Are overflow scuppers required?

Asked by: Komkrit Collins

1 Secondary (emergency overflow) drains or scuppers. Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason.

Is a scupper a drain?

Definition of Roof Scupper



Roof scuppers are not the same as roof drains. Roof drains channel water through the deck of the roof into a piping system that carries water away, while a scupper allows water to drain through an opening in the side of the roof edge.

What are scuppers and downspouts?

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.

What are scuppers used for?

A scupper is an opening in the side walls of a vessel or an open-air structure, which allows water to drain instead of pooling within the bulwark or gunwales of a vessel, or within the curbing or walls of a building.

Where do you place scuppers?

They are typically installed at a point in the parapet wall that is as close as possible to the primary drain for that area. 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 a scupper overflow?

Overflow drainage scuppers are typically holes with no downspout or other intricate designs. This is because these scuppers are specifically designed to remove water when there is a blockage in the primary system. Overflow drains can be used with roof drains or with primary drainage roof scuppers.

How do you install a roof scupper?

Using the appropriate screws. Weld along the interior edge of the metal flange on your first pass to secure the scupper in place. Continue the weld around the perimeter of the target flaps.

How do roof scuppers work?

On flat roofs and in parapet walls, scuppers function essentially as a continuation of the roof membrane. Scuppers install into perimeter curbs and parapet walls on your roof and carry water from the roof, through a wall and then down the side of the building.

What is a scupper in plumbing?

In short, a scupper is a detail that provides drainage to a roof system by allowing the water runoff from the roof to exit the roof through a metal edge, parapet wall or through the deck into a downspout or leader not run through the interior of the building.

What is a roof overflow drain?

Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason.

How do I stop water sitting on my flat roof?

Tapered polyisocyanurate (also known as tapered iso) is a type of flat roof insulation with built-in slope. Tapered insulation is used to strategically prevent ponding water because the slope helps the flowing water and debris navigate towards a roof drain.

How many drains do I need for a flat roof?

Take the roof’s total square footage and divide by the total square footage handled by one drain. The result is the number of drains needed. For example: 50,000 / 4,400 = 11.36; or 12 drains required.

How do flat roofs handle rain?

Gutters are the most commonly used drainage system when it comes to flat roofs. Just like the gutters installed on sloped roofs, these marvels catch rainwater and divert it into a downspout, which carries it away from the foundation.

Do I need guttering on a flat roof?

Most modern flat roofs are covered by a membrane that prevents water leaking into your property. But if your roof has a slight slope it will need gutters to ensure proper drainage.

Do flat roofs need drainage?

Flat roofs require specific and stringent drainage requirements to make sure that the rainwater is directed off the roof effectively. Without enough of a slope, and without adequate drainage, water will instead gather and pond on the top of your roof, which can cause chaos for your roof structure.

Do all flat roofs have drains?

Because of the nature of their design, flat roofs do not have the natural drainage that sloped roofs offer, where gravity is working to remove water build-up. It is essential that flat roofs are fitted with an effective drainage system to ensure they are removing any moisture from the roof, to avoid serious damage.

Where should a roof drain be placed?

Location – Drains SHOULD NOT be next to other rooftop objects like A/C units, vent pipes, or skylights. Level – Drains SHOULD always be installed at the lowest level of the roof surface. Strainers/Domes – Drain strainers SHOULD have holes or openings large enough for small debris to pass through.

What is the height of an overflow drain above a roof drain?

2 inches

Overflow drains, located 2 inches (51 mm) above the roof drain inlet, are required by Section 1506.3 where parapets or other conditions will cause ponding if the roof drain is inoperative.

How far apart should roof drains be?

When placing roof drains, it is good design practice to locate the drains no more than 50 feet from the roof perimeter, nor more than 100feet apart. 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.

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.

At what slope does water flow?

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.

What slope is considered a flat roof?

1-10 degrees

A flat roof is generally any roof with a pitch of 1-10 degrees. That means flat roofs aren’t actually flat. It may look horizontal but often has a minimum slope of 1/4 inch per foot. This allows water to run off the roof to prevent damage.

At what angle does water flow?

Since water finds its own level, even a 1 degree slope will allow water to run, but it is generally better to to pitch your roof 15-30 degrees for efficient running of water to avoid water soaking into the roof and leaking.

What is the best angle for a roof?

Conventional slope roofs, with a pitch between 4/12 and 9/12, are the most common in residential work. Roofs with a pitch exceeding 9/12 (37 degrees) are termed steep slope roofs. In commercial work, low-slope roofs (with a pitch between 2/12 and 4/12) are most common.

What is the lowest slope for a metal roof?

The minimum slope for a metal roof with exposed fasteners and seams without sealant is 3:12, which means 3” of drop for every 12” of horizontal run. Roofing with exposed fasteners and lapped seams with sealant can go lower – ½:12.