Section 2D Proportions for masonry chimneys above the roof surface

Proportions for masonry chimneys above the roof surface

  1. Height to width relationship

    Height to width relationship

    2D1. Where a chimney is not adequately supported by ties or securely restrained in any way, its height if measured from the highest point of intersection with the roof surface, gutter, etc. should not exceed 4.5W, provided the density of the masonry is greater than 1500kg/m3, where:

    • W is the least horizontal dimension of the chimney measured at the same point of intersection, and
    • H is measured to the top of any chimney pot or other flue terminal (see Diagram 20).
    **** Image Diagram 20 Proportions for masonry chimneys  

    • 1 Size and proportion of residential buildings of not more than three storeys Diagram 1 Size and proportion of residential buildings of not more than three storeys
    • 2 Size and proportion of non-residential buildings and annexes Diagram 2 Size and proportion of non-residential buildings and annexes
    • 3 Determination of wall thickness Diagram 3 Determination of wall thickness
    • 4 Parapet walls - height Diagram 4 Parapet walls - height
    • 5 Maximum floor area enclosed by structural walls Diagram 5 Maximum floor area enclosed by structural walls
    • 6 Fig 1-2 - Map showing wind speeds in m per s for maximum height of buildings Diagram 6 Fig 1-2 - Map showing wind speeds in m per s for maximum height of buildings
    • 6 Fig 3 - Map showing wind speeds in m per s for maximum height of buildings Diagram 6 Fig 3 - Map showing wind speeds in m per s for maximum height of buildings
    • 7 Max height of buildings Diagram 7 Max height of buildings
    • 8 Measuring storey and wall heights Diagram 8 Measuring storey and wall heights
    • 9 Declared compressive strenght of masonry units Diagram 9 Declared compressive strength of masonry units
    • 10 Maximum span of floors Diagram 10 Maximum span of floors
    • 11 Differences in ground levels Diagram 11 Differences in ground levels
    • 12 Openings in a buttressing wall Diagram 12 Openings in a buttressing wall
    • 13 Buttressing Diagram 13 Buttressing
    • 14 Sizes of openings and recesses Diagram 14 Sizes of openings and recesses
    • 15 Lateral support by floors Diagram 15 Lateral support by floors
    • 16 Lateral support at roof level Diagram 16 Lateral support at roof level
    • 17 Size and location of openings Diagram 17 Size and location of openings
    • 18 Wall thinckness Diagram 18 Wall thinckness
    • 19 Lateral restraint at roof level Diagram 19 Lateral restraint at roof level
    • 20 Proportions for masonty chimneys Diagram 20 Proportions for masonry chimneys
    • 21 Elevation of stepped foundation Diagram 21 Elevation of stepped foundation
    • 22 Piers and chimneys Diagram 22 Piers and chimneys
    • 23 Foundation dimensions Diagram 23 Foundation dimensions
    • 24 Area at risk of collapse in the event of an accident Diagram 24 Area at risk of collapse in the event of an accident
    • Table 1 Areas at risk from house longhorn beetle Table 1 Areas at risk from house longhorn beetle
    • Table 2 Wall types considered in this section Table 2 Wall types considered in this section
    • Table 3 Minimum thickness of certain external walls, compartment Table 3 Minimum thickness of certain external walls, compartment
    • Table 4 Imposed loads Table 4 Imposed loads
    • Table 5 Cavity wall ties Table 5 Cavity wall ties
    • Table 6 Declared compressive strength of masonry units complying with BS EN 771-1 TO -5 [N PER nn SQ] Table 6 Declared compressive strength of masonry units complying with BS EN 771-1 TO -5 (N/mm SQ)
    • Table 7 Normalised compressive strength of masonry units of clay and calcium silicate blocks complying with BS EN 771-1 and 2 [Nn/mm SQ] Table 7 Normalised compressive strength of masonry units of clay and calcium silicate blocks complying with BS EN 771-1 and 2 (N/mm SQ)
    • Table 8 Value of Factor X - see Dia 14 Table 8 Value of Factor 'X' (see Dia 14)
    • Table 9 Lateral support for walls Table 9 Lateral support for walls
    • Table 10 Minimum width of strip footings Table 10 Minimum width of strip footings
    • Table 11 Building consequence Table 11 Building consequence