Annex A: Method for calculating mass per unit area

A1 Wall mass A1.1 Where a mass is specified it is expressed as mass per unit area in kilograms per square metre (kg/m²). A1.2 The mass may be obtained from the manufacturer or it may be calculated by the method given in this annex. To calculate the mass per unit area of a masonry leaf use the formula below. This formula is not exact but is sufficient for this purpose. A2 Formula for calculation of wall leaf mass per unit area A2.1   Mass per unit area of a brick/block leaf = mass of co-ordinating area / co-ordinating area Equation A2.1 Equation A2.1 Note: This formula provides the mass per unit area of the block/brick construction without surface finish. Note: See Diagram A.1 for block and mortar dimensions. A2.2 When calculating the mass per unit area for bricks and blocks use the density at the appropriate moisture content from Table 3.2, CIBSE Guide A (1999). A2.3 For cavity walls the mass per unit area of each leaf is calculated and added together. A2.4 Where surface finishes are used the mass per unit area of the finish is added to the mass per unit area of the wall. A1 Block and mortar dimensions A1 Block and mortar dimensions A3 Simplified equations A3.1 Two examples are given (see Table A.1 and A.2) using the equation in A2.1. For each of these examples a simplified equation is obtained for that type of construction. Table A1 Blocks laid flat Table A1 Blocks laid flat Table A2 Blocks laid on edge Table A2 Blocks laid on edge A4 Mass per unit area of surface finishes A4.1 The mass per unit area of surface finishes should be obtained from manufacturer’s data. A5 Mass per unit area of floors A5.1 The mass of a solid and homogeneous floor (without hollows, beams or ribs) can be calculated from: Equation A5.1 Equation A5.1 A5.2 The mass of a beam and block floor can be calculated from: Equation A5.2 Equation A5.2 Note: See Diagram A.2 for beam and block floor dimensions. A2 Beam and block floor dimensions A2 Beam and block floor dimensions A5.3 For other floor types (including floors with variable thickness), seek advice from the manufacturer on mass per unit area and performance.

  • 0.1 Requirement E1 0.1 Requirement E1
  • 0.2 Requirement E2(a) 0.2 Requirement E2(a)
  • 0.3 Requirement E2(b) 0.3 Requirement E2(b)
  • 2.1 Types of separating wall 2.1 Types of separating wall
  • 2.2 Wall type 1.1 2.2 Wall type 1.1
  • 2.3 Wall type 1.2 2.3 Wall type 1.2
  • 2.4 Wall type 1.3 2.4 Wall type 1.3
  • 2.5 Wall type 1 - external cavity wall with masonry inner leaf 2.5 Wall type 1 - external cavity wall with masonry inner leaf
  • 2.6 Wall type 1 - bonded junction - masonry inner leaf of external cavity wall with solid separating wall 2.6 Wall type 1 - bonded junction - masonry inner leaf of external cavity wall with solid separating wall
  • 2.7 Wall type 1 - tied junction - external cavity wall with internal masonry wall 2.7 Wall type 1 - tied junction - external cavity wall with internal masonry wall
  • 2.8 Wall type 1 - position of openings in masonry inner leaf of external cavity wall 2.8 Wall type 1 - position of openings in masonry inner leaf of external cavity wall
  • 2.9 Wall type 1 - external cavity wall with timber frame inner leaf 2.9 Wall type 1 - external cavity wall with timber frame inner leaf
  • 2.10 Wall type 1 - internal timber floor 2.10 Wall type 1 - internal timber floor
  • 2.11 Wall type 1 - internal concrete floor 2.11 Wall type 1 - internal concrete floor
  • 2.12 Wall type 1 - concrete ground floor 2.12 Wall type 1 - concrete ground floor
  • 2.13 Wall type 1 - ceiling and roof junction 2.13 Wall type 1 - ceiling and roof junction
  • 2.14 External cavity wall at eaves level 2.14 External cavity wall at eaves level
  • 2.15 Wall type 2.1 2.15 Wall type 2.1
