Spray Foam Insulation

Existing pitched roof insulation

WALLTITE® can be applied directly onto the underside of existing slate or tiled roofs. It seals any air gaps, preventing the ingress of windblown snow, rain, dust and unwanted air infiltration.

The water vapour permeability of WALLTITE® permits all roof timbers to dry out following periods of solar radiation.

WALLTITE® is applied between rafters in sloping ceiling areas and loft conversions. Plasterboard can then be fixed to the rafters.

In applications such as barn conversions the foam is dubbed out with a coat of bonding plaster and then finish plaster. Existing structures must be in a good state of repair with no evidence of rain penetration or damp. Defects should be made good prior to installing the product. WALLTITE® also reduces airborne noise pollution from air and road traffic.


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

LABC RegisteredNBS Plus

Typical detail

Existing roof with breathable underlay

Existing roof with breathable underlay

  1. WALLTITE® CL100 insulation to achieve target U-value
  2. Plasterboard and skim (optional)
  3. Unventilated air space
  4. WALLTITE® returned to insulated cavity stop at head of wall
  5. Non-combustible cavity stop, well bedded and sealed

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 in a non-habitable loft space.

Repair all roof defects and thoroughly overhaul where necessary prior to spraying.

Technical data

Specification Spray applied polyurethane foam between battens and rafters, directly onto existing tiles or slates
NBS clause P10 15A
Air leakage (50mm) 0.0033m3hrm2
Lambda 90/90 0.025W/mK
Fire rating Class 1 to BS 476: Part 7
Water vapour diffusion resistance factor 61.12
Adhesion to tiles 123kPa


Thickness of WALLTITE (mm) U-value (W/m2k)
190 0.14
160 0.16
140 0.18

Additional resources

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