Thermoguard Intumescent Mastic

Thermoguard Intumescent Acoustic Mastic is a one-part, acrylic-based sealant designed to expand under heat to form a fire-resistant char. Used to seal joints and openings around fire doors, window frames and service penetrations in floors and walls, it helps reinstate fire resistance and provides acoustic and air permeability benefits. Independently tested to BS and EN standards.

Fire Performance:

• • EN 1366-3:2009 (penetration seals)

  • EN 1366-4:2006 (linear joint seals)

• Tested With: Metallic pipes, cables, cable trays, cable bunches, and more

• Max Joint Size Tested: 490mm x 150mm

Refer to the full installation guide for specific configurations, performance tables, and fire-resistance ratings.

Surface Preparation

• Ensure joints, voids, and service openings are clean and free from dust, grease, and debris.

• Compatible with block walls, concrete, masonry, plasterboard, and more.

• Suitable for flexible and rigid walls and floors.

• Recommended: test adhesion on unusual substrates before full application.

Technical Data

• Density: 1.63 g/cm³

• Appearance: Paste, matt finish

• Shore A Hardness (after curing): 63/39

• Movement Capability: ≤ 7.5%

• Operating Temperature: -5°C to 40°C

• Longevity (Firestop Materials): 30 years

• Shelf Life: 18 months (from manufacture date)

• Acoustic Isolation: Up to 63dB (EN 10140)

• Air Permeability: 0.0/0.0 m³/h/m² @ 100Pa (EN 1026)

• Fire Classification: EN 13501-2

• Certifications: CE Marked, Certifire Approved, UL-EU Listed

Directions for Use

• Application Method: Gun or trowel sealant into joints or apertures, using backing materials as required (e.g., PE open-cell foam).

• Joint Widths: Suitable for gaps up to 50mm wide.

• Installation Conditions:

  • Rigid walls (≥100mm): Concrete/masonry ≥ 650kg/m³

  • Rigid floors (≥150mm): Concrete/masonry ≥ 650kg/m³

  • Flexible walls (≥100mm): Timber/steel studs with 2x 12.5mm Gypsum boards

  • Apply in internal conditions ≥85% RH (Type Z conditions per ETAG 026-3)

• Backer Rod: Use as depth gauge where required.

Data Sheets / Downloads

Thermoguard Intumescent Mastic - TDS

Thermoguard Intumescent Mastic - MSDS

Declaration of Performance (PS)

Declaration of Performance (LGS)

Certificate of Constancy of Performance