Smoking shelter distance
The picture above shows a structure, which is marketed as a smoking shelter. It has a height of 2.2m, length 2.2m and depth of 1.3m. It has a side, a part side and back which contain a gap of 0.3.m at the base of each. It is distanced approximately 0.3 m from a building wall.
If we assume the perimeter to be under the roof then:
Total area on perimeter (T) = 2(2.2 x 2.2) + 2(1.3 x 2.2) = 9.68 + 5.72 = 15.4m2
Total area of solids (X) = (0.4 x 1.9) + (1.9 x 2.2) + (1.9 x 1.3) = 7.41m2
Totals area of gaps (space) (Y) = T- X = 15.4 - 7.41 = 7.99m2.
Expressed as %, X (solid) is 48.1 % of the smoking structure and Y (space) is 51.9%, so Y is at least 50% of the structure. The structure complies, is not substantially enclosed, and smoking could be allowed.
In South Ayrshire we would be concerned that the structure is placed near a building wall. We would contend that the building wall is sheltering and therefore the building wall should be considered as being part of the structure and that the building wall is in fact serving the purpose of a wall for the structure.
We would say that the perimeter for calculation should not be set by the roof but should be extended to include the building wall and the distance from the wall.
T = 2(2.2 x 2.2) + 2(1.6 x 2.2) = 16.72m2
X = 7.41 + (2.2 x 2.2) = 12.25m2
Y = T - X = 4.47 m2
Expressed as %, X (solid) is 73.4% of the smoking structure and Y (space) is 26.7%, so Y is not at least 50% of the structure. It would be our view that the shelter as sited does not comply, is substantially enclosed, and smoking should not be allowed.
In South Ayrshire we have taken a pragmatic and practical view at to how far a smoking structure can be sited from another structure such as a building wall . As a guide to we set that distance at 1.5 metres.
In the worked example if we were to site the shelter 1.5 m from the building wall then T = 22 m2, X = 12.25m2 and Y = 9.75 m2. Mathematically Y is 44.3% of the structure and is not at least 50%, so mathematically the structure is substantially enclosed. The shelter would have to be sited just over 2m away from the building wall to obtain at least 50%.
However we are dealing with real situations and not mathematical theory. The sheltering effect caused by the building wall on the shelter will have many variables and cannot be readily calculated. Variables include: What significance does the building corner make? What is the prevailing wind direction? The building wall is constructed of brick (rough surface) and cladding (smooth surface), each will have different effects?
The numerous variables and the fact that each situation is unique means that in practical terms the sheltering effect cannot be calculated. However, the sheltering effect exists and hence is the reason why in South Ayrshire we set a guide distance of 1.5m.
Why 1.5m? The distance is simply a guide value and each situation should be looked at on its own merits. We would always advocate trying to get as much distance as possible between a smoking structure and another structure to assist in air circulation. However in situations such as small enclosed court yards this is not always possible, therefore the 1.5m becomes our minimum requirement and should be achievable in all situations.
So for instance had the shelter in the worked example not been on a corner of the building but further along we may have tried to persuade the owner to site the structure at a greater distance than 1.5m, perhaps to nearer to the 2m or more indicated by the mathematical calculation.
As stated it is our view that 1.5m should be achievable in all situations. If not then we are likely to form the view that the area may be too small to be used for a smoking structure. However we would not reject any proposal before fully assessing the situation and may be able to offer practical advice.