, and we reduce them out to switch them and broken two adjoining tiles when making the swap. We additionally reduce the heating wire in 11 locations, voiding the guarantee. The ground failed a yr after being repaired.


Keep away from altering tiles if in any respect attainable. It nearly all the time damages the wires. Restore kits can be found, however they void the guarantee, and we’ve had additional failures even with cautious repairs.

Find wires earlier than drilling

We’ve damaged the heating wire with fasteners for shower glass. If holes are needed in a heated floor, we use our infrared camera to mark the exact location of the heating wires on blue tape to avoid them.

We’ve broken the heating wire with fasteners for bathe glass. On this case, the specialist within the picture charged us $700 to make use of a high-voltage generator to make arcing that was simpler to see together with his infrared digital camera.


If holes are wanted in a heated ground, we use our infrared digital camera to mark the precise location of the heating wires on blue tape to keep away from them.   

Avoid cupboards and fixtures

Steer clear of cabinets and fixtures


We haven’t had these explicit issues, however we’ve heard of contractors tucking extra wire underneath an arrogance or tub, which might trigger doubtlessly harmful overheating, or working the wire too near a closet flange and melting the wax ring.


A full-scale structure drawn on the plastic mat that holds the heating wire solves these issues. Don’t run the heating wire underneath cupboards or bathtubs, and preserve the manufacturer-required clearances to fixtures. Preserve clearances to warmth sources like ducts, radiators, and pipes.

Shield the wire throughout setting

Sometimes trowels nick the wires when the tile is being set on top of the heating system. Manufacturers of heating systems offer continuity alarms that sound when a wire is cut



Typically trowels nick the wires when the tile is being set on high of the heating system. It’s very laborious to trace down the harm as soon as the ground is completed.


Producers of heating methods provide continuity alarms that sound when a wire is reduce. We’ve got our tile subcontractor present and use one in every of these alarms. It’s in place by way of glass set up.

Know the resistance

Know the resistance


The heating wire has a specified resistance ranking measured in ohms that you just’ll discover on a label connected to the top. When you pull off the label it’s a lot more durable to find out what the resistance needs to be for testing.


We’ve got electricians go away the label on the wire, or no less than put it within the junction field. We are able to check that cable at any level throughout development to substantiate it’s intact. Different vital data for recollects or repairs can be on that label.

Say it loud

danger no holes in floor sign

Say it loud
Picture: Lewis Hoke, courtesy of the writer


Anybody drilling in or close to a heated tile ground can harm it; they could don’t know that the ground is heated, they usually may drill by way of a heating cable and destroy it.


One of many best methods to stop issues is to alert staff and subcontractors that there are embedded wires within the ground. Hold indicators and inform shower-glass subs, plumbers, and anybody else who could also be drilling the ground that you just’ll have to mark the wires utilizing an IR digital camera earlier than any drilling can happen. 

Doug Horgan is vice chairman of finest practices for BOWA in ­McLean, Va. Photographs by the writer. 

From Tremendous Homebuilding #308


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