How To Do Roof Drainage

The guide gives rational to the whys and hows of allowing free drainage.

How to do roof drainage.

To put it simply scuppers are openings in the outer walls or curbs along the roof line. 2 3 4 5 6. A siphonic roof drain utilizes siphoning as a drainage mechanism resulting in drainage that is faster than that on any other type of roof drain. For most single family residences the roof is pitched allowing rainwater to flow by gravity to a gutter system and discharge to grade.

Determine leader or pipe size. One of the main concerns that small scale builders have outlined to us is how to drain the roof. A french drain is a small trench with a perforated pipe surrounded by sand or gravel that directs the water flow away from the foundation following the grade. Be sure there is an adequate and appropriate number of drains for the size of your roof.

Ipc provides four steps to size the roof drains on a building. See french drains for details of handling roof runoff at flat or poorly drained sites. Calculate the total roof area by multiplying its length by width. Stormwater flows away from the building naturally to storm drains or in some cases to the street.

Before commercial drainage layers were developed it was common practice to use a thin layer of gravel to act as a drainage layer. Where the tube passes by the downspout from the gutter we installed a y fitting and drained the roof water from the gutter system directly into the main drainage line. Step by step instructions step 1. Siphonic roof drain.

Commonly used on flat commercial roofs siphonic drains allow for a minimal number of drains and all of the drains can be connected to a single leader. Gravity drainage stormwater simply drains off the roof and other areas to the ground. 2 3 4 5 6 and 8 in. They catch rainwater as it rolls off the edge of the roof and divert the water into a downspout that dispenses it a safe distance from the foundation of the building.

Determine 100 year 1 hour rainfall rate used for location of building select number of roof drains and calculate the roof area sloped to each drain size horizontal storm drainage piping. Calculate total roof area. Taking care of your drainage. Screw a drain cover over the end of the tubing as it approaches daylight to keep critters out.

Gutters are the most commonly used and most cost effective drainage solution for flat roofs. They allow water to run through the wall via a metal box protecting and surrounding the scupper. How to drain the roof. Not only will it get the water away from the house but it will also do it without any possibility of water runoff damage or erosion.

To prevent erosion make a rock bed around the end of the tube.