Expandafoam Self Adhesive - Technical Details and Specifications

Product Overview

Expandafoam SA is the self-adhesive variant of Expandafoam, a closed-cell polyethylene joint filler designed for construction applications requiring a readily compressible and low load transfer joint filler. The self-adhesive backing feature facilitates easier installation without requiring additional construction adhesive.

Material Composition and Properties

Expandafoam SA is manufactured from closed-cell polyethylene foam, providing essential performance characteristics for joint sealing applications. The material exhibits the following key properties:

• Nominal Density: 25 kg/m³, contributing to its lightweight and compressible characteristics
• Form: Compressible, closed-cell polyethylene foam rod
• Colour: White
• Water Absorption: 0.01 ml/cm³ (minimal water absorption)
• Service Temperature Range: Minus 80°C to 100°C
• Weathering Test: No disintegration confirmed
• CFC Free: Manufactured without chlorofluorocarbon compounds

Advantages and Key Features

Expandafoam SA offers multiple performance advantages for construction applications:

• Readily Compressible: Easily compressed during installation to ensure proper fitting
• Low Load Transfer: Minimizes stress transfer to adjacent building materials
• Self-Adhesive Backing: Optional feature available on Expandafoam that facilitates installation without requiring additional construction adhesive
• Compatible with Elastomeric Sealants: Works effectively with all elastomeric sealants
• Non-Gassing: Does not release volatile compounds
• No Water Absorption: Prevents water ingress and provides durability in wet conditions
• No Migratory Chemicals: Contains no migratory chemicals that could adversely affect joint sealants
• UV Resistance: Not suitable for long-term UV exposure; suitable for protected applications
• Rot-Proof: Ensures long-term durability

Available Sizes and Supply

Expandafoam SA is available in a specific size configuration optimized for various applications:

• 75mm x 10mm x 25m roll

This dimensional specification accommodates common joint widths and provides sufficient roll length for medium to large-scale applications.

Application Guidelines

Installation Method

Expandafoam SA should be installed with 25% compression during fitting to ensure that applying the joint sealant will not displace the foam. The self-adhesive backing eliminates the need for separate construction adhesive, streamlining the installation process.

Joint Configuration

When properly compressed, Expandafoam SA assumes an oval cross section, with the depth of the foam being greater than the nominal joint width. The circular section of the foam provides a convex face to ensure that applied elastomeric sealants are given optimum shape for minimum strain as the joint moves.

Sealant Depth Requirements

Expandafoam SA must be positioned to accommodate the required sealant depth of minimum 6 mm at the thinnest section of the sealant bead (above the centre of the foam), with a minimum bonding depth at the joint face of 6 mm on smooth glass and metal surfaces, and 12 mm on porous or rough surfaces.

Limitations and Restrictions

Expandafoam SA has specific application limitations:

• Not suitable for hot pour sealants: The material is incompatible with heat-applied joint sealants
• Not resistant to long-term UV exposure: Should not be used in applications subject to prolonged direct sunlight
• Not suitable for heavy loads: Applications where joint backing must provide continual support for the joint sealant (such as water-retaining structures or floor joints subject to traffic) require alternative products like Hydrocell or Stiffjoint

Joint Application Areas

Expandafoam SA is used effectively in multiple construction applications:

• Expansion joints in brick and blockwork
• Isolation joints requiring low load transfer
• External walling and cladding as a gap filler and backing strip
• Glazing applications as a gap filler to support perimeter sealing
• Internal finishes including partition joints and around work tops and other fittings
• Bridge decks and abutments as a bond breaker and support strip
• Concrete floors subject to foot traffic and light wheel loads

Design Criteria Considerations

When using Expandafoam SA, the following design considerations apply:

• The foam diameter should be selected based on joint width, typically 20-30% larger than the joint width to ensure proper compression
• Installation must avoid sharp objects that may damage the foam backing, as any damage can allow air voids to form in the sealant
• Correct fitting results in an oval cross section with depth greater than the nominal joint width
• The self-adhesive backing should provide adequate adhesion without additional fastening methods

References

• [1] Fosroc_Expandafoam_Closed_Cell_TDS.pdf
• [8] Fosroc_Expandafoam_TDS.pdf