Insulating Above a Groundbearing Slab – Sitework

Floor Insulation

Points To Watch

Under the screed

  1. Top slab with sand or grid off rough spots
  2. Insert vertical edge insulation.
  3. Lay Ballytherm boards to cover the surface of the floor as in a broken bond pattern.
  4. Lay Ballytherm boards with VCL/slip sheet and make sure that joints are joined and sealed.
  5. Lay down the screed.

Procedure to install beneath sheet flooring

  1. Lay slab with sand or grind rough spots down.
  2. Insert timber battens to fit at thresholds and a high loading spots.
  3. Put Ballytherm boards to cover top of the floor using a broken bond pattern.
  4. Lay with VCL/slip sheet and lap and seal joints.
  5. Install sheet flooring.


  • Carefully fit boards to ensure a tight fit.
  • Cover all service holes with a sealant.
  • Be sure that sealed service holes are sealed before laying down the screed.
  • Protect Ballytherm boards from traffic when laying screed or flooring.
  • Protect Ballytherm boards that have been exposed when levelling the screed.


Need Advice?

More information can be obtained about Ballytherm thermal insulation for above ground-bearing slabs by contacting one of our technical advisors at 0800 644 6900, or by email us at

Floor Insulation


Design Guidance