Insulation Below Suspended Timber Floors – Sitework

floor insulation


  1. In floor insulation, install timber battens to sides of joists*.
  2. Cut boards to allow them fit into the space between joists and place boards on battens for floor insulation before putting on deck
  3. Spread out and install timber flooring.

* The space at the battens top to the joists top will depend on the Ballytherm board thickness and on a service hole specified by the installation plans.


  • Measure service void or hole before cutting Ballytherm boards to ensure a close cover.
  • Pack insulation heavily in areas between perimeter joists and wall to prevent thermal escape.
  • Cover all service hole with a flexible material.

Extending your home or starting a new building project needing thermal insulation underfoot? For more information about Ballytherm insulation products for suspended and other floors, contact us at 0800 644 6900, or email us at

Floor Insulation


Design Guidance