How high should overflow scupper be?

Where you must drain through the wall with a scupper the overflow must be three times the required size of the roof drain and have a minimum height of 4″ and again be installed no more than 2″ above the roof low point. While you must provide the overflow it can not be connected to a downspout.

What is the minimum height above finished grade for the secondary roof drain system?

If they are used for secondary drainage, then they should be a minimum of 2 inches above the roof level and a maximum of 4 inches above the roof level.

What are scuppers on a roof?

Description: Scuppers are used to provide an outlet through parapet walls or gravel stops on flat and built-up roofs to allow drainage of excess water. They can be used in conjunction with gutters and downspouts to divert the flow to the desired location.

Where do you place scuppers?

Scuppers are installed at the perimeter of the roof area and can be located at openings in parapet walls and/or openings in the perimeter metal. Scuppers can be used as primary or secondary (overflow) drainage. Proper flashing details are required at scuppers to prevent moisture infiltration into the roof system.

How big should a scupper be?

Roof Scupper Size The only unconditional guideline for roof scupper sizing provided by the code is that “scupper openings shall be not less than 4 inches (102 mm) in height and have a width that is equal to or greater than the circumference of a roof drain sized for the same roof area.”

How many roof scuppers do I need?

It is important to remember that no roof area should ever have less than two roof drains. Size and placement of rooftop equipment may necessitate additional roof drains. Consideration should also be given to local codes whish may require separate overflow drain systems.

What is the minimum slope for drainage on a roof?

For drainage purposes, the current building codes require a minimum two percent slope or a one-fourth unit vertical for every 12 units horizontal. In other words, the roof must slope one-fourth of an inch for every 12 inches. The slope is barely noticeable to the naked eye.

How do you size scuppers?

What does a scupper look like?

Channel-type scuppers are three sided or are a simple rectangular hole cut in the wall. Some types can be round or a unique, decorative shape using custom sheet metal fabrication. These holes allow any water to drain straight down the sides of your building to prevent standing water and leakage.

How do you size a scupper opening?

The only unconditional guideline for roof scupper sizing provided by the code is that “scupper openings shall be not less than 4 inches (102 mm) in height and have a width that is equal to or greater than the circumference of a roof drain sized for the same roof area.”

How do you calculate a scupper size?

To adjust this table for other than a 5-inch design rain fall rate, multiply the square footage on the table by 5 then divide by the local design rain fall rate. Example: For 4 inches of design rainfall rate, a 4-inch long scupper with a 1-inch head would accommodate 287 square feet. (230 x 5) ÷4 = 287.

How much of a slope does water need to run?

Pipes must slope slightly downhill to drain properly. The standard slope is anywhere from ¼ inch to 3 inches per foot depending on the use. An accurate calculation is essential for properly functioning plumbing.

How many square feet can a 4 roof drain handle?

Example: For a 4″ hourly rainfall and 4″ leader, each drain can handle 4,600 sq. ft. of roof area.

What is a scupper overflow?

The overflow scupper is located as close to the primary drain as possible so that it will drain the same roof area that the drain does if the drain becomes clogged.

What is the minimum slope that flat roof should have to drain rainwater?

For drainage purposes, the current building codes require a minimum two percent slope or a one-fourth unit vertical for every 12 units horizontal. In other words, the roof must slope one-fourth of an inch for every 12 inches.

What is an overflow scupper?

Scuppers provide a pathway for water to flow through parapet walls or any other raised edge around a roof, such as a gravel stop edge metal. Primary scuppers normally channel water off the roof into a conductor box that connects to a downspout or a gutter. Overflow scuppers will let the water run freely down the side of the building.

Are scuppers an acceptable form of roof drainage?

Scuppers shall not have an opening dimension of less than 4 inches. The flow through the primary system shall not be considered when locating and sizing scuppers. This code implies that scuppers are an acceptable form of roof drainage.

What is the size of a scupper on a roof?

When scuppers are used for secondary (emergency overflow) roof drainage, the quantity, size, location and inlet elevation of the scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by Section 1611.1. Scuppers shall not have an opening dimension of less than 4 inches.

Can you put a scupper over a downspout?

Where you must drain through the wall with a scupper the overflow must be three times the required size of the roof drain and have a minimum height of 4″ and again be installed no more than 2″ above the roof low point. While you must provide the overflow it can not be connected to a downspout.