Have you heard the term “leader head” but aren’t sure what it actually does (or if you even need one)? Worried your roofer might take the cheaper route, which could cause thousands in water damage later?
You’re not alone. Most Seattle homeowners don’t even know what a leader head is—until it’s too late. If your roof has a tricky drainage setup or a flat roof with scuppers, one small design flaw could be silently channeling water into your walls, attic, or roof deck.
At RoofSmart, we’ve repaired and replaced hundreds of flat roofs across the Seattle area. We have seen the damage that leaks around drain points can cause over and over again. We often recommend installing leader heads to our customers with flat roofs because we’ve seen how much better they work than cheaper alternatives.
In this article, we’ll break down exactly what a leader head does, why it matters in a rainy climate like Seattle, and how it compares to alternatives like through-wall scuppers.
You'll learn what to watch out for and how to make the right drainage decision before your roof turns into a costly repair nightmare.
Why should I install a leader head on my Seattle roof?
Leader heads (also known as a conductor head or scupper box) are part of the water drainage system on a roof. Not every roof requires a leader head, but they can make draining rainwater off the roof safer and more efficient.
Sometimes they are fancy and decorative, while others are simple. They can serve a functional purpose while also elevating the curb appeal of your home (the one pictured above is very simplistic).
They can be built to any style or shape you need, making leader heads a flexible solution. So, if you've got a funky spot or a weird corner, you can manufacture one of these things to fit how you need them to.
They are made out of aluminum or copper. Copper is a more expensive metal, so that usually used for fancier, more decorative leader heads. Aluminum is a cheaper option that still offers great quality.
Does every Seattle roof need a leader head?
In some cases, roofers will install a through-wall scupper instead of a leader head. This is similar to a leader head, but the big difference is that it sits in the wall. Here’s an example:
It’s important to note that because the through-wall scupper sits in the wall, it increases the risk of leaks and other damage. It’s difficult to properly seal everything within the wall, so there’s a higher risk of mistakes or poor workmanship.
Leaks in the through-wall scupper can lead to rotting wood, mold, and structural damage. These types of leaks can stay hidden for a while and cause extensive damage.
For example, we had a recent customer with a lot of through-wall scuppers on multiple different levels of his flat roof. Here’s one of many damaged corners where a through-wall scupper had been installed:
They had been leaking like crazy, and basically all of the wood was rotten and moldy. The worst part is that this type of leak damages your roof and your walls, so you’ll have to replace big portions of your house to fix all of the damage.
Another issue with through-wall scuppers is that they clog very easily with leaves and other debris. Here is the view from above of a clogged through-wall scupper:
If you don’t clean this out, it can cause water to back up and get into the walls. It’s not that difficult to clean out, but you really have to stay on top of it to prevent worsening clogs.
What are the benefits of using a leader head in Seattle?
In a rainy, damp area like Seattle, it’s crucial that your roofer takes the necessary precautions to protect your roof from leaks and water damage. And that’s exactly what having a leader head does for your roof and walls.
The idea behind a leader head is that it is all external, so water is not traveling through your ceiling or walls. It immediately goes to the downspout.
This design helps to prevent all of the problems caused by through-wall scuppers, including:
- Leaks
- Rotting wood
- Mold
- Structural damage
Repairs for mold and rotting wood can easily cost thousands of dollars. If the leak has time to spread further through the roof and even damage the siding, then you might be looking at tens of thousands of dollars for a repair.
Unfortunately, flat roof repair costs can quickly increase because so much of the damage is hidden.
How do I decide if a leader head is right for my roof?
Leader heads can be used on flat or sloped roofs, but they’re usually more of a decorative piece for sloped roofs. You can install decorative ones to elevate the curb appeal of your home. This is typically an extra expense because regular gutters work fine on most sloped homes.
On the other hand, they can be a useful tool for protecting your flat roof from damage. A through-wall scupper is a cheaper option, which is why so many flat roofs have it. But it comes with a higher risk of damage.
A leader head costs more, but you’re investing in better protection for your roof and siding. It's only a couple hundred bucks extra (while you’re installing the roof).
Repairing the water damage from a leak will cost you thousands of dollars (and a few hundred extra to then install a leader head).
Ultimately, it’s a decision of how much you want to spend on your roof now and how much of a risk you’re willing to take on having future damage.
Could poor drainage be hiding bigger installation problems in my flat roof?
Choosing the right drainage solution (like a leader head instead of a through-wall scupper) can protect your home from expensive water damage. But even the best drainage system can’t save your roof if the membrane itself was installed incorrectly.
If you have a flat roof, it’s critical to make sure the entire system was installed the right way (flashing, seams, and all).
Unfortunately, in the Seattle area, we see a lot of flat roofs that look “fine” at first… until leaks, ponding, or seam failures show up months (or even years) later.
Wondering if your flat roof was installed correctly, or if hidden shortcuts could be putting your home at risk? Find out in our article: “Was My Flat Roof Installed Correctly in Seattle?”
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