Lucid architecturedesigned this house in western michigan.
Sloped roof drainage design residential.
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.
At page top and at left our photos show a low slope roof surrounded by a parapet.
Watch for clogs blockage at the roof drain or scupper.
Historically roof drainage was ac complished by simply sloping the roof downward.
You will need to determine the drainage area or the area of impervious surface that drains to each practice.
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.
According to the chart for 1 8 slope per 12 of pipe for 5 000 square feet of roof area with a 6 per hour of rainfall the required pipe size is 8.
Sloped roofs on this modern house match the rest of the lines used on the exterior to create a futuristic looking home.
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.
Each of these systems has its own pros and cons.
To design a sloped or flat roof drainage system we need to know several things.
Roofs of this design will have one or more roof drains or scuppers installed.
This data is available in excruciating detail for most countries in weather map form and as you ll read.
First there is drainage.
The drainage requirements for flat roofs on buildings present some special problems that we describe and illustrate here.
The roof is sloped towards the drain through either tapered insulation or through joist modifications.
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.
There are roof coating products available if there isn t enough slant or slope to accomplish this.
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.
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.
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.
There are three types of drain systems commonly used on flat roofs.
These will drain to somewhere near the center of the roof and down through the building to underground storm mains or a detention pond.
