BS 7456:1991

Committees responsible
Foreword
Code of practice
0. Introduction
1. Scope
2. Definitions
3. Suitability of cavity walls
4. Polyurethane foam system
5. Thermal performance of installed polyurethane
     foam
6. Pre-installation preparation of the building
7. Filling process
8. Installation of the polyurethane foam system
9. Post-installation activities
10. Declaration
11. Records
Appendices
A. Criteria of suitability of external cavity walls
B. Fire performance of polyurethane foam when
     installed in a wall cavity
C. Notes for designers
D. Flue checks for appliances of rated input not
     exceeding 60 kW
E. Methods for determining cavity width
Figures
1. Staggered drilling pattern (representing maximum
     spacing)
2. Elevations of semi-detached property: unit area
     plan for injection
3. Overall pattern of filling for a nominal 50 mm
     wide cavity
4. Measurement of cavity width
5. Estimation of cavity width

Optimum procedure for insulating masonry cavity walls.

This British Standard gives recommendations for the installation of rigid polyurethane (PUR) foam systems complying with BS 7457:1994, which are dispensed on site, to fill cavities of maximum width 150 mm of suitably constructed external walls of maximum continuous cavity height 12 m which have masonry or concrete inner and outer leaves, thereby providing additional thermal insulation to such walls and simultaneously, especially in the case of walls with damaged wall ties, improving their structural integrity.

It defines what are suitably constructed external walls and indicates essential procedures and precautions necessary to optimise the filling process. Walls built of random rubble are not covered by this code.

NOTE The titles of the publications referred to in this standard are listed on the inside back cover.