Scuppers – Flat Roof Repair

Scuppers for flat roofs

Scuppers flat roof repair - they were letting debris through to clog the leader header
This scupper is way to small for the size of this flat roof

Scuppers flat roof repair – The cause of a major leak was due to incorrect leader headers on the other side of the wall. Scuppers are perfect for getting water off a roof, but if water flow is restricted and water backs up into the scupper again, that will cause leaks.

Here is the Merriam Webster definition for SCUPPER.

Scuppers Flat Roof Repair

Scuppers Flat Roof Repair – This image shows what the scupper opening at the bottom.  There are 2 of these scuppers on the same wall. There are several issues we have found that causes leaks around these scuppers.

Besides the scupper at the bottom of the image, also notice the stucco has deteriorated, and the cement block is showing through. The cracks on the wall will cause leaks, and it will appear on the roof.

Wall where Scuppers and Leader Headers are mounted

The image shows the wall where the scuppers exit into the leader headers. All the water from the flat roof of the other side of the wall drains through these scuppers and leader headers. Debris washes through the scuppers into the leader headers. The strainers catch all the debris causing a blockage.

Here is a list of issues:

  1. Leader headers are not attached properly to the wall
  2. The leader headers had strainers inside them that blocked the drainpipe with little debris
  3. Someone has added an extension to the leader header making it higher than the scupper, compromising the emergency overflow in case the drainpipe got blocked.
  4. Scuppers are not sealed properly to the wall – water will leak in easily.
  5. Flashing on the wall is not attached properly
  6. No strainers on the inside of the wall to prevent debris flowing through the scuppers blocking the drain pipe.
Outside wall from flat roof with scuppers and leader headers
The two scuppers shown from the outside wall

Leader Header not attached to the wall

When a leader header gets blocked with debris, it will separate from the wall causing water to flow down the wall instead of overflowing the rim of the leader header. Scuppers and leader headers have to work together.

Scuppers flat roof repair - Leader Header not attached to wall causing scupper to leak
This is what was causing problems on the outside wall of the scupper. The leader header of the down-pipe

Extension piece added to leader header causing water to rise to high into the cupper

A leader header should always be lower than the scupper. If the drain pipe gets blocked or debris gets stuck in the leader header, then water backing up can spill over the leader header instead of pushed back into the scupper and the wall.

In the image, the scupper is not sealed to the wall and therefore when the blocked leader header fills with water, the water leaks into the wall around the scupper.

In the image notice, the extension piece added on top of the leader header. When water backs up, it forces the water into the wall and the through the scupper onto the roof.

Scuppers Flat roof repair - Extension piece added to leader header causing water to rise to high into scupper
Placing a leader-header on the outside of a scupper is not a very wise idea. This will cause debris to accumulate clogging the pipe backing up the scupper

Strainer in leader header causing a blockage – forcing water onto the flat roof through the scupper

The strainer or filter in the images was placed in the neck of the leader header, causing to clog fast with a small amount of debris. Because of this, water backs up onto the flat roof through the scupper. The extension on the leader header added to more problems.

Strainer Causing blockage in leader header - that caused a major roof leak
To make matters worse, a leaf filter was placed inside the leader-header. All the debris that came through the scupper got caught in the leader=header.

Debris getting through scuppers blocking drain causing the leader to fill with water

Scuppers and leader headers get filled with debris very fast. If the scupper were letting the water of the roof without a leader header to catch the water, then it would be fine because the debris will get washed off the roof.

Since there is a leader header funneling all the water into a drain pipe, then it is important to have a strainer to the mouth of the scupper. Strainers should allow small debris through and stop twigs and leaves.

Watch this video on Drains and Strainers

Debris blocking the drain causing leader to fill with water

Scupper, and leader header issues force water into the flashing around the scupper and leader header

When water was backing up due to a blocked drain pipe, the water then was forced onto the wall into the flashing.

With a heavy rain hitting the wall this would also cause a leak.

Flat roof repairs always have to do with draining systems. Make sure when you have your flat roof repaired that the drains get particular attention.

Water was forced into the flashing around the scupper and leader header

Flashing above scupper causing leaks

Flashing above scupper is not properly attached to the wall. This also causes leaks.

Flashing above scupper causing leaks

Flashing above scuppers and leader headers are leaking

In the image, the flashing is not sealing properly into the stucco wall. With a heavy rain blowing onto the wall, water will leak into the building.

flashing above scuppers and leader headers are leaking

Flashing on wall causes leaks on a flat roof

A closer look at the flashing shows where water is leaking in.

flashing on wall causes leaks on a flat roof

Cracks on the wall cause flat roof leaks

The stucco on the wall has deteriorated and caused the cement block to crack. This is just another issue on the flat roof where water leaks on.

Cracks on the wall cause flat roof leaks

Flashing on stucco wall need repair

Flashing on the wall need re-installing, because water can leak through that area. Flashing on a flat roof makes or breaks a roof. All the issues in the images above have to do with flashing. Most workers do not pay close attention to flashing and cause more harm than good.

Flashing on stucco wall need repair

More flashing issues that could potentially cause leaks

Most roofs and leaks are due to flashing not properly done. For the most part, it is inexperienced people trying to do a job. The other reason is that they under bid a job and try to seal it with caulking or something and hope to get away with it.

More flashing issues that could potentially cause leaks

If you got this far reading and looking at all the issues we have mentioned, you might want to take care of this electrical wire that open.

Electrical wire need attention on flat roof repair

Scuppers Flat Roof Repair

A list of what to do:

  1. Replace leader headers with new ones
  2. Install a rubber membrane gasket around the scuppers facing the leader headers
  3. Seal the flashing
  4. Install a rubber membrane over the areas on the wall where the cracks are
  5. Custom make large strainers to be mounted in front of each scupper
scuppers flat roof repair - leader header
Please write a Review on Roof Leak Repairs
Please write a Review on Roof Leak Repairs at the bottom of the page

5 thoughts on “Scuppers – Flat Roof Repair”

  1. I had a major leak inside exterior wall under the scupper. Roofer thinks water was building up or splashing off leader header and through the stucco wall undernith the scupper. Thinks wall around scupper is not sealed properly. I see no evidence of water running down the exterior of wall. Is it possible that water travelled from leader box, along underside of scupper, directly through the wall? Roof is not leaking.

    1. Absolutely. The most common leak on a scupper is how the roofing material is attached to the metal scupper. I am almost 100% sure that the rubber material is not properly attached to the scupper. You should be able to look from the outside of the wall into the scupper and see the rubber. Take a screw driver and see if you can pry the rubber up. Then you will see the leak.

  2. We are building an addition to our house. Addition will have a flat roof. Our budget does not allow us to install green roof (less than 400 sqft) but we hope to install it in once we save enough. What clearance should we build for the roof to accommodate future not intensive green roof.

    1. Naas Ferreira

      Ok, I am not sure what you are referring to as “Clearance”. Clearance to what? What I suggest is to always make sure that the flat roof surface is always 4″ or more lower than the door sill.

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.