Limiting Height of Chimneys and Parapet walls
Proportion for Masonry Chimneys
Limiting Height of Chimneys
Where a chimney is not adequately supported by ties or securely restrained in any way, its height H when 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 1500 kg/m? (ie brickwork, heavyweight concrete block etc.), where:
W = the least horizontal dimension of the chimney measured at the same point of intersection, and
H = measured to the top of any chimney pot or other flue terminal.
Limiting Height of Parapet walls
The minimum thickness and maximum height of parapet walls should be as indicated in the diagram below.
If the criteria indicated below cannot be attained design calculations should becarried out to indicate suitability.
 |
Thickness
(mm) |
Parapet height H
to be not more than
(mm) |
t1 + t2
equal or less than 200 |
600 |
t1 + t2
greater than 200
equal to or less than 250 |
860 |
|
 |
Thickness
(mm) |
Parapet height H
to be not more than
(mm) |
| t = 150 |
600 |
| t = 190 |
760 |
| t = 215 |
860 |
|
| Note: t should be less than or equal to T |
Note, the above guidance relates only to structural aspects of parapet wall design. Further advice should be obtained
with regard to moisture penetration.
Please check with your local building control department before using information contained in this page to ensure that they comply with your local building codes. |