  • 2.16 Wall type 2.2 2.16 Wall type 2.2
  • 2.17 Wall type 2.3 2.17 Wall type 2.3
  • 2.18 Wall type 2.4 2.18 Wall type 2.4
  • 2.19 Wall types 2.1 and 2.2 - external cavity wall with masonry inner leaf 2.19 Wall types 2.1 and 2.2 - external cavity wall with masonry inner leaf
  • 2.20 Wall types 2.3 and 2.4 - external cavity wall with masonry inner leaf - stagger 2.20 Wall types 2.3 and 2.4 - external cavity wall with masonry inner leaf - stagger
  • 2.21 Wall type 2 - tied junction - external cavity wall with internal masonry wall 2.21 Wall type 2 - tied junction - external cavity wall with internal masonry wall
  • 2.22 Wall type 2 - external cavity wall with timber frame inner leaf 2.22 Wall type 2 - external cavity wall with timber frame inner leaf
  • 2.23 Wall type 2 - internal timber floor 2.23 Wall type 2 - internal timber floor
  • 2.24 Wall type 2 - internal concrete floor and concrete ground floor 2.24 Wall type 2 - internal concrete floor and concrete ground floor
  • 2.25 Wall type 2 - ceiling and roof junction 2.25 Wall type 2 - ceiling and roof junction
  • 2.26 External cavity wall at eaves level 2.26 External cavity wall at eaves level
  • 2.27 Wall type 3.1 with independent composite panels 2.27 Wall type 3.1 with independent composite panels
  • 2.28 Wall type 3.1 with independent plasterboard panels 2.28 Wall type 3.1 with independent plasterboard panels
  • 2.29 Wall type 3.2 with independent composite panels 2.29 Wall type 3.2 with independent composite panels
  • 2.30 Wall type 3.3 with independent composite panels 2.30 Wall type 3.3 with independent composite panels
  • 2.31 Wall type 3 - external cavity wall with masonry inner leaf 2.31 Wall type 3 - external cavity wall with masonry inner leaf
  • 2.32 Wall type 3 - external cavity wall with internal timber wall 2.32 Wall type 3 - external cavity wall with internal timber wall
  • 2.33 Wall type 3 - internal timber floor 2.33 Wall type 3 - internal timber floor
  • 2.34 Wall types 3.1 and 3.2 - internal concrete floor 2.34 Wall types 3.1 and 3.2 - internal concrete floor
  • 2.35 Wall types 3.1 and 3.2 - ceiling and roof junction 2.35 Wall types 3.1 and 3.2 - ceiling and roof junction
  • 2.36 External cavity wall at eaves level 2.36 External cavity wall at eaves level
  • 2.37 Wall type 4.1 2.37 Wall type 4.1
  • 2.38 Wall type 4 - external cavity wall with timber frame inner leaf 2.38 Wall type 4 - external cavity wall with timber frame inner leaf
  • 3.1 Types of separating floor 3.1 Types of separating floor
  • 3.2 Ceiling treatments A, B and C 3.2 Ceiling treatments A, B and C
  • 3.3 Floor type 1.1C - floor type 1.1 with ceiling treatment C 3.3 Floor type 1.1C - floor type 1.1 with ceiling treatment C
  • 3.4 Floor type 1.2B - floor type 1.2 with ceiling treatment B 3.4 Floor type 1.2B - floor type 1.2 with ceiling treatment B
  • 3.5 Floor type 1.2B - external cavity wall with masonry inner leaf 3.5 Floor type 1.2B - external cavity wall with masonry inner leaf
  • 3.6 Floor type 1 - floor penetrations 3.6 Floor type 1 - floor penetrations
  • 3.7 Floor type 1.1C - wall type 1 3.7 Floor type 1.1C - wall type 1
  • 3.8 Floor type 1.2B - wall type 1 3.8 Floor type 1.2B - wall type 1
  • 3.9 Floor type 1.1C and 1.2B - wall type 2 3.9 Floor types 1.1C and 1.2B - wall type 2
  • 3.10 Floor type 1.1C - wall type 3.1 and 3.2 3.10 Floor type 1.1C - wall types 3.1 and 3.2
  • 3.11 Floating floors (a) and (b) 3.11 Floating floors (a) and (b)
  • 3.12 Floor type 2.1C(a) - floor type 2.1 with ceiling treatment C and floating floor (a) 3.12 Floor type 2.1C(a) - floor type 2.1 with ceiling treatment C and floating floor (a)
  • 3.13 Floor type 2.1C(b) - floor type 2.1 with ceiling treatment C and floating floor (b) 3.13 Floor type 2.1C(b) - floor type 2.1 with ceiling treatment C and floating floor (b)
