Difference between revisions of "Effective Roof Area, (A)"
(2 intermediate revisions by the same user not shown) | |||
Line 18: | Line 18: | ||
== With Wind driven rain == | == With Wind driven rain == | ||
− | |||
Where allowance is made for wind, the effective roof area shall be calculated as follows; | Where allowance is made for wind, the effective roof area shall be calculated as follows; | ||
Line 33: | Line 32: | ||
|<math>A = L_R \sdot T_R</math> | |<math>A = L_R \sdot T_R</math> | ||
|- | |- | ||
− | |colspan="2"|'''NOTES:''' | + | |colspan="2"|'''NOTES:'''<br /><math>L_R</math> is the length of roof to be drained, in metres <math>(m)</math>;<br /><math>B_R</math> is the plan width of roof from gutter to ridge, in metre <math>(m)</math>;<br /><math>H_R</math> is the height of roof from gutter to ridge, in metres <math>(m)</math>;<br /><math>T_R</math> is the distance from gutter to ridge measured along the roof, in metres <math>(m)</math><br /><math>A</math> is the effective impermeable roof area, in square metres <math>(m^2)</math>. |
− | + | ||
− | + | In areas where wind is taken into account in rainfall calculations, where rain driven against a wall by the wind can run down onto the roof or into a gutter, 50% of the area of the wall shall be added to the effective area of the roof. | |
− | <br /><math>B_R</math> is the plan width of roof from gutter to ridge, in metre (m); | + | |
+ | [[File:Roof dimension.jpeg]] | ||
+ | |||
+ | |||
+ | == References == | ||
+ | #BS EN 12056-3:2000 Gravity drainage systems inside buildings |
Latest revision as of 15:43, 25 May 2017
- According to BS EN 12056-3, it is the surface area of roof where in with/ without wind driven rain is considered.
Without Wind driven rain
Where no allowance is made for wind, the Effective Roof Area (A) shall be calculated from the equation;
where;
is the effective roof area, in square metres ;
is the length of roof to be drained, in metres ;
is the width of roof from gutter to ridge, in metres .
With Wind driven rain
Where allowance is made for wind, the effective roof area shall be calculated as follows;
Effective impermeable roof area | |||||
---|---|---|---|---|---|
Allowance to be made for the effect of wind | Effective impermeable roof area, | ||||
Wind driven rain, 26° to vertical | |||||
Rain perpendicular to roof (i.e. surface area of roof used) | |||||
NOTES: is the length of roof to be drained, in metres ; is the plan width of roof from gutter to ridge, in metre ; is the height of roof from gutter to ridge, in metres ; is the distance from gutter to ridge measured along the roof, in metres is the effective impermeable roof area, in square metres . In areas where wind is taken into account in rainfall calculations, where rain driven against a wall by the wind can run down onto the roof or into a gutter, 50% of the area of the wall shall be added to the effective area of the roof. Error creating thumbnail: Unable to save thumbnail to destination
References
|