Everbuild AC95 Intumescent Acoustic Sealant

Everbuild AC95 Acoustic Sealant | 900ml

AC95 is an intumescent acrylic sealant and adhesive formulated for acoustic sealing and bonding of plasterboard and kraft-lined insulation boards. It forms a permanently flexible, fire-rated acoustic barrier — tested to BS 476 Part 20 / EN1366-4:2006 with up to 5 hours fire resistance, and acoustic rated to BS EN ISO 140/3. It is also tested for air permeability to EN13141-1.

AC95 is used throughout acoustic floor, wall, and ceiling assemblies to seal flanking paths — gaps, perimeter joints, and penetrations that would otherwise bypass the acoustic treatment and significantly reduce overall performance. Each 900ml cartridge provides approximately 32 linear metres of coverage at a 6mm bead diameter. Requires a jumbo sealant gun for application.

Applications

• Acoustic floor assemblies — seal the perimeter gap between the floating floor and the wall, and any gaps between floorboards, before and after installation of the finish floor covering. Flanking paths at floor-wall junctions are a primary cause of underperformance in acoustic floor systems.
• Wall and partition assemblies — seal gaps between plasterboard sheets, at wall-floor and wall-ceiling junctions, and around any penetrations through the partition. Can be used as an adhesive to bond plasterboard to plasterboard, timber or metal studding, and direct to blockwork.
• Ceiling assemblies — seal perimeter joints and any gaps in the ceiling build-up. For overhead boarding applications, always use in conjunction with mechanical fixings.
• General acoustic sealing — suitable for sealing gaps in drylining applications and bonding most kraft-lined insulation boards. Forms an acoustic and intumescent barrier wherever gaps exist in a soundproofing assembly.

Product Benefits

• Up to 5 hours fire resistance. Tested to BS 476 Part 20 / EN1366-4:2006 — 25% greater fire resistance than conventional fire-rated sealants. Suitable for fire-rated acoustic assemblies where both acoustic and fire performance must be demonstrated.
• Acoustic rated to BS EN ISO 140/3. Independently tested for acoustic performance, making it a specifiable product for acoustic assemblies requiring documented performance data.
• Permanently flexible — movement accommodation ±7.5%. The cured sealant remains flexible, accommodating low to medium structural movement without cracking or losing seal integrity. Shore A hardness of approximately 40.
• Adheres to most surfaces. Bonds to plasterboard, timber, metal studding, blockwork, and most kraft-lined insulation boards. Not suitable for use against bituminous materials.
• Mould resistant, non-flammable, over-paintable. Suitable for use in habitable spaces. Over-paint once fully cured — typically 24 hours, up to 4–5 days in cold or humid conditions.
• 32 linear metres per cartridge. Coverage based on a 6mm diameter bead. 900ml cartridge requires a jumbo sealant gun.

Application

Ensure all surfaces are clean, dry, and free from dust, loose coatings, and old sealant. Highly porous substrates such as new plaster should be primed with Everbuild PVA Bond diluted 1:4 with water. Surfaces may be slightly damp but not wet — damp conditions will extend cure time. Do not apply below 5°C.

As a sealant: cut nozzle slightly larger than the gap to be sealed. Apply to gap, slightly overfilling, and finish smooth with a caulking tool or filler knife. Clean up excess with a damp cloth within 30 minutes.

As an adhesive for direct bonding to large surfaces: cut nozzle to provide a 9–10mm bead. Apply a continuous bead to one surface at 250–350mm centres. Apply board immediately and tamp down. Provide temporary support until cured.

As an adhesive for bonding to studding: apply a continuous bead to studding and apply board immediately. Do not apply more than one board’s width of studding at a time. Provide temporary support until cured.

Technical Details