To design a sloped or flat roof drainage system we need to know several things.
Sloped roof drainage design residential.
The maximum rainfall rate anticipated in the area where the building is located the flow in liters per minute per square meter for some x number of minutes.
At page top and at left our photos show a low slope roof surrounded by a parapet.
There are three types of drain systems commonly used on flat roofs.
This form of roof drainage is preferred if a clean exterior appearance is desired.
First there is drainage.
Sloped roofs on this modern house match the rest of the lines used on the exterior to create a futuristic looking home.
Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally.
The drainage requirements for flat roofs on buildings present some special problems that we describe and illustrate here.
Each of these systems has its own pros and cons.
You will need to determine the drainage area or the area of impervious surface that drains to each practice.
Water could then pour off overhanging roof eaves onto the ground below or in more sophisti cated assemblies flow toward the perimeter and into a clay wood or metal gutter system or through a drainage outlet in the exterior walls.
Historically roof drainage was ac complished by simply sloping the roof downward.
Healthy drainage occurs when the slope is between 2 percent and 5 percent which equates to 2 to 5 inches of drop off for every 10 feet you measure as you move away from your home.
This data is available in excruciating detail for most countries in weather map form and as you ll read.
Watch for clogs blockage at the roof drain or scupper.
A sloped roof all on it s own okay with help from gravity is going to take those nasty weather elements and move them down to the ground.
For example if a practice will receive runoff from a single downspout that drains of a rooftop you would calculate the drainage area by dividing the entire roof area by 4 see figure 1.
Lucid architecturedesigned this house in western michigan.
The sloped roofs on this wood clad modern home promote excellent drainage and open up the house to allow to take advantage of the greenery around it.
The roof is sloped towards the drain through either tapered insulation or through joist modifications.
At first glance that s a good thing but not so much when you realize that it would be poor design to have all sides of a roof pouring water on you.
To size the vertical roof drain for the same parameters 5 000 square feet of room area and 6 per hour of rain consult table 1106 2 figure 3.
These will drain to somewhere near the center of the roof and down through the building to underground storm mains or a detention pond.
