wavin OSMA Rainwater - Page 7

Design Procedures
Wavin Osma Rainwater
www.wavin.co.uk 49
A
B
B
A
C
Figure1:Pitchedroof
Table1:MaximumE�ectiveRoofArea(m)
Running outlet at END of gutter
Running outlet at CENTRE of gutter
Stopend outlet at END of gutter
System
Gutter laid
level
Gutter laid
at fall 1:600
Gutter laid
level
Gutter laid
at fall 1:600
Gutter laid
level
Gutter laid
at fall 1:600
RoundLine 63 79 126 163 60 60
SquareLine 67 96 149 178 63 63
StormLine■ 117 130 228 254 63 63
StormLinel 115 125 221 239 61 61
DeepLine 114 145 228 299 – –
SuperLine 101 121 207 250 – –
RoofLine 119 164 245 317 – –
NOTE:TheroofareascapableofbeingdrainedarecalculatedinaccordancewithBSEN12056:Part3:2000,towhichreferenceshouldbemadebeforevaryingdesignconsiderations.
Calculating Effective Roof Area:
Pitched Roof
TherearetwomethodsofcalculatingE�ectiveRoofArea,
whichallowsforthee�ectsofwind.
Method 1(seeFigure1)
BSEN12056:Part3:2000
1. Measureinmetres:
A.Lengthfromeavestoridge
B. Heightofrooffromeavestoridge
C. Lengthofroof
2. UsetheformulaspeciedinBSEN12056:Part3:2000
E�ectiveRoofArea(inm)=(A+B)xC
  ––
2
3. CheckthisgureagainstthecapacityofWavinOsma
systemssetoutinTable1.
Workedexample:
A=7.0m  (7+1.5)x12
B=3.0m  8.5x12=102m
C=12.0m E�ectiveRoofArea
Conclusion:inthisexample,Table1showsthat:
• IfrunningoutletpositionedatENDofrun:StormLine,
DeepLineandRoofLinearesuitableiflaidlevel.All
systems(exceptRoundLineandSquareLine)are
suitablelaidtoafallof1:6000
• IfoutletpositionedatCENTREofrun:Allsystemsare
suitableiflaidlevelortoafallof1:600.
Method 2(seeFigure1)
BuildingRegulationsPartH1990
1. Measureroofplanareainsquaremetres:Length(L)x
Width(W)=Area(m)
2. TondE�ectiveRoofArea,multiplyroofplanareaas
follows,accordingtoangleofpitch:
• if30ºpitch–Areax1.29
• if45ºpitch–Areax1.5
• if60ºpitch–Areax1.87
Determining Gutter Flow Capacity
Thecapacityofarainwatersystemtoe�ectivelydrainaroofareadependsonfourfactors:GuttercapacityLeveltowhich
thegutterislaidNumberofoutletsLocationofoutletsTodeterminethecorrectcombination,rstcalculatetheareato
bedrained–theE�ectiveRoofArea.
7+3x12
 ––
2