Rainy Season? Find Out How To Waterproof A Shed Roof

For many people, a garden shed is a place where you can spend hours and hours tinkering with gadgets and fixing tools. That’s why when the rainy season arrives, it’s important to weatherproof and waterproof your shed from top to bottom and ensure that the inside is totally protected from water intrusion, leaks, dampness, mould and other problems that bad weather can bring.

A garden shed with rake, grass cutter and other gardening tools

Waterproofing is not a difficult task, and you will learn below how to waterproof your shed roof all on your own with easy steps so that your shed is well protected from the outside elements!

Why waterproofing is important

Water is the enemy of sheds, to say the least. Allowing water to leak in can not only harm the garden building by causing rot and mould, but it also puts your possessions at risk. Water can wreak havoc on wood in particular. Even water-resistant types of wood, such as cedar, aren’t waterproof by nature. 

Water is still a concern even if you reside in a dry country region. Rainfall occurs in every city and town across the UK, and even small amounts of moisture can destroy your new shed. If you wish to keep rainwater from saturating your belongings, you must take action.

How to check for signs of leaks

The best time to inspect your shed for leaks is after it has rained. Rain will typically hit the majority of the outside surfaces, allowing you to spot a wider range of potential issues. Furthermore, if you check right after a rainstorm, water will still not have completely evaporated, so you can miss out on important information if you wait too long.

The most obvious indicators of a leak are damp spots and yellowing of the wood. If any of your belongings are damp, it’s a sign that there’s a problem. To determine the source of a leak, follow the water flow, especially if there are puddles near the shed walls or drips coming from the ceiling. You must, however, separate condensation from leakage. Drips can form when moisture in the air comes into contact with a cold surface, and so you don’t need a leak to have condensation.

Roofing materials to consider

There are several materials you can choose from to waterproof roofs. You can use special roof membranes, or other materials that are water resistant. Let’s  see some of the most common.

1. EPDM (ethylene propylene diene terpolymer)

EPDM rubber roofing is inexpensive, long-lasting, and simple to install. It’s also completely watertight. There are no seams or locations where water can leak because it arrives in one huge sheet. It is also environmentally friendly and provides UV protection from the sun’s rays.

2. Felt

Traditional roof felt is the best shed roof material available. However, its advantages are limited to its low price.

Installing roof felt in the rooftop of a garden shed

3. Metal shed roofing

Metal roofing sheets are a reasonable solution for ensuring that your shed remains waterproof. Corrugated sheets or underlays are both options for metal roofing.

4. Wood shingles

Wood shingles are created from various woods, including redwood, cedar, and oak, which are the most expensive.

5. Clay tiles

Clay roof tiles might be an excellent choice if you have a sturdy or large wooden shed base that can withstand the outside elements. They are pleasing to the eye, have a lovely aesthetic appeal, and are long-lasting and sturdy, with a lifespan comparable to EPDM. With modern technology, DIY installations have gotten easier, and they are available in various forms and styles.

How to waterproof a shed roof step-by-step

Step 1: Raise the shed off the ground

Use cinder blocks or other stone shed supports to keep it off the ground or create a framework out of treated wood. Groundwater cannot soak into the shed because it is built on supports. If your shed is currently sitting on the ground, your options are restricted, though. 

You may elevate the shed with heavy gear and then put a support structure underneath it. Most sheds built by professionals are raised off the ground, so there should be no problem here.

Step 2: Paint the outside of the shed with a waterproof paint

Go to your local hardware or home improvement store and choose a paint that says “waterproof” on the packaging. Paint the shed’s whole exterior, including the roof and all four sides.

This forms a water-repellent barrier, which prevents the water from being absorbed. If you’re painting the flat roof while it’s being felted, do so between washing the roof and adding the fresh felt.

Step 3: Fill gaps in the shed with caulk

Get a caulking gun and some all-purpose caulk. Look for any gaps across the shed’s corners and edges or crevices between the boards on the walls and ceiling, and then use the filler to fill any holes you see.

