Installing Celotex XR4000 PIR insulation in a rural new build development
With over 20 years of experience developing bespoke residential properties, Resolution Homes has built a reputation for architectural distinction and quality finishes. For co-owners Carl Porter and Eddie Lawley, quality is something they take personally.
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Start your U-value calculationUsing Celotex XR4000 PIR insulation to help achieve part L thermal compliance on a six-home new build site in Westcott
| Products Used: | Celotex XR4000 |
|---|---|
| Sector: | Housing |
With over 20 years of experience developing bespoke residential properties, Resolution Homes has built a reputation for architectural distinction and quality finishes.
For co-owners Carl Porter and Eddie Lawley, quality is something they take personally. From securing the land to selecting the final fixtures, they stay closely involved at every stage. The result is homes that balance thoughtful design with solid, real-world performance.
On a scenic plot near Waddesdon Manor, they have created six high-specification properties where thermal performance is as important as architectural design.
They selected Celotex XR4000 PIR insulation to help achieve consistent thermal performance across all properties. We visited the plot to see how this choice supports their commitment to building homes designed to last.
How Resolution Homes selected a PIR insulation product for Part L compliance
Nick Higgs, who brings merchant sector experience to his role as Operations Manager at Resolution Homes, explains the value of trusted products when specifying: “From a merchant's perspective, Celotex is a name that resonates with building control and inspectors. It might not always be the cheapest on the list, but it's a product that continues to be specified because of its proven performance. You know what you're getting, and that reliability really counts when you're working across multiple plots.”
Beyond brand recognition, Celotex proved a practical choice for the way Resolution Homes approaches quality-focused developments. With consistent thermal performance needed across all six properties, the team prioritised products with reliable supply and proven performance.
Strong technical support further reinforced the decision. While managing multiple plots simultaneously, having product guidance and performance data readily available makes it helpful in supporting timely progress toward thermal targets.
Using Celotex PIR floor insulation for six energy-efficient homes
Located in a picturesque rural setting, Westcott is described by Carl as "one of the cleanest, flattest sites we've worked on in years."
The development consists of four semi-detached and two detached properties, built to Resolution Homes' exacting standards. The homes feature open-plan kitchen/diner layouts with studies and utility spaces, designed for modern family living.
Built against a backdrop of woodland with views towards Waddesdon Manor, these properties offer premium living with the thermal performance today's buyers expect.
“We're building homes to last,” says Carl. “Getting the specification right now means fewer problems later, for us and for the people living in them.”
With building regulations tightening and buyers increasingly focused on long-term running costs, the team knew they needed a product that could meet the specific U-value targets required by the building design.
At design stage, the insulation strategy was developed to exceed the thermal performance targets set out in Part L. The ground floor was specified to achieve a U-value of 0.14 W/m²K—supported by Celotex XR4000 PIR insulation—and was approved through SAP and BREL modelling ahead of installation.
Using PIR insulation for consistent performance in multi-plot builds
Product reliability was critical when delivering consistent quality and thermal performance across multiple units.
The 532m² of Celotex XR4000 insulation installed beneath the ground floor screed across all six plots needed to perform consistently, with no variation in quality or installation challenges.
“We've used other PIR boards in the past that bowed under screed,” notes Nick. “That's not something you want to deal with when you're managing multiple plots. With Celotex, we have more confidence in the quality of the product.”
The logistics of supply also played a role in the decision. On a site like Westcott, the team needed assurance that materials would be available when needed. As Nick explains: "The volume of insulation required meant we had to split the order across multiple deliveries. Having confidence in availability and delivery scheduling helped keep the project moving forward."
Planning for Future Homes Standard with PIR insulation
Resolution Homes is keeping a close eye on the shifts reshaping UK housebuilding, from tougher regulations and rising material costs to the looming introduction of the Future Homes and Buildings Standard. Celotex XR4000 at the correct thickness can achieve the required U-value for the ground floors, supporting a smoother approval process with SAP assessors and inspectors.
For small developers working with tight margins, that's a balancing act. Products need to work hard, not just thermally, but practically too.
"When your reputation is your name, every home you build reflects directly on you," says Eddie. "That means the specification matters because someone's going to live there, and it's got to work." That's why insulation choices are becoming more strategic. With PIR products like Thermaclass Cavity Wall 21—plus a wider suite of cavity wall options now being pushed to market—developers can start building now to the standard that's coming.
It's not just about what meets regulations today. It's about being ready for what's next. And regional housebuilders like Resolution Homes are turning to Celotex to help them do that.
Want to learn about the benefits of using Celotex PIR insulation in your next build? Speak to the Celotex Technical Team for U-value calculations, product guidance and support to keep your project moving.
