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