  • 3.14 Floor type 2.2B(a) - floor type 2.2 with ceiling treatment B and floating floor (a) 3.14 Floor type 2.2B(a) - floor type 2.2 with ceiling treatment B and floating floor (a)
  • 3.15 Floor type 2.2B(b) - floor type 2.2 with ceiling treatment B and floating floor (b) 3.15 Floor type 2.2B(b) - floor type 2.2 with ceiling treatment B and floating floor (b)
  • 3.16 Floor type 2 - external cavity wall with masonry internal leaf 3.16 Floor type 2 - external cavity wall with masonry internal leaf
  • 3.17 Floor type 2 - floor penetrations 3.17 Floor type 2 - floor penetrations
  • 3.18 Floor types 2.2B(a) and 2.2B(b) - wall type 1 3.18 Floor types 2.2B(a) and 2.2B(b) - wall type 1
  • 3.19 Floor types 2.1C - wall types 3.1 and 3.2 3.19 Floor types 2.1C - wall types 3.1 and 3.2
  • 3.20 Floor type 3.1A 3.20 Floor type 3.1A
  • 3.21 Floor type 3 - floor penetrations 3.21 Floor type 3 - floor penetrations  
  • 3.22 Floor type 3 - wall type 1 3.22 Floor type 3 - wall type 1
  • 3.23 Floor type 3 - wall type 2 3.23 Floor type 3 - wall type 2
  • 4.1 Treatments for material change of use 4.1 Treatments for material change of use
  • 4.2 Wall treatment 1 4.2 Wall treatment 1
  • 4.3 Floor treatment 1 4.3 Floor treatment 1
  • 4.4 Floor treatment 1 - high window head detail 4.4 Floor treatment 1 - high window head detail
  • 4.5 Floor treatment 1 - wall treatment 1 4.5 Floor treatment 1 - wall treatment 1
  • 4.6 Floor treatment 2 4.6 Floor treatment 2
  • 4.7 Floor treatment 2 - wall treatment 1 4.7 Floor treatment 2 - wall treatment 1
  • 4.8 Stair treatment 4.8 Stair treatment
  • 4.9 Floor penetrations 4.9 Floor penetrations
  • 5.1 Internal wall type A 5.1 Internal wall type A
  • 5.2 Internal wall type B 5.2 Internal wall type B
  • 5.3 Internal wall type C 5.3 Internal wall type C
  • 5.4 Internal wall type D 5.4 Internal wall type D
  • 5.5 Internal floor type A 5.5 Internal floor type A
  • 5.6 Internal floor type B 5.6 Internal floor type B
  • 5.7 Internal floor type C 5.7 Internal floor type C
  • 6.1 Ceiling void and roof space 6.1 Ceiling void and roof space
  • A1 Block and mortar dimensions A1 Block and mortar dimensions
  • A2 Beam and block floor dimensions A2 Beam and block floor dimensions
  • Table 0.1a Dwelling-houses and flats - performance standards for separating walls, separating floors, and stairs that have a separating function Table 0.1a Dwelling-houses and flats - performance standards for separating walls, separating floors, and stairs that have a separating function
  • Table 0.1b Rooms for residential purposes - performance standards for separating walls, separating floors, and stairs that have a separating function Table 0.1b Rooms for residential purposes - performance standards for separating walls, separating floors, and stairs that have a separating function
  • Table 0.2 Laboratory values for new internal walls and floors within dwelling-houses, flats and rooms for residential purposes, whether purpose built or formed by material change of use Table 0.2 Laboratory values for new internal walls and floors within dwelling-houses, flats and rooms for residential purposes, whether purpose built or formed by material change of use
  • Table 2.1 Separating wall junctions reference table Table 2.1 Separating wall junctions reference table
  • Table 3.1 Separating floor junctions reference table Table 3.1 Separating floor junctions reference table
  • Table 7.1 Absorption coefficient data for common materials in buildings Table 7.1 Absorption coefficient data for common materials in buildings
  • Table 7.2 Example calculation for an entrance hall (Method B) Table 7.2 Example calculation for an entrance hall (Method B)
  • Table A1 Blocks laid flat Table A1 Blocks laid flat
  • Table A2 Blocks laid on edge Table A2 Blocks laid on edge