Technical guide
Flooring and underfloor heating
Which floors work over underfloor heating, why 27°C is the limit, how thermal resistance changes running costs, and the commissioning sequence that stops floors failing.
The rules that actually matter
Underfloor heating is now normal in new builds, extensions and renovations, and it changes the flooring decision more than any other single factor. Three rules cover most of it.
27°C is the ceiling
Measured at the floor surface or the adhesive line, not on the thermostat.
Thin and bonded beats thick and floating
The less material between the heat and the room, the better the floor performs.
Ramp up and down slowly
Most underfloor heating failures are commissioning failures, not product failures.
What works over underfloor heating
| Floor type | Over UFH | Notes |
|---|---|---|
| Glue-down LVT | Yes, the best option | Thin, fully bonded, no air gap, no insulating layer |
| Click SPC | Yes | Works well, but the attached underlay insulates |
| Solid wood | No | It will shrink, gap and cup. Do not specify it |
Check the individual product page. Underfloor heating suitability is listed on ours, and there are ranges with tighter conditions than the general rule.
Water-based or electric? Do not assume both are covered. Some LVT ranges are warranted for water-based systems only, and electric mat systems can produce sharper local temperature peaks. This is worth confirming on the specific product before you order, particularly for electric systems under a bonded floor.
Why glue-down conducts better
Heat has to get through the floor to reach the room. Every layer between the pipe and your feet is resistance.
Glue-down LVT is 2mm to 2.5mm of vinyl bonded directly to the screed. There is no air gap and no foam. Its thermal resistance is close to nothing. The heat goes where it is meant to go.
Click SPC is a 4mm to 6.5mm rigid board with a foam or cork underlay bonded to the back. That underlay is doing the opposite of what your heating wants. The floor still works, it just responds more slowly and costs slightly more to run.
For comparison, Elements Inspirations LVT publishes 0.039 m²K/W. Anything under roughly 0.15 m²K/W is generally considered fine for underfloor heating, and every LVT option is comfortably inside that. The differences here are about responsiveness and running cost, not about whether the system works.
The 27°C limit, and what it means
27°C is a maximum surface temperature, not a target. It is the point above which vinyl, adhesive and timber start to be pushed beyond what they are designed for. Two things follow from it.
Not a high-output heat source
Capped at 27°C, a UFH floor delivers a limited number of watts per square metre. In a poorly insulated room or a big glazed space, it may not be enough on its own, and that is a heating design question rather than a flooring one. Ask the heating designer whether the calculated output assumed a floor covering, and what resistance they allowed for.
Local hot spots break the rule
Pipes or mats running close under a thin screed, a rug covering an active zone, or a heating mat under a fitted unit can all push a small area well above the room average. Fixed furniture and rugs should not sit over active heated zones.
The commissioning sequence
This is where most problems come from. The sequence is not optional and it is not quick.
Before fitting
- Commission the system fully and run it through a complete heating cycle, including on a new screed. This is what dries the slab out.
- Bring it back down and turn it off, or down to 12°C to 15°C at the subfloor, 48 hours before fitting.
- Only now test the subfloor moisture. Testing a cold, never-heated screed tells you nothing about what happens once it warms up. Below 75% RH.
- Acclimatise the flooring in the room.
During fitting
- Room at 18°C to 24°C, floor at 15°C or above for the adhesive.
- Use a high-temperature adhesive. UZIN KE 49 HT is rated for warm water underfloor heating.
After fitting
- Leave the heating off for at least 24 hours, and let the adhesive cure. Full strength takes about three days.
- Bring the temperature back up in 3°C to 5°C steps per day until it reaches normal operating temperature, capped at 27°C.
Rushing the final step is the classic mistake. A floor that gets taken from cold to full output overnight is being asked to do all its expansion at once, while the adhesive is still curing.
Adhesive is not optional detail
On a bonded floor over underfloor heating, the adhesive is under permanent thermal cycling for the life of the floor. Every day it warms and cools, and every day the tile tries to move against it.
A standard dispersion adhesive softens as it warms and loses shear strength exactly when it needs it. A high-temperature adhesive does not. This is the single most common cause of failed floors in heated rooms, and it is entirely avoidable.
Why the right adhesive mattersSeasonal behaviour, and what is normal
Normal
A wood floor that is very slightly tighter in summer and shows hairline gaps in a dry, heated winter. Keep room humidity between 35% and 65% and this stays invisible.
Not normal
Joints opening progressively over months, tiles creeping out of line, edges lifting, cupping across boards, or a hollow sound developing. Those are installation or specification problems, and they need looking at rather than living with.
Underfloor heating combined with very dry winter air is hard on timber. If the house runs dry, a humidifier does more for a wood floor than anything else you can buy.
Rugs, furniture and zones
- Rugs trap heat. A thick rug over an active zone raises the temperature underneath it, sometimes past the limit. Use thin rugs, or turn that zone down.
- Fixed furniture should not sit over an active zone for the same reason.
- Zone the heating to match the room use rather than heating under kitchen units and wardrobes. Better for the floor and cheaper to run.
What to buy
| The situation | Choose |
|---|---|
| Underfloor heating as the primary heat source | Glue-down LVT, high-temperature adhesive |
| UFH as comfort heating in a bathroom | Glue-down LVT or click SPC |
| UFH plus DIY installation | Click SPC |
| UFH in a conservatory or garden room | Glue-down LVT, high-temperature adhesive |
| Retrofit UFH over an existing floor | Talk to us and the heating supplier before ordering |
Common questions
Can I put LVT over underfloor heating?
Yes. It is one of the best floorcoverings for it, provided the surface temperature stays at or below 27°C and it is fitted with a high-temperature adhesive.
Does click SPC work over underfloor heating?
Yes. The attached underlay makes it slower to respond and slightly more expensive to run, but it works.
Can I put solid wood over underfloor heating?
No. Choose an approved LVT or SPC floor instead.
Do I need special underlay?
No. Our click SPC has underlay already attached, and glue-down uses none. Do not add a separate underlay under click SPC over UFH; it adds resistance exactly where you do not want it.
How long before I can turn the heating on after fitting?
At least 24 hours, then increase gradually in 3°C to 5°C steps per day.
Will underfloor heating make my floor fade?
No, heat does not fade a floor. Direct sunlight does, which is a separate issue and one worth managing with blinds or UV film.
My floor feels cold even with the heating on.
Check the surface temperature at the floor rather than the room thermostat, and check what the heating design allowed for the floor covering. A floating floor with attached underlay will always respond more slowly than a bonded one.
Shop glue-down LVT or click SPC, and email us with the heating details if you want it checked before you order.