storm drainage

8/8/2019 Storm Drainage

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Storm DrainageStorm DrainageA step by step approachA step by step approach


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Determine Location RainfallDetermine Location Rainfall

Where is your building find the rainfall

data for your building location in the

National Building Code

the rainfall intensity is given under the

column:

15 min. rain mm


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Determine roof areaDetermine roof area

Use the roof area directly for flat roofs

if there is a wall that drains onto the roof add

half of the largest wall area to this roof area

lower roof

area

of wall area adds to

lower roof area


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Other rulesOther rules if the roof area is greater than900 m2 or the roof is bigger than

30m in any one direction then

you need a second roof drain

Best practice is to

use minimum two

drains per roof

40 m

25m


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Layout Roof DrainsLayout Roof Drains

Locate the roof drains in the middle of

imaginary panels


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Decide on piping layoutDecide on piping layout

Straight leaders

interferes with space

good drainage with little chance

of overflow

Offset leaders

Flexible layout

Add cleanouts for 90 degreebends

straight

leader

offset

leader

CO

Roof drain

(RD)

RD

cleanout

(CO)

CO


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Lay out drainage pipingLay out drainage piping

Plan view showing roof drains, building

drain and building outline

CO


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Riser view showing cleanouts and building

storm drain

Roof

drain

(RD)

RD

RD

leader

building

storm drain building

storm sewer

1:100 TYPICAL

CO CO CO CO


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Slope of building storm drain and invert

notes.

1:100 TYPICAL

CO CO CO CO

below frost

line

Invert Elev

43.000

Invert Elev

42.840

16.0 m


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Summary of rulesSummary of rules

cleanout at the bottom of all rain water

leaders

insulate rainwater pipes with waterproof

insulation to prevent condensation

maximum 900m2 per roof drain

max 15 m to edge and 30 m betweendrains


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min two drains per roof for best practice

add area of largest adjacent wall to roof

area show invert elevation at building storm

sewer and at farthest end of building

drain(s)

Summary of rulesSummary of rules contdcontd


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Assignment Due FridayAssignment Due Friday

- Include spec sheet- Include spec sheet

storm drainage

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