Some UFH projects are straightforward. Others evolve over months – and sometimes considerably longer.
We were delighted to get on site at this stunning family home extension renovation in the rolling Leicestershire countryside.
We were first approached to quote this in early 2025. Since then, the plans have changed, the design has developed and the project has moved through several stages.
Our job has been to work alongside the client, their building contractor and other parties throughout, adapting the UFH design as the building itself has evolved.
Starting from the ground up
For the substantial 213m2 ground floor, the homeowner opted for a complete floor excavation across the footprint of the property.
That meant this wasn’t a retrofit project where we needed to work around an existing floor. With the floor being dug out as part of the wider renovation, there was an opportunity to install a traditional pipe-in-screed UFH system, designed from the ground up around the new floor construction.
It also allowed the UFH design to be considered alongside the insulation, floor build-up, room layouts and heating requirements, rather than being added as an afterthought.
Digging out the sub-floor isn’t always necessary in a renovation with countless retrofit overlay options available to suit different scenarios.
Excavating an existing floor can provide more flexibility over insulation, floor build-up and UFH performance, but it also brings additional excavation, disposal and construction costs, so the cost/benefit needs to be carefully weighed up.
Designed around the building
The CAD design shows how the pipe spacing changes across the property.
In the new 70m2 extension on the right side of the property, the pipework is installed at 100mm centres, while the existing areas use 150mm centres.
It’s not simply a case of using the same spacing everywhere. The design considers the individual requirements of each area, including the large, full-height vaulted space and substantial gable-end window in the extension.
Where heat demand is higher, closer pipe spacing can help deliver the required output while maintaining an appropriate operating temperature. Cozia’s design team works with heat loss calculations provided by heating engineers, to ensure our UFH systems deliver heat outputs that meet calculated losses for the relevant floor covering.
Good UFH design isn’t about putting pipe in the floor. It’s about putting the right amount of pipe, in the right place, at the right spacing.
Designed to complement the Air Source Heat Pump
The property is being heated by an air source heat pump (ASHP), making the relationship between the UFH design and the heat source particularly important.
Heat pumps work most efficiently when they can operate at lower flow temperatures and run steadily for longer periods – the perfect complement to underfloor heating. The UFH system therefore needed to be designed to work in synergy with the heat pump, with appropriate pipe spacing, circuit lengths, flow rates and zoning.
Getting this wrong can compromise performance, increase short cycling and make it harder for the heat pump to operate as efficiently as it should.
This is why we shouldn’t treat UFH design as simply a product specification. The floor, the building and the heat source all need to work together.
With the pipework fixed, and a successful pressure test undertaken for each manifold, we poured around 12m3 of screed to complete the ground floor UFH install. Within 24 hours, the builder and other trades were back on site continuing their renovation work, using boards to spread any point loads such as ladders and platforms, whilst the screed cures to full strength.
The chosen screed formulation will also mean less expense and work to the screed surface before the flooring contractor installs the client’s chosen coverings.
An evolving project
This is only the first phase. After working with the contractor through the various design changes and developments, we’ve just completed the ground floor installation, but we’ll be back shortly for the next stage.
The first floor will use an insulated overlay system, bringing a very different set of design considerations to the same property.
→ Keep an eye out for Phase 2: Insulated Overlay on the First Floor.
