Boilers & Heating
Underfloor heating installation
TL;DR
Wet underfloor heating (UFH) fitted in a typical extension is £75–£110 per square metre supply and fit — a 25m² kitchen extension is around £2,200–£2,900. Retrofit into an existing floor is more expensive because of the low-profile overlay (£110–£150/m²). UFH is 20–30% more efficient than radiators when paired with a modern condensing boiler and 40%+ more efficient with a heat pump, because it runs at 35–45°C flow instead of 65–75°C.
Wet underfloor heating replaces radiators with a network of small-bore plastic pipe embedded in your floor. Because it heats the whole floor area evenly and runs at low temperatures, it's noticeably more comfortable, opens up wall space, and is significantly more efficient — especially with a condensing boiler or heat pump.
This page covers the three install methods, honest costs by system, and why heat-pump-ready UFH is a different spec from boiler-fed UFH.
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Three ways to fit underfloor heating
The right system depends on whether you're pouring a new floor, overlaying an existing one, or working between joists. Get this wrong and you'll either lose room height, get poor heat output, or pay to lift a finished floor twice.
- Screeded system (new build/extension) — pipe clipped into insulation, screed poured over. Highest heat output, £75–£110/m² fitted.
- Low-profile overlay (retrofit) — 15–25mm panels with pre-routed pipe channels, laid over existing floor. £110–£150/m² fitted. Only 15–25mm build-up so doors and skirtings usually don't need altering.
- Suspended timber floor (between joists) — pipe clipped to spreader plates between joists, insulated below. £85–£120/m² fitted. Best for a whole first-floor UFH retrofit.
The manifold — the brain of the system
Every UFH system has a manifold in a discrete cupboard that distributes flow to each room's loop. It has a mixing valve (blends hot flow from your boiler down to the 40°C UFH needs), a pump, isolation valves, flow meters (so we can balance each loop), and actuators on each loop controlled by that room's thermostat. Skip the flow meters and you can't balance the system — some rooms will overheat, others will never get warm.
- Blending valve — reduces boiler flow to 35–45°C for UFH
- Circulator pump — moves water through the loops
- Flow meters (one per loop) — for proper balancing
- Actuators — open/close each loop on demand
- Individual room thermostats — wired or wireless
Building Regs, Part L and heat-loss calculations
Part L 2022 requires proper design and commissioning of new heating systems. That means a room-by-room heat-loss calculation, pipe centres (spacing) matched to that loss, floor covering thermal resistance factored in (thick carpet on top of UFH kills its output), and a commissioning report at handover. Any UFH extension is also notifiable to Building Control under Part L — normally handled via a competent-person scheme.
UFH with a heat pump — it's a different spec
Heat pumps deliver 35–40°C flow, so UFH is their ideal emitter. But that means the pipe centres need to be tighter (150mm centres instead of 200mm) and every room needs enough floor area to meet its full heat loss at those low temperatures. Retrofitting UFH onto a heat pump upgrade requires a fresh heat-loss survey; the design that worked with a 60°C boiler often doesn't work at 40°C.
Typical prices
Real-world ranges from recent Northwest jobs. Your final price is confirmed in writing before any work starts.
| Item | Typical price | Notes |
|---|---|---|
| Screeded UFH (new build/extension) | 75 – 110 | Per m², typical residential |
| Low-profile overlay (retrofit) | 110 – 150 | Per m², 15–25mm build-up |
| Between-joist system (suspended timber) | 85 – 120 | Per m², first-floor retrofit |
| Manifold + pump + valves (up to 6 loops) | 650 – 950 | Included in per-m² price above |
| Additional room thermostat (wireless) | 85 – 145 | Each, installed |
| Balancing & commissioning report | 0 | Included in every install |
| Design and heat-loss calc (retrofit) | 150 – 350 | Deducted if you proceed with install |
Which brand should you fit?
We install Uponor, Nu-Heat and Wavin AHC systems as our default — all full-system manufacturers with 25-year pipe warranties and proper design support. Manifolds are typically Uponor stainless with individual flow meters. No mixed-brand components — that's how warranties get invalidated. We install and service Worcester Bosch, Vaillant, Ideal, Baxi, Viessmann and Alpha — none of them pay us commission and we don't push a "boiler of the month".
Underfloor heating red flags
UFH failures usually trace back to design shortcuts, not the pipe. Ask these before you commit.
- Have you done a room-by-room heat-loss calculation?
- What pipe centres are you using and why? (Should be 150–200mm for boiler, 150mm for heat pump)
- Does the manifold have flow meters on every loop for balancing?
- What insulation are you laying under the pipe? (Should be 100mm+ under screed)
- Are the pipes and manifold from a full-system manufacturer with warranty? (Not mixed generics)
- Will you provide a commissioning certificate and balance report?
- Have you notified Building Control?
- Is my chosen floor covering compatible with UFH output?
Our promise on this job
Flat £50 diagnostic — deducted in full from any work booked. Fair, transparent quote before we start. If we can't fix the fault we diagnosed, we refund the diagnostic. All gas work is signed off by a Gas Safe registered engineer.
Talk to KJ about underfloor heating installation
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