Step 4:  Make sure doors and windows are properly sealed

Always close the doors and double-check that they are securely fastened to the shed so that nothing goes in. If the shed has windows, ensure they are shut tight whenever you are not using it. Look for any gaps around doors and windows and apply a silicon or other waterproofing filler if necessary.

Step 5: Apply weather-stripping materials around doors and windows

Add foam seals to your windows and doors if they don’t already have them. Foam weatherstripping is often sold in rolls and is simple to install around door frames and windows. It establishes a seal between the building’s frame and the gaps between doors and windows.

Step 6: Insulate the inside of the shed

The insulation forms a watertight barrier around the shed’s interior structure. Attach the insulation to the shed’s support studs rather than the exterior OSB panels. 

Bubble wrap is a cheap and effective technique to insulate a shed, although normal fibreglass insulation can also be used. Stapling insulation to the studs helps decrease moisture by creating a small airflow between the exterior panelling and the insulation.

Roll of bubble wrap

Step 7: Measure the roof’s surface area

Measure one side of the roof’s length and width and then multiply that number by two to get the total roof area if the shed is a simple A-frame.

You’ll need to set up a step ladder or a telescopic one to go to the roof. It’s also a good idea to have someone on the opposite end of the roof to assist you. Make a mental note of the numbers, so you don’t forget them.

Step 8: Obtain roofing felt for your shed

To ensure that you get enough felt to cover the entire roof, use the roof area numbers you jotted down when you took measurements earlier. If you have a variety of roof felt selections, you’ll have to pick the one that fits your budget and appears to be in good condition.

Step 9: Remove any existing shingles

Ascend the ladder with a scraper of some sort. The most effective scraper is one mounted on a long pole. Place the scraper beneath the old shingles and move it forward and backwards to loosen the roof covering. This can take time if they are nailed or glued down tightly. Once you’ve removed all, make sure to throw them away.

Step 10: Clean the roof’s surface and remove any nails

Pull any crooked nails using a claw hammer or another nail removal tool. You can leave any nails that are flush with the roof decking in place. If the surface appears dirty, wipe it down with a moist rag.

To avoid nails ending up in your yard, dump them into a bucket or garbage barrel. If you leave loose nails on the ground, they can pop mower tires or end up in someone’s foot.

Step 11: Apply a coat of weatherproofing paint or primer to the roof

Even if you’re covering the roof with felt, the paint or primer will add an extra layer of sealant.  Ideally, you should paint the roof simultaneously as the rest of the shed or separately if you’re concentrating on felting the shed.

Step 12: Place the first piece of felt along the roof’s bottom edge

Roll the felt horizontally along the roof’s length. Make sure the felt is hung about 2 cm above the edge of the roof to allow water to run off. The number of pieces of felt you need to lay depends on the width of the felt rolls you bought and the size of the roof.

nailing a piece of roof felt on a garden shed's roof

Step 13: Use galvanised clout nails to secure the felt

Although the sort of nail you choose is up to you, it’s important to use galvanised nails to avoid rust. To keep the felt in place, pound nails into it as you unroll it. Nail across the whole circumference of the felt, approximately every 30cm. To guarantee that the nails get through the felt and fasten into the ceiling, use about 20mm long nails.

Step 14: Place the second piece on top of the first

Unroll the second piece of felt horizontally. To facilitate water flow, make sure it slightly overlaps the first piece and then hammer the second piece of felt in place.

Step 15: Nail the felt to the second side of the roof

Cover the second side of the roof in the same way as the first. Start at the bottom, with one piece of felt dangling over the edge and then hammer the felt in place as you go. Make sure each component is overlapping the one before it.

Step 16: Overlap both sides of the roof with a last piece of felt centred over the pinnacle

Lay one more piece on the roof’s top point after both sides have been felted. It’s not necessary to use a piece that spans the entire width of the roll. Cut it to about 30 cm in length, making sure it covers the apex crack and overlaps both sides of the roof.

a garden shed

While waterproofing a shed is time-consuming, it will considerably increase its lifespan. Water damage can cost hundreds, if not thousands, of quids to repair, so waterproofing is well worth it. You use a shed to store things and keep them safe, so it is time to keep your shed safe as well!

Next project: Learn how to build a pitched roof extension DIY.

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