Why CPS
At a glance: Our CPS (Closed Panel System) delivers the best overall balance of speed, performance and assurance:
- Fastest to watertight: factory-fitted membranes/service zone; fewer follow-on trades than SIP.
- Lower U-values: walls typically 0.13–0.15 W/m²K without insulated plasterboard.
- Greener insulation: hydrophobic blown recycled glass-wool (non oil-based) vs SIP’s PUR/PIR.
- Assurance: BOPAS + BBA, 60-year durability guidance; fully mortgageable.
- Architecture: deeper wall cavity reduces cold bridging and improves proportions/spans.
- Cost: a larger crane is required compared to SIP, adding to erection costs, making SIP the better option for some remote or challenging sites
System Comparison
| Feature | CPS (Closed Panel) | SIP (Structurally Insulated Panel) | Standard Timber Frame | Traditional Masonry |
|---|---|---|---|---|
| U-values (walls) | 0.13–0.15 W/m²K as standard; no insulated PB required. | ~0.16–0.21 W/m²K; often needs insulated plasterboard to match CPS. | Typically 0.18–0.22 W/m²K unless upgraded. | Often 0.25+ W/m²K unless thick, costly cavities used. |
| Speed to watertight | Fastest — factory membranes/service zone; minimal follow-on trades. | Fast shell (5–7 days) but more internal follow-on trades before true weathertightness. | Slower — open panels require site membranes, insulation, service battens. | Slowest — weather-dependent, long programmes. |
| Accreditation & warranty | BOPAS + BBA, 60-year durability guidance; lender friendly. | BBA typical; BOPAS varies by supplier; lenders can be cautious. | Accepted with NHBC/equivalent warranty. | Universally accepted; no inherent system warranty. |
| Insulation & sustainability | Recycled glass-wool (mineral, non oil-based), hydrophobic; deep cavity. | PUR/PIR rigid foam (oil-based, higher embodied carbon). | Mineral wool fitted on site (quality varies). | Mineral wool/cavity fill; risk of gaps/cold bridges. |
| Cold bridging | Minimal — double-stud breaks thermal bridges. | Joints/edges need tapes/VCL; bridging at interfaces. | Notable around studs and junctions. | High through lintels/block-to-block paths. |
| Factory fitting | External membrane pre-fitted; service void ready for 1st-fix. | Internal VCL + service battens fitted on site. | Most membranes/voids installed on site. | N/A — relies on site workmanship. |
| Follow-on trades | Fewer — quicker critical path to M&E first-fix. | More — VCL, service battens, insulated PB usually required. | More — insulation, membranes, service void done on site. | Most — wet trades throughout. |
| Architectural flexibility | Deeper cavity enables better proportions and spans; excellent for large reveals. | Good, but internal service zone often added later. | Flexible but performance drops without thicker walls. | Very flexible; slower and heavier. |
| Programme & prelims | Shortest — faster to watertight reduces prelim costs. | Short shell but longer follow-on period. | Longer overall due to site works. | Longest; high prelims. |
| Mortgageability | Strongest case with BOPAS/BBA + 10-yr warranty. | Generally acceptable with 10-yr warranty; varies by lender. | Accepted with mainstream warranties. | Universal. |
Action Points
- Read CPS Explained for full technical detail and warranties.
- Compare with SIP (what extra trades are needed to match CPS).
- Check lender comfort (BOPAS-backed systems, stage payments).
Other sustainability pages
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