How To Prevent Your Shed From Rotting

Garden sheds are a quintessential feature of almost every garden you’ll come across in Britain. They’re great for storing tools, equipment, outdoor furniture as well as much, much more.

Typically made out of wood, garden sheds can range from the smallest of bike stores to massive backyard workshops. Wood is easy to cut, simple to use in construction, and looks great when sitting in your back garden.

But the fact that it is a natural resource means it has its dangers too. Taking proper care of a wooden shed is a must if you want them to last. Time and consideration must be put into ensuring the shed is clean, tidy and free of any potential dangers that may affect its longevity.

Wood rot is one of the most common problems shed owners face. Thankfully, there are ways you can prevent it from happening in the first place. That’s why we’ve written this article on the best ways to prevent your shed from rotting.

Let’s jump straight in.

What Is Rot?

Rotting and decaying wooden board
Image Credit

Perhaps the first thing to understand about wood rot is what it is.

Rot is the decomposition of organic matter. It refers to the process of decay, and it is caused by fungi. The fungi feeds on water and the wood itself, breaking down its structure. You can tell when it has rotted through the appearance of wood – it will appear soft and flaky.

Wood that has been damaged by rot is not easy to repair, so it’s imperative that you take steps to prevent it from happening in the first place, rather than waiting until it develops to act.

Identifying dry rot

There are a few different types of rot. They vary because of the different types of fungi that cause them.

If you’ve researched rot, you may have come across the term ‘dry rot’. Dry rot is colloquially known as brown rot, and it’s the most common variety.

It is very important to note, however, that dry rot isn’t dry. It is thought that the term ‘dry rot’ may have been coined due to the darkened appearance of rotting wood, and the fact that it is still visible when the wood is dry.

However, rotting can only occur in the presence of moisture. That means that even if your rotting wood is dry now, it would’ve been wet enough before for fungi to thrive and grow.

Interestingly, when timber is completely dry, rotting cannot take place. However, if your wood has been exposed to moisture at any time before, rotting can still take place. Other types of rot are less common and not worth mentioning. There are, however, many articles online explaining the different types of fungi if you’re interested.

What you do need to know is that as well as being the most common, dry rot is the most quickly spreading variety of rot – and therefore the most dangerous.

What Causes Rot?

Rainwater on a wooden board
Image Credit

Rot needs very specific conditions to occur. Unfortunately, here in Britain, our weather is the perfect storm for rot to culture in. The changing forecast, consistent rains, and temperate climate make it ideal for fungi to grow. Let’s take a closer look.


Fungi cannot grow in conditions that are too hot or too cold. Similar to humans, it thrives at temperatures between about 3 and 30 degrees celsius. If it’s too chilly, the fungi will become dormant; any hotter than 40 will kill it altogether.

This means that the height of summer and the depth of winter are the least favourable times of year for fungi and mould. But for most other parts of the year, fungi will be searching for the best environment to grow in. And they’