ArmaFlex and foil-faced PIR boards solve different fitting problems. Flexible foam can follow curves; rigid boards suit flatter areas. The right choice depends on the exact material, the van structure and how the whole build manages heat and moisture.
This is a research comparison, not a road test or a manufacturer-approved van installation design. Neither brand name alone proves that a particular product is suitable for your vehicle.
The practical difference
| Decision | Flexible elastomeric foam | Foil-faced PIR board |
|---|---|---|
| Shape | Can follow curves and irregular panels | Needs cutting to fit flat areas |
| Space | Available in several thicknesses; check the exact range | Check the board thickness against the actual cavity |
| Joints | Requires the specified adhesive and joint treatment | Requires a suitable fixing and joint design |
| Buying | Check the precise ArmaFlex range, sheet size and adhesive | Check the precise board range, facing and handling instructions |
| Overall result | Depends on continuity, fitting and the surrounding build | Depends on continuity, fitting and the surrounding build |
Compare the actual product, not just the brand
Armacell describes AF/ArmaFlex as a flexible, closed-cell elastomeric foam with high resistance to water-vapour diffusion. Its technical data varies by thickness and temperature. That description does not mean that every finished installation is completely vapour-proof.
Soprema now lists the former Celotex GA4000 range as SOPRATHERM GA4000. It is foil-faced rigid PIR board intended for defined building applications. Building certification should not be treated as approval for an arbitrary vehicle installation. Check the current product identity and ask the supplier about your intended use.
Compare like with like: thickness, declared conductivity, test conditions and the intended application. Avoid treating one quoted laboratory number as a prediction of the temperature inside your van. Windows, exposed metal ribs, gaps, ventilation and occupancy all change the result.
Condensation needs a whole-build plan
Insulation does not remove the water generated by breathing, cooking or wet clothing. A small gap can let moist air reach colder metal even when the material itself resists vapour. Neither foam nor foil tape guarantees a dry vehicle.
Before covering the panels, decide how you will ventilate, dry wet kit, inspect vulnerable areas and deal with existing leaks or corrosion. Keep vehicle drainage paths and service access clear. If the build is already damp, diagnose the source before adding a lining over it.
Avoid advice that promises condensation will harmlessly drain away behind an insulation layer. Hidden moisture needs investigation. For a complex build, have the moisture and ventilation design reviewed by a competent conversion specialist.
Installation details worth checking
Do not choose an adhesive from a generic shopping list. Confirm compatibility with the exact insulation, paint and substrate, and follow the manufacturer's current application and curing instructions. Check the safety data and ventilation requirements before working inside the van.
Armacell's application manual explains adhesive joint sealing and material-specific installation techniques. Read the section that applies to your product and application; pipe-insulation examples are not a complete van conversion specification. Do not replace the specified joint technique with an assumed overlap or a random foil tape.
For rigid boards, plan a fit that avoids loose pieces, rattles and unplanned voids. Check how boards will be retained when the vehicle moves. Follow the supplier's cutting, dust-control and storage guidance. Do not assume a construction foam or adhesive is appropriate merely because it fills a gap.
For either approach, keep the insulation system clear of heat sources unless its instructions explicitly permit the proposed clearance. Material fire classifications are not a fire-safety approval for the finished campervan.
Budget the complete system
Measure your own van rather than using a universal coverage figure. Draw the roof, walls and doors, allow for cutting waste, and check the thickness left for linings and furniture. Include adhesive, joint materials, fixings, protective equipment and delivery in the comparison.
Prices change, so this guide does not quote a current retailer price. A cheaper sheet can become a more expensive installation if it creates excessive waste or needs additional preparation. Compare complete installed options for your own layout.
A sensible decision process
- Measure the spaces and identify curves, access points and exposed metal.
- Shortlist exact product codes and read their current technical and safety documents.
- Confirm suitability for the proposed vehicle application with the supplier or installer.
- Design joints, ventilation, service access and moisture control together.
- Trial a small area before committing to a full purchase or covering the entire van.
Flexible foam is worth investigating where close fitting around curves is the priority. Rigid PIR is worth investigating for flatter spaces where it can be secured appropriately. A mixed approach needs a coherent joint and moisture design too; combining two materials does not automatically combine all their benefits.
Sources and further reading
- Armacell AF/ArmaFlex technical specifications
- Armacell ArmaFlex application manual
- Soprema SOPRATHERM GA4000 product information
Technical sources checked on 24 October 2026. Check the document for the exact product supplied before buying or installing it.
