How To Waterproof Small Gaps And Cracks In Your Shed Roof

Dealing with a damp and musty shed? Even the smallest gap or crack can let in water, and once it’s in, it doesn’t take long to ruin tools, garden gear, or whatever else you’re storing.

The good news is that you don’t need to replace the whole roof. With Gorilla Waterproof Coat & Seal Spray, you can sort out small leaks quickly and without calling in a professional.

In this guide, we’ll show you exactly how to do it, plus a few tips to help keep your shed dry all year round.

What Causes Gaps and Cracks in Shed Roofs?

Even well-built sheds can develop minor cracks over time. Common causes include:

• Exposure to wind, UV rays, and wind-driven rain.
• Expansion and contraction from temperature and moisture changes.
• Poor quality timber or installation.
• Physical damage from branches, hail, or stones.
  

Note

With wooden sheds, it’s common to see gaps develop where the tongue-and-groove boards meet. They may seem minor, but they are exactly the kind of spots where rain can enter.

What You’ll Need For The Job

• Gorilla Waterproof Coat & Seal Spray
• Clean cloth or paper towels
• Gloves and eye protection
• Masking tape (optional)

How to Waterproof A Shed Roof

Inspect The Area For Gaps and Cracks

Start by checking your shed roof in dry weather. Look for small cracks or gaps in the surface, separation between boards, nails, or fixings, and damp spots or water staining inside the shed.

Clean Your Shed Roof

Next, clean your shed roof’s surface thoroughly. Use a broom or cloth to remove dirt, leaves, and loose debris. If there’s any old paint or sealant, scrape or sand it back to expose a clean surface. The cleaner the area, the better the sealant will stick.

Surface Prepration

For gaps up to 3mm wide, you can go straight in with Gorilla Waterproof Coat & Seal Spray. There’s no need to sand or treat the surface with any additional products as long as it’s clean and dry.

For larger gaps or cracks, fill them first with an exterior wood filler (for minor shallow cracks) or joint backing rod or rope (for deeper cracks).

Once the filler is dry, sand it back so it sits level with the surrounding surface. At this stage, you can also tape off the area with masking tape to help keep the sealant application tidy.

Did you know?

Gorilla Patch & Seal Tape is a convenient, easy-to-use option that can be used to repair roof felt, gutter joints, downpipes, flashing and cracked tiles.

Prepare Your Sealant

Before you begin, always refer to the on-pack instructions for full details on how to use your specific Gorilla product. Additionally, remember to wear appropriate protective clothing and equipment when working with adhesives.

Start by shaking the can for at least 2 minutes to mix the contents thoroughly. Then, test it on a disposable object, such as an old piece of wood or cardboard, to make sure it’s working correctly. Remember that some propellant will dispense with the initial spray.

Apply Your Sealant

If everything is working properly, you’re now ready to start sealing. Hold the can 25 cm from the surface and spray it on in slow, even passes.

Ensure that each gap or crack is fully sealed, particularly around seams, nails, corners, and other areas where water may enter.

Apply a light first coat, let it dry for 10-15 minutes, then apply a second coat. Multiple layers will create a stronger, more flexible seal and are especially useful when working on rough, textured surfaces or old shed roofs.

Let The Sealant Cure & Test For Leaks

Gorilla Waterproof Coat & Seal Spray typically takes between 24 and 48 hours to fully cure.

Make sure you keep the area dry while it cures. If you expect rain or wet weather, cover the area once touch-dry (approximately 1 hour) with a piece of plastic or tarp. Finally, check that the coating is completely cured before testing.

Once the sealant has dried completely, test the area to check whether it’s completely waterproof.

Lightly spray your shed roof with your watering can and check inside for any leaks, drips or signs of moisture. If everything’s dry, job done. If not, dry the area and apply an extra coat over the problem spot.

Ongoing Maintenance Tips

• Check the base. If your shed sits directly on soft ground, water can seep up from underneath. Raise the shed floor slightly, using bricks to help air circulate underneath or install a plastic shed base to stop water ingress.
• Check the inside. Be on the lookout for signs of leaks inside, like standing water, soft patches in the timber, or changes in how the shed smells.
• Check the outside. Inspect your shed roof once or twice a year and reseal any cracks or areas where the coating has worn thin.
• Location matters. If you’re dealing with constant dampness, consider moving your shed, installing a concrete slab underneath, or adding a plastic base. Generally, avoid boggy ground, soggy areas, or clay-like soil that is permanently wet.
• Proper ventilation is important. Poor ventilation can lead to rust and mould, especially during winter months. Make sure you properly ventilate your shed to keep it dry and in good condition year-round.

Why Use Gorilla Waterproof Coat & Seal Spray?

Gorilla Waterproof Coat & Seal Spray is an effective way to seal small cracks and gaps before they turn into bigger problems. Its flexible, weather-resistant formula is made for outdoor use.

• Seals cracks and gaps up to 3mm wide.
• Works on wood, metal, concrete, plastic, and more.
• Dries to a smooth, matte finish.
• Resists UV rays and harsh weather.
• Applies easily without the need for special tools.

It’s a fast, reliable fix for shed roof leaks and a handy product to have on hand for general maintenance.

Top tip:

After using your sealant spray, turn the can upside down and spray until only clear gas comes out. This clears the nozzle and helps prevent clogs for next time.

Keep the Water Out For Good

Fixing small gaps and cracks in your shed roof is a quick job that can prevent much bigger problems later on. A few minutes with the right product now can save you from dampness, mould, and damage down the line.

If you found this guide helpful, check out the Gorilla Glue Blog for more DIY tips, repair guides, and smart ways to keep your outdoor space in great shape.

‍