Conservatories and garden rooms are the toughest environment in a house for a floor covering. Summer temperatures can exceed 45°C at floor level and winter nights can approach freezing, all within a glazed box that also floods the floor with UV. Extensions bring a different problem: a brand-new slab that is still full of water.
Why conservatories break floors
Thermal movement is the main issue. Every floor covering expands and contracts with temperature, and in a glazed room the daily swing is several times greater than in a normal room. Floating floors respond by pushing outwards, and if the expansion gap is inadequate they peak in the middle or buckle at the threshold.
UV is the second. Direct sunlight over years fades printed decorative layers and can yellow some vinyls. It also creates a visible line where a rug or a piece of furniture has shaded part of the floor, which does not recover.
Condensation is the third. Cold glass in winter drips onto the perimeter, so the edges of a conservatory floor see more moisture than anywhere else in the room.
What to fit
Glue-down LVT is the correct answer in most conservatories. Being fully bonded to the subfloor, it has no capacity to move independently and therefore no ability to buckle. Choose a product the manufacturer explicitly approves for conservatory use, with a UV-stable wear layer, and use a temperature-tolerant adhesive.
Porcelain tile is the other reliable option, and it is completely unaffected by UV or heat. It is cold in winter unless paired with underfloor heating, but in a conservatory used mainly in warm months that may not matter.
Avoid click flooring, laminate and engineered wood unless the manufacturer specifically warrants conservatory use — most explicitly exclude it, which means a buckled floor is not a warranty claim. Solid wood is out of the question.
- Best: glue-down LVT with UV-stable wear layer and heat-tolerant adhesive
- Also good: porcelain tile, ideally with underfloor heating
- Avoid: click LVT, laminate, engineered wood, solid wood
- Check the manufacturer warranty explicitly covers conservatories
New extensions: the screed drying problem
A new concrete or sand-cement screed contains a great deal of water, and it dries at roughly one millimetre per day for the first 50mm — so a 75mm screed can take three months or more before it is ready for an impermeable floor covering. Liquid anhydrite screeds have their own, usually faster, drying schedule.
This is the single most common cause of failure in newly extended homes. The floor goes down as soon as the builders leave, the moisture cannot escape upwards through the vinyl, and six months later the adhesive has failed or the edges are lifting.
The correct approach is a hygrometer test. Readings should be below 75% relative humidity before an impermeable floor is bonded. If the programme cannot wait, a surface damp-proof membrane — a two-part epoxy applied to the slab — suppresses the remaining moisture and allows fitting to proceed. It adds £8–£14 per square metre and it is cheap insurance.
Underfloor heating in extensions
Most new extensions in Kent are built with wet underfloor heating in the screed, which makes glue-down LVT an even better fit — it is thin, conducts heat efficiently and cannot lift.
The commissioning sequence matters enormously here. The screed must be fully cured, then the heating cycled up to maximum in stages and back down before the floor is laid, then kept low for 48 hours after fitting. Skipping this traps moisture and guarantees problems.
Keep the total tog of the floor build-up under 2.5, and specify a floor sensor so the surface never exceeds 27°C. Where an extension opens into an existing carpeted room, remember the two floors will feel very different — planning a consistent hard floor across the opening usually looks and works better.
Practical detailing
Perimeter expansion. Even a glue-down floor needs a small gap at the glazing frame, sealed with a flexible bead rather than filled rigid. In a conservatory this also handles the condensation run-off.
Threshold between the extension and the house. This is where two different slabs, often at slightly different levels and with different movement characteristics, meet. Use a proper movement joint or trim rather than running the floor rigidly across.
Blinds or solar film. Reducing direct sun does more to preserve a conservatory floor than any product specification, and it makes the room usable in July as well.
Finally, get the moisture test done before you order the flooring, not after it has been delivered. A three-week wait for a slab to dry is an inconvenience; relaying a failed floor in a finished extension is a genuinely expensive and disruptive job.
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Frequently asked questions
What flooring is best in a conservatory?
Glue-down LVT with a UV-stable wear layer and a heat-tolerant adhesive, or porcelain tile. Both cope with large temperature swings; floating floors risk buckling.
Can I lay laminate in a conservatory?
Most manufacturers exclude conservatories from their warranty because of thermal movement and UV fading. It is not recommended — glue-down LVT is the reliable alternative.
How long should a new screed dry before flooring?
Roughly one millimetre per day for the first 50mm, so a 75mm screed can need three months. A hygrometer reading below 75% relative humidity is the reliable test, or apply a surface damp-proof membrane to proceed sooner.
Does sunlight fade flooring?
Yes. Prolonged direct UV fades printed decorative layers and can leave permanent shading lines under rugs and furniture. Choose a UV-stable product and consider blinds or solar film.