Soudal Silicone just saved my shed roof—ever sealed a stormwater pop wrong before? Oof.

June 25, 2025

Sealing Stormwater Pops Just Got Easier (and Neater Than You Think)

How to choose the right sealant when connecting stormwater to your roof gutter

"Wait, what do I use to seal this thing with?" If you've ever stood in your driveway, stormwater pop in one gloved hand and a gutter in the other, you’re not alone. It’s one of those DIY moments where things get messy fast—literally—if you choose the wrong product or skip the prep.

The good news? There is a right way to seal a stormwater pop into a gutter, and once you know it, you'll never look back. It's like learning the perfect biscuit-to-cuppa dunk ratio: oddly satisfying and surprisingly handy forever.

Before: Leaks every time it rains.
After: One clean, watertight seal that lasts for years.

The secret lies in what you don’t see

Sealing where your stormwater pop connects to your gutter isn’t just about stopping water from going the wrong way—it’s about protecting what’s underneath: the fascia, eaves, and even your garden or shed from water damage.

Here’s the thing: standard silicones just don’t cut it outside. Sun, rain, frost—all of it breaks them down over time. That’s where Soudal All Purpose Silicone 300ml comes in.

This isn’t your average tube of goop. Soudal’s neutral cure silicone is:

Super sticky – it grips PVC, aluminium, galvanised steel, and even painted surfaces.
Mould-resistant – because nobody wants a black slime ring around their downpipe.
Permanently flexible – so it shifts with heat and cold without cracking.
Weatherproof – designed to handle the four-seasons-in-a-day drama we all know too well.

What you’ll need:

Stormwater pop (sized for your downpipe—usually 90mm)
Gutter with outlet hole pre-cut
Soudal All Purpose Silicone 300ml
Caulking gun
Clean rags or paper towel
Soudal Cleaner & Degreaser for prep

Step-by-step: No leaks, no stress

Clean everything. Use Soudal Cleaner & Degreaser to wipe down the inside of the pop and the cut edge of your gutter. It’ll help the silicone bond properly.
Apply Soudal silicone – run a bead around the inside flange of the pop, about 5mm from the edge.
Fit the pop into the hole in your gutter and press down firmly. Wiggle it slightly to seat it evenly.
Smooth the sealant – using a gloved finger or silicone tool, neatly shape the bead for a watertight finish.
Let it cure – give it 24 hours before letting water run through.

The trap most people fall into...

They skimp on prepping the surface. Whether it's an old tin shed or a new garage reno, skip the cleaning stage and no sealant—no matter how brilliant—will hold properly.

That’s what makes this job feel frustrating when it shouldn’t be. Like putting icing on a hot cake—it looks good… for all of 30 seconds.

Real talk: What happens if you don’t seal it correctly?

Sure, you’ll probably get away with it during light rain. But after a few months? Water seeps between the gaps, corroding metal, encouraging mildew in your walls, and potentially giving your fancy eaves a fungal moustache you didn’t ask for.

It's the kind of slow damage that's hard to see—until you're replacing roof battens or repainting soggy fascia boards.

Seen it done wrong?

I remember helping someone reconnect a shed stormwater setup last spring. They had used construction adhesive thinking stronger was better. Six months later, the adhesive cracked, water started pooling near the entry door, and they had to rip out the entire bottom gutter. Lesson? Just use the right product from the start—and don't overthink it.

Why Soudal works where others fail

“Most sealants say they work in all weather but crack under UV or temperature shifts. Soudal doesn’t flinch—it was made for outdoor battlers.”
– Candeece from Strath H

And whether you're sealing around roofing sheet joins, a gutter bracket, or a pop—Soudal works across the board. It even bonds well to timber, fibreglass and laminate, making it a bit of a DIY all-rounder.

And here's the clincher:

If you're sealing stormwater in anything exposed to weather, always choose a neutral cure silicone built for the job—it’s the difference between a weekend job and a yearly patch-up chore.

Right tools, right prep, right technique. That’s the trifecta every tidy project is built on.

Happy sealing,
Candeece 🛠️