Reality Check · August 2026
Underfloor Heating Systems Compared – Screed vs Overlay vs Structural Boards
Public prices for the main system paths, floor-height reality in older South West properties, and how our calculator maps each option.
Quick Answer
Screed systems are usually the cheapest route when the floor is already open or you are building new. Overlay boards cost more per square metre but avoid digging up existing floors and keep the height rise low. Structural boards sit higher still when the floor itself needs to carry load.
Public prices reflect this. Screed work often lands £50–£90 per m² installed when conditions are good. Overlay systems commonly sit £80–£150 per m². The calculator uses these ranges as the starting point and then applies realistic figures for the height limits, transitions and older floors that are common in Devon and Cornwall. That is why the bands are set where they are.
What public prices show
| System path | Typical installed £/m² | Typical build-up | Best for |
|---|---|---|---|
| Screed (new-build / open floor) | £50–£90 | Insulation + 50–65 mm screed | New builds, deep renovations, highest thermal mass |
| Low-profile overlay (XPS / gypsum) | £80–£150 | 15–30 mm boards | Height-limited retrofits, solid floors |
| Suspended / joist (plates or boards) | £70–£130 | Minimal rise between joists | Timber floors where boards can be lifted |
| Structural / 22 mm chip or OSB | Higher end of overlay range + | Load-bearing board thickness | When the floor itself needs structural capability |
Material-only prices for XPS or chipboard boards are significantly lower. Full system prices include pipe, manifold, labour, insulation, edge strips and finishing. Online board prices alone are never the installed cost.
Floor height reality in Devon & Cornwall
A traditional screed system needs insulation plus 50–65 mm of screed cover. Many older properties in the region simply do not have that headroom without major disruption to doors, thresholds, staircases and adjoining floor levels.
This is why low-profile overlay systems (15–30 mm) and structural board paths exist. They cost more per square metre than a simple screed on an open floor, but they are often the only practical route on occupied renovations or period floors. The higher public price ranges for overlay and structural systems reflect this reality, not over-pricing.
In new builds or full gut renovations where the floor is open, screed remains the strongest and usually lowest-cost path — and the best thermal match for a heat pump because of its high mass.
How the calculator maps each path
Our UFH calculator offers the same system families that appear in the public price data:
- Traditional screed — lowest cost and highest thermal mass when height allows
- Overlay (XPS / gypsum style) — low-height retrofit path
- Structural / load-bearing boards — when the floor itself needs to span or carry load
- 22 mm chip / MDF or plain board paths — timber-floor options where boards can be lifted or replaced
The planning bands already start from realistic public material and labour ranges and then apply conservative allowances for the floor-height, access, transition and finishing realities that are common on older South West properties. The calculator does not undercut the public figures — it builds the full installed planning number from them so the figure remains useful and survives a proper survey.
Why the calculator sets the numbers here
Online board prices and simple supply-only kits are useful for understanding the material slice. They are not the installed cost. A complete system also includes pipe, manifold, actuators, controls, insulation, edge detailing, labour, and the practical work of dealing with thresholds, doors and adjoining floors.
The calculator therefore prices the full installed planning figure for each system path. It is deliberately set as a realistic early-stage band rather than the absolute lowest kit-only headline, so the number does not fall apart once a proper survey is done on an older Devon or Cornwall property.
South West notes
Period terraces, solid-wall cottages and many village properties frequently force the overlay or structural routes because of limited floor height. New builds, extensions and full renovations where the floor is open can take the lower-cost screed path and gain the thermal-mass advantage that works so well with heat pumps. Access, small rooms and awkward transitions can also push a job toward the higher end of the public ranges once the survey is complete.
See the system paths for your own floors
The free underfloor heating Passport already maps screed, overlay, structural and 22 mm paths and applies the realistic planning bands. Useful when floor height is limited — common on older properties across Devon and Cornwall. No obligation. Every submission is personally reviewed.
Get realistic numbers for your floors →Frequently asked questions
Is overlay underfloor heating more expensive than screed?
Usually yes on a pure materials and installed cost per m² basis. Overlay systems cost more because the boards themselves are more expensive, but they can be the only practical option when floor height is limited. Screed is typically the lowest-cost path when the floor is open.
How much does underfloor heating cost per m² in 2026?
Public installed prices typically sit at £50–£90/m² for straightforward screed or new-build paths and £80–£150/m² for low-profile overlay or structural retrofit solutions. Material-only board prices are significantly lower but do not include pipe, manifold, labour or finishing.
Why does floor height matter so much?
A traditional screed system needs 50–65 mm of depth plus insulation. Many older Devon and Cornwall properties cannot accommodate that without major disruption to doors, thresholds and floor levels. Low-profile overlay or structural board systems become necessary and sit at the higher end of public price ranges.