|
BS 5534:2003 Code of Practice for slating and tiling (including
shingles)
BS 6399-2: 1997 Loadings for Buildings Part 2. Code of practice for wind loads |
| Basic Wind Speed |
| The standard gives basic wind speeds for locations in the UK, the
speeds are hourly mean wind speeds likely to be exceeded on average
only once in 50 years |
| As an aid we have chosen a selection of towns throughout the UK,
and determined the the basic wind speed. |
| If there is a town or towns that you would like to be included
please let us know |
| Altitude Factor |
| The altitude factor Sa is used to adjust the basic wind speed for
the altitude of the site above sea level. In preparation of the
tables it has been assumed that there is no significant topography.
|
| As a generalisation any building more than half-way up a hill, or
an on a ridge or cliff will have increase wind loading. If your
project falls into this category, then please contact us for a more
detailed analysis. |
In the preparation of the table 4 categories of height above sea
level have been used
- 0-50m
- 51-100m
- 101-150m
- 151-200m
|
| Direction Factor |
| The
direction factor Sd has been taken as 1, which is suitable for buildings
where the orientation is unknown or ignored. Where a more detailed
analysis is required, please contact us. |
| Seasonal Factor |
| The
seasonal factor Ss has been taken as 1, which is suitable for permanent
buildings |
| Probability Factor |
| The
probability factor Sp is taken as 1, which is equivalent to a return
period of 50 years |
| Site Exposure |
| Two categories of ground roughness have been considered
|
| The town category is defined as built-up areas with an average
level of roof above ground level of at least 5m. |
| For a building to be considered as town, then the building must be
at least 2km inside the town terrain. |
| The distance from the sea is required, for simplicity
4 categories
have been use in the preparation of the tables
|
| For buildings within 2km of the sea or estuary, a more detailed
analysis will be required. |
| Building Height |
| The building height should be taken as the maximum height of the
building above ground level. |
| The effective height (as defined in the standard) is taken as the
actual building height. |
| Pressure Coefficients |
The following
coefficients have been used in the
preparation of the tables
External
Pressure difference coefficient (Cpt)
Uplift pressure reduction factor (R) |
Note
For simplicity only the local area coefficients have been considered. |
Monopitch Roofs
| Pitch |
R |
Cpt |
| 35 |
0.13 |
-0.21 |
| 40 |
0.13 |
-0.21 |
| 45 |
0.14 |
-0.21 |
| 50 |
0.15 |
-0.21 |
| 55 |
0.16 |
-0.21 |
| 60 |
0.18 |
-0.21 |
|
Duopitch Roofs
| Pitch |
R |
Cpt |
| 35 |
0.12 |
-0.13 |
| 40 |
0.12 |
-0.13 |
| 45 |
0.12 |
-0.13 |
| 50 |
0.12 |
-0.13 |
| 55 |
0.11 |
-0.13 |
| 60 |
0.11 |
-0.13 |
|
| Internal
(Cpi) |
| +0.2 |
| Plain
Tile Properties |
| Cover
width |
B |
165 |
mm |
| Gauge |
Ga |
100 |
mm |
| Air
permeability |
D |
2.7 |
|
| Substrate
shielding factor |
S |
1 |
|
| Self
weight of tile |
|
1 |
kg |
| Tile
pitch |
|
10 |
degrees |
| Nib
to centre of exposed surface |
Lf |
200 |
mm |
| Nib
to centre of gravity |
Lw |
118 |
mm |
| Nib
to nail hole |
Ln |
15 |
mm |
| Hanging
length |
Lh |
250 |
mm |
|
