Resources / Underfloor heating
Best Underfloor Heating System for Renovations
There is no universal “best” product — only the best match for floor construction, height, disruption and heat source. Here is how to choose for Devon and Cornwall renovations.
Quick Answer
For most renovations that cannot dig out floors, a low-profile overlay (gypsum, XPS or similar) is the practical winner. Where floors are already open or new screed is planned, traditional pipe-in-screed still offers excellent thermal mass and heat-pump-friendly temperatures. Joisted upper floors need plates, overlays on the deck, or structural boards — not a wet screed on ordinary domestic joists without structural design.
Choose by construction → height → programme → heat source → system family. Brand is the last decision, not the first.
View printable checklist Planning aid — not a quote
Decision framework
| Your situation | Typical direction |
|---|---|
| Existing solid floor, minimal dig-out | Overlay gypsum / low-profile board system |
| Joisted upper floors | Between-joist plates / structural boards / deck overlay |
| New screed already in the build | Traditional pipe in screed |
| Heat pump planned | Any low-temp capable system with designed room output |
| Tight programme, rooms in use | Overlay — avoid long screed cure times |
| Full dig-out / extension slab | Screed often wins on cost per m² and mass |
More renovation context: UFH for renovations.
When screed is the better choice
Pipe in screed is still the reference system for new floors. Thermal mass smooths heat delivery; output at low flow temperatures is well understood; material cost per m² is often competitive when the floor is open anyway.
- •Extensions and new slabs
- •Full dig-outs where levels will change regardless
- •Projects that can wait for dry and cure before finishes
The renovation killer is time. Traditional cement screeds are often discussed with a rough “1 mm per day” drying rule of thumb — a 65 mm pour is a long wait. Liquid screeds can be thinner and quicker but still need a real programme, not a weekend.
If people are living in the rooms, screed is usually the wrong default — not the wrong technology.
When overlay is the better choice
Low-profile overlays exist for one reason: retrofit without destroying the house schedule. Gypsum-type systems, XPS boards and similar products add a thin heated layer on a prepared base.
- •Occupied homes and phased room-by-room work
- •Limited floor height at doors and stairs
- •Solid floors that are otherwise sound
Trade-offs: less thermal mass than a thick screed (faster response, less “flywheel”), stricter need for a flat base, and finishes must match the system’s output assumptions.
Full comparison: overlay vs screed.
Upstairs and joisted floors
Do not import ground-floor screed logic upstairs. Typical options:
- •Between-joist plates — pipe in aluminium plates, insulation in the void
- •Deck overlay — if finished height allows
- •Structural UFH boards — replace the deck where the project allows
Plate contact, insulation below the heated plane, and manifold routing decide performance. Detail: UFH upstairs renovation.
Heat pumps change the “best” test
The best renovation system for a heat pump is one that delivers design room output at a low flow temperature — not the one that can be cranked to 55°C to feel like old radiators.
- •Design output at the flow temperature you will actually run
- •Prefer steady controls over deep setbacks
- •Size the heat pump from heat loss, not from floor area folklore
A boiler can still drive UFH via blending. If plant is being replaced anyway, low-temperature UFH + heat pump is usually the cleaner long-term pair. See response times and heat-pump sizing guides.
Side-by-side (renovation lens)
| Factor | Screed | Overlay | Joist systems |
|---|---|---|---|
| Disruption | High if dig-out | Lower | Medium (access) |
| Programme | Cure time critical | Faster to finish | Depends on deck works |
| Floor height | Often more build-up | Low-profile options | Within joist or on deck |
| Thermal mass | High | Lower | Low–medium |
| Heat pump fit | Excellent if designed | Excellent if designed | Good if output meets loss |
| Best when… | Floor already open | Living in the house | Suspended timber floors |
Devon & Cornwall realities
- •Uneven historic slabs — overlays need a proper base; budget levelling
- •Low doors and ceilings — height often kills thick build-ups
- •Mixed construction — solid ground + joisted first floor in one project is normal
- •Solid stone / cob — floor heat will not fix a naked envelope
- •Oil / LPG to heat pump — UFH becomes part of a whole-house low-temperature plan
- •Conservation limits — floors are often freer to upgrade than external walls
Common mistakes
- •Picking a system from a brochure before measuring door heights
- •Assuming one product suits solid and joisted floors
- •Ignoring cure time on screed while the family stays in the house
- •Designing for high flow temperatures “just in case” on a heat pump job
- •Skipping manifold commissioning — then blaming the boards for cold spots
Cold spots diagnosis: causes and fixes.
Recommended sequence
- Map solid vs joisted rooms and level changes
- Measure height at doors, stairs and fixed joinery
- Decide programme and which rooms stay occupied
- Confirm heat source (boiler, heat pump, or both over time)
- Pick system family per floor type
- Design output at realistic flow temperature and finishes
- Price supply, prep, install and controls — then brand within that family
Honest bottom line
The best underfloor heating system for a renovation is the one that fits the floor you have, the height you can spare, the time you can live with, and the heat source you will run.
Overlay wins most occupied solid-floor jobs. Screed wins when the floor is open. Joist systems own the upper floors. Heat-pump jobs need low-temperature design, not a product that relies on turning the flow up. Everything else is detail.
Frequently asked questions
Is overlay always better for renovations?
It is the most common practical choice when people are living in the house and height is tight. If you are digging out anyway, screed can still be the better engineering and cost choice.
Which system is best with a heat pump?
Any system designed to meet room heat loss at low flow temperature. Screed, overlay and well-detailed joist systems can all work. High flow “to be safe” is the wrong optimisation.
Can I mix systems in one house?
Yes — solid ground floor overlay and joist upstairs is normal. Design each for its construction; share a coherent heat source and control strategy.
Should I choose the brand first?
No. Choose the system family from construction and programme, then a reputable product within that family that matches height and output needs.
Next step
Get a realistic planning band for your home, then use the checklist when you speak to installers.