1 · Detail design with EWS1 surveyor

For Building Safety Fund and Cladding Safety Scheme remediation work, the detail design references the appointed EWS1 surveyor's required materials schedule. CleverBloom coordinates with the surveyor on the Spacetherm A1 specification — confirming A2-s1,d0 certification, BBA references, and fire-class continuity with the main EWI line (STO Therm Mineral K). The materials schedule is locked before site work begins.

2 · Cut to size on site

Blanket cut with a craft knife or sharp scissors to reveal width — typically 100–150 mm strip per reveal jamb. The mineral fibre carrier is slightly stiffer than the Class C blanket; cutting releases minor aerogel dust, installer wears a dust mask and vacuums debris. Cut edges hold their geometry well in the fire-modified mineral carrier.

3 · Adhered with Proctor A1-compatible adhesive

Spacetherm A1-compatible adhesive applied to the substrate; the aerogel blanket pressed in. Standard reveal-correction work uses Proctor's matched A1-compatible cementitious adhesive (not the Class C blanket's standard adhesive — different chemistry, different fire-spread behaviour). Joint tape at every panel-to-panel edge for continuous coverage.

4 · Reinforcing mesh + base coat

After the blanket is bonded and tape-jointed, an alkali-resistant glass-fibre reinforcing mesh is bedded into a cementitious base coat across the reveal surface. The mesh + base coat creates the substrate for the finish render coat above — typically matching the main STO Therm Mineral K render system specification for visual continuity.

5 · Finish render

Finish render coat applied across the reveal in the same system as the main wall plane — STO Silco K, Silikat, or matched system per the project's render specification. The reveal finish matches the main external wall surface; no visible joint or material transition. The aerogel layer is entombed behind the render for the life of the EWI system.

6 · EWS1 certification pack

Project handover includes the A2-s1,d0 EN 13501-1 fire test certificate, BBA reference, photo log of every reveal install at sample positions, materials-schedule sign-off from the EWS1 surveyor, and ψ-value reduction documentation for the reveal junctions. Pack format aligned with Building Safety Fund and Cladding Safety Scheme audit requirements.

Silica aerogel core

Same Aspen Aerogels chemistry as the Class C blanket — nano-porous silica that's 90%+ air by volume, with pores smaller than the mean free path of air molecules at room temperature. Trapped air can't convect; heat conducts only by the silica matrix and by radiation, both slow processes. The ultra-low thermal conductivity is intrinsic to the aerogel structure.

Mineral fibre carrier (fire-modified)

Where the Class C Aerogel Blanket uses a polyester non-woven carrier, Spacetherm A1 uses a mineral fibre carrier matrix with reduced organic binder content. The mineral fibre carries the aerogel through fire conditions without contributing combustibility; the reduced binder ensures the assembly tests A2-s1,d0 under EN 13501-1 fire testing. The λ trade-off (0.020 vs 0.015) comes from the fire-modified carrier, not the aerogel core.

Aspen Aerogels Spaceloft A2

Manufactured by Aspen Aerogels at the Northborough, Massachusetts facility under the Spaceloft A2 brand line. UK supply through A. Proctor Group (Stirling, Scotland) — Proctor is Aspen's primary European architectural distributor. The chemistry has been in service across European mid-rise residential and commercial fire-critical applications since the post-Grenfell regulatory tightening.

Hydrophobic silica

The silica matrix is treated to be hydrophobic during manufacture — same as the Class C blanket. Water sits on the surface and runs off; incidental water exposure (driving rain during install, condensation on adjacent surfaces) leaves the λ unchanged. Important in reveal applications where water tracking from window flashings is part of normal service.

Fire: A2-s1,d0

Tested to EN 13501-1: classification A2 (limited combustibility), smoke production s1 (very low smoke), flaming droplets d0 (no droplets). Meets Approved Document B Regulation 7(2) requirements for materials in external walls of buildings with a top storey over 11 m. Some manufacturer marketing uses "A1" terminology colloquially; the formal test classification is A2-s1,d0, which is the practical equivalent for AD B Reg 7(2) compliance.

Vapour-permeable

Water vapour resistance factor remains in the same range as the Class C blanket — vapour-permeable, won't trap moisture in the assembly. Suitable for breathable build-ups and where vapour-open materials are required by the project specification (Listed Building applications inside the over-11 m EWS1 context, heritage façades on mid-rise commercial conversions).

50+ year design life

Aspen Aerogels publishes a 50+ year design life for Spaceloft A2 chemistry in standard architectural service. The silica matrix is chemically stable; the mineral fibre carrier doesn't degrade; the hydrophobic treatment doesn't wash out. Once installed and finished behind the render, the blanket performs for the life of the EWI system.

No annual service required

No moving part, no electrical component, no consumable. Behind the render, the aerogel is entombed for the life of the building. Standard EWI inspection cadence applies — visual review of render condition every 10–15 years, with any required local render remediation handled by EWI specialist trade. The Spacetherm A1 layer below isn't disturbed by render maintenance.

Doesn't degrade with water exposure

Hydrophobic silica chemistry means incidental water exposure (driving rain during install, condensation on adjacent flashings, occasional water tracking from window head details) leaves the λ unchanged. The blanket dries out and continues performing. This is what makes it suitable for reveal applications where occasional water exposure is part of normal building service.

EWS1 documentation retention

For Building Safety Fund-funded remediation, the EWS1 certification pack must be retained for the life of the building — passed to subsequent owners, mortgagees, and EWS1 surveyors at re-survey. CleverBloom issues two physical copies of the handover pack and one digital archive copy; the asset owner retains the master file for transfer at sale or refinance events.

Window replacement penetration discipline

After EWS1 remediation completion, every window replacement programme that affects the reveal must use matched A1 reveal correction (Spacetherm A1 offcuts or new spec) to maintain the verified envelope. CleverBloom retains client offcuts and provides spec guidance for future window programmes — without this discipline, a single window-replacement cycle can compromise the EWS1 declaration.

Fire-class continuity across the wall

The Spacetherm A1 reveals only deliver their AD B Reg 7(2) compliance if the main EWI scope (STO Therm Mineral K) is intact and certified to the same standard. Any future remedial work on the EWI wall plane must maintain the A1 chain end-to-end — no substitution of cheaper materials, no compromise on the certification trail. CleverBloom flags this on every handover document.