Simpson End Seal

Airtight, Acoustic and Fire-Rated Joist Pocket Solution for Masonry Walls

The Simpson Strong-Tie SES End Seal is a high-performance joist end treatment designed to reduce air leakage, sound transmission, and fire risk where timber joists penetrate pocket masonry walls. Engineered to simplify compliance with Building Regulations Part L, Part E, and Part B, the SES provides a fast, effective alternative to traditional mastic sealing—offering a secure and clean finish around joist ends.

Key Features

• Reduces Air Leakage
  Designed to seal gaps around joists embedded in block walls, the SES eliminates the need for mastic sealant, provided mortar bedding is applied with good workmanship.

• Improves Acoustic Performance
  Meets the sound insulation requirements of proprietary joist caps as specified in Appendix A of the Robust Details Part E Handbook, reducing airborne and impact sound transmission.

• Fire-Resistant
  Provides up to 1 hour fire resistance in accordance with Approved Document B, enhancing passive fire protection at joist ends.

• Full Joist Bearing Support
  Allows for 100mm of joist bearing on masonry, ensuring a structurally sound and regulation-compliant installation.

• Easy and Secure Fixing
  Secured in place using 30mm square twist nails, offering fast, reliable on-site application without adhesives or sealants.

• Durable Material
  Manufactured from pre-galvanised mild steel, delivering corrosion resistance and mechanical protection within cavity or solid masonry walls.

Benefits

• Complies with Multiple Building Regulations
  Helps meet requirements under:

  • Part L: Reduced air leakage

  • Part E: Sound insulation

  • Part B: Fire protection

• Cost-Effective and Time-Saving
  Eliminates labour and material costs associated with applying mastic sealant around every joist end.

• Suitable for External and Party Walls
  Versatile application for both perimeter and internal masonry walls—ideal for separating dwelling units or insulating external wall junctions.

• NHBC Approved
  Meets the NHBC Technical Requirements, ensuring full regulatory compliance on NHBC-insured sites.

Material Specification