How to Waterproof a Shed

Sheds, Conservatories & Outbuildings
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How to Waterproof a Shed

Once the wetter weather hits, it’s always a scramble to make sure your house is well-protected against water ingress, leaks, damp, mould, and other issues adverse weather can cause. However, many often overlook other parts of the home, particularly garden buildings such as the shed.

Our garden sheds protect a wide variety of belongings, from garden equipment and power tools to cherished mementos. That’s why it’s so vital to waterproof your shed from top to bottom, and make sure the inside is completely safe from any danger from the rain.

We’ve broken this guide on waterproofing sheds up into the main parts of a garden shed, from the base to the roof, so you can quickly use our table of contents below to find the information you need.

Table of Contents

How to Waterproof a Shed Base

The base of your shed can be the trickiest part to waterproof. This is because your ease of access to the shed floor can depend on how it was installed. Don’t fret however, as there’s still plenty you can do. It’s best to build your shed in a dry location that receives a lot of sunlight, and to build it so it isn’t in contact with the ground. One of the most effective ways to waterproof a shed base is to construct a substructure that will resist water ingress from below. If your shed has already been built, you could always retrofit a foundation underneath the existing structure.

When choosing the foundation for a garden shed, many choose either poured or block concrete. Concrete is a fantastically reliable building material which will provide your shed with a sturdy base for years. We’d also recommend adding some drainage around the base of your shed if at all possible. Options for this includes adding a gravel moat, or constructing a French drain, which is a drainpipe in a trench filled with gravel. Sealing the area between the foundation and shed base inside and out is another effective method of waterproofing, but this is harder after construction.

How Do I Waterproof Shed Walls

Waterproofing the walls of your shed is considerably easier than the floor, particularly post-construction. Walls often suffer from issues such as damp, mould, and leaks, so it’s always a good idea to maximise the water resistance of your shed walls. This is especially true for garden sheds that may be positioned against another structure or have valuables stored on or against the walls.

There are numerous ways to waterproof shed walls. The first is to treat the timber on the outside with a waterproof coating, which will not only help to seal it against leaks, but that fresh coat of paint will make your shed walls much more visually impressive. Do note that treatment is only effective at keeping water out of shed walls that are fully intact, with no cracks or other forms of damage, but treatment will still help to stave off damp.

Another method of waterproofing the walls of your garden shed is to add siding. “Siding” refers less to the walls themselves but more the “skin” presented on the outermost part of the structure. You have many materials to choose from when purchasing siding for shed walls. Vinyl for example, is a tough, highly waterproof form of siding that requires very little maintenance. Wood is perhaps the most common form of shed siding but requires sealing and treatment to be effectively water-resistant.

Waterproof paint is another option for homeowners looking to waterproof their shed walls. This form of paint has a similar effect to timber treatment, as it will make your shed much more resilient to the effects of bad weather or flooding. However, waterproof paint is often available in a much greater variety of colours, giving you much more creative freedom to choose the exact colour you want for your shed walls.

How to Waterproof a Shed Roof

Your shed roof naturally bears the brunt of water exposure, protecting it from all of the rain, sleet, snow, and anything else mother nature throws at us here in Britain. When you’re waterproofing a shed, giving the roof plenty of your time and attention is absolutely vital, and there are many things to consider. If you’re looking to purchase a new roof for your garden shed, you’ll need to consider cost, durability, longevity, and ease-of-installation along with its water resistance. It can be difficult when presented with so much choice, but our handy guide to the best shed roofing materials talks you through the pros and cons of each.

Some of the most popular roofing materials used on sheds include felt, shingles and lightweight metal sheets, all of which boast fantastic water resistance when first installed. However, these materials have very different lifespans and durability. For example, roofing felt is highly cost effective initially, but only lasts around 10 years and can be highly susceptible to leaks, tears and more. Metal roofing sheets, however, are incredibly strong and can last for over 25 years. So it’s important to consider future ongoing maintenance when choosing your new shed roof.

