Spray Foam Insulation

Insulation over insulation

WALLTITE® is applied directly to the ‘over rafter’ laminated insulation board, between timber rafters in tiled or slated pitched roofs.

This composite system of insulation provides all the benefits of reduced U-values, controlled air leakage and air infiltration and reduces thermal bridging to a minimum.


WALLTITE® has undergone various performance tests. Certificates are available on request.

LABC RegisteredNBS Plus

Typical detail

New roof with board insulation

New roof with board insulation

  1. WALLTITE® CL100 insulation between rafters to achieve target U-value
  2. Over rafter PIR board insulation (minimum 50mm thick)
  3. Breathable roof tile underlay
  4. Counter-batten
  5. Unventilated air space
  6. Plasterboard and skim

Habitable space: plasterboard and skim/VCL with taped joints VCL to be carefully cut and sealed around struts, ceiling joists and penetrations); batten/counter batten rafters as necessary to achieve insulation depth, confirm rafter strength sufficient to receive counter battening and boarding if required.

Loft space only, non habitable: insulated between and over rafters to achieve target U-value. WALLTITE® may remain exposed.

Technical data

Specification Spray applied polyurethane foam between rafters, directly onto board insulation
NBS clause P10 15A
Air leakage (50mm) 0.0033m3hrm2
Lambda 90/90 0.025 - 0.028W/mK
Fire rating Class 1 to BS 476: Part 7
Water vapour diffusion resistance factor 61.12


Thickness of WALLTITE (mm) Thichness of board (mm) U-value (W/m2k)
90 50 0.18
90 100 0.13

Additional resources