Soudal silicone meets leaky gutter—finally, a fix even cautious DIYers can trust fully

June 24, 2025

Gutter Sealing 101: How to Stop Leaks the Smart, Simple Way

The unexpected DIY skill that protects your home from costly storms—and keeps your weekend plans intact

When it rains too hard and your gutters give up, you don’t just get drip-drip from the corners. You get rust, rot, mould, and the kind of damage that turns a quiet Sunday into a full-blown repair mission. Guttering isn't glamorous, but get it right—and it may just be the reason your fence posts, garden beds, and shed stay standing another decade.

"I used to dread fixing gutters until I sealed one properly—it’s been 18 months and not a single leak since." — Candeece from the Tool Desk

In today’s guide, we’ll show you how to seal a leaky gutter the right way: quick, solid and built to outlast another summer storm. Bonus? You’ll only need one tube of silicone and about 20–30 minutes of your time.

Before We Begin: What Causes Gutters To Leak?

It’s a short list, but it packs a punch:

Corrosion or rust holes in the metal
Separated joints where two gutter segments meet
Cracked seals around downpipes or end caps
Blockages that cause water overflow and wear down the joins over time

Sealing a leak fixes the symptom. Pair this with a gutter clean or guard-down treatment and you’ve just extended your system’s life by years.

Here’s What You’ll Need:

Gloves and safety glasses
Dry rag or towel
A suitable all-weather sealant, like Soudal All Purpose Silicone 300ml
Caulking gun
Soudal Cleaner & Degreaser to prep the area
Paper towel or soapy rag for smoothing the seal
Ladder (always follow safety precautions)

Step-by-Step: How to Seal a Leaky Gutter

1. Choose a dry day—and let everything breathe

Wait until your gutters are bone dry. Sealant won’t bond properly if there's moisture, condensation, or even humidity hanging around.

2. Scrub it good

Use a rag and Soudal Cleaner & Degreaser to wipe down the inside of the gutter. You’re aiming for a rigid, dry, degreased surface with no peeling old sealant or flakes of rust.

3. Apply the sealant like a pro

Load up your caulking gun with Soudal All Purpose Silicone. It’s the sort of silicone that clings to just about anything—aluminium, zinc, powder-coat, even timber—and stays watertight through heat, UV, and heavy rain.

Above all, don’t skimp at the join. Push the nozzle into the crack or joint and fill it in slowly, pulling the gun along evenly. Once applied, use a finger or paper towel to smooth the bead across the join—it’ll help it lock in better and look cleaner too.

4. Let it set—and stay off your ladder for now

Leave the gutter alone for at least 24 hours to properly cure. The sealant will stay flexible, mould-resistant, and clear of yellowing if you let it do its job before the rain returns.

Tips From The Locals

“Seal from inside the gutter, not outside. That way water pushes into the seal, not away from it.”
“Works way better if you wait until late morning. That winter condensation is sneakier than it looks.”
“I do mine every other year just to be safe. Prevention always wins.”

Yes, It’s That Easy—But Only If You Use The Right Stuff

Here’s where the magic lies. You could grab any ol’ tube of silicone. But many don’t work on oxidised aluminium or weathered timber. And some degrade fast under full sun—cracking just when you need them most.

Soudal All Purpose Silicone isn’t just a patch—it’s a long-term fix. We stock it for a reason: UV-hardy, neutral cure, mould-resistant, and sticks to most surfaces like it was made for them. Even after our last proper downpour and 65km/h winds? Still sealed tight.

Behind Every Good Gutter Is A Bit Of Quiet Preparation

If there’s one takeaway here, it’s this: sealing a gutter isn’t about perfection—it’s about prevention. And the difference between a weekend spent making pancakes or one balancing precariously on a ladder under drizzling skies? Often comes down to 10 minutes, one tube of silicone, and the habit of checking your home’s quiet corners before they get loud.

Take it from someone who’s spent more Saturdays upside-down in a pair of muddy Blundstones than she cares to count—when it comes to DIY, a little proactive effort is the easiest way to protect what matters most.

Happy sealing,
Candeece