Aside from your choice of shed roof covering, perhaps the most important factor as to how waterproof your shed roof will be is correct installation. The substrate should be fitted properly and applied correctly, and the roof should also fit the inside of the shed just as well as the outside. If you’ve got quite a large garden shed, it may be worth considering adding a gutter to it. This will ensure that any rainwater can be transported safely away from the roof.

Waterproofing Shed Windows and Doors

Two elements not to forget are your shed’s doors and windows. These should be some of your top priorities when waterproofing a shed because they are some of the most common weak spots that rainwater and water vapour enter through. There are numerous ways to waterproof shed windows and doors, but it depends entirely on your garden shed’s construction. An old school, lightweight wooden shed is unlikely to be able to support the weight of double glazing for example.

No matter what kind of shed you have however, there are a few things you can do to waterproof the windows and doors effectively. It’s important to properly treat the door and window frames, particularly if they are made of wood. Proper and secure installation is also vital, as glazing that has not been sealed correctly or does not fit the window frame can be a prime target for water ingress. Ensuring that your shed door fits as snugly into the doorway as possible is also vital. This will prevent not only water ingress but cold air, damp, and moisture from getting in. Any gaps in your door frame should also be sealed up.

Other Ways to Waterproof a Shed

Shed Guttering and Drainage

There are plenty of options available for homeowners looking for guttering and drainage for their shed. Many traditional options such as cast iron guttering will likely be far too heavy, but thankfully there is a huge selection of lightweight UPVC guttering which is the perfect option for sheds.

Guttering will help to control any water that runs off of your roof. Without an effective guttering system, this rainwater will splash the walls of your shed as well as pool on the floor. This will of course lead to many problems such as damp build-up, mould, leaks and more.

Most guttering systems consist of a few guttering trays, which collect water from the roof and downpipes which transport it safely to the ground. From there, water is ejected into various systems such as water tanks, drains or soil deposits. The best guttering and drainage system for you depends on your situation. Water tanks for example are highly useful if you want to collect water for use on plants in your garden, but won’t be much use to less keen gardeners.

Improving Ventilation

Ventilation won’t be a feature that many British garden sheds have, but it’s definitely worth considering if you struggle with damp in your shed. Adequate ventilation allows moist air to escape, which will both help to avoid issues such as damp and mould as well as make the inside of your shed more comfortable. It’s quite easy to add ventilation to your shed, and many of the options are the same as for your house. Thankfully, improving ventilation for your shed is also quite straightforward, as many manufacturers provide easy-to-follow instructions with their products, so your shed could become well-ventilated in a matter of hours.

Avoiding Vegetation Growth

Although most of us will have sheds in our gardens, it’s actually rather important for you to avoid growing too many plants nearby. Plants require great quantities of water to survive, which means if your shed is nearby then it may suffer from damp as the flora draws moisture and groundwater towards itself.

If your garden shed is suffering from water-related problems such as damp, it may be a good idea for you to establish a “plant-free” perimeter around it if possible. Any flowers, shrubs or produce growing nearby should be moved to waterproof your shed and protect it more effectively against damp.

Adding Insulation

Insulation is a hugely important factor in waterproofing a shed. This is because effective insulation will help your shed to breathe, and excess moisture in the air will be removed. Insulating your garden shed will also make the interior of your shed far more comfortable, ideal if you want your shed to become a new living space. If you’d like to learn more about how to insulate a shed, be sure to read our handy guide.


And there you have it – a few simple, straightforward ways to protect waterproof a shed. You will find the best time to make these changes to your shed is in the warmer months, as most of these projects require dry weather in order to be successfully carried out. This will also mean you are fully prepared for winter and won’t find yourself out in the cold making last minute changes to your shed.

We have a wide range of different products on offer to help you get your shed waterproof – from treatments and mould removers to paints and insulation, you’re sure to find the perfect products to help you get your shed, and other garden buildings, fully prepared for the coming wetter seasons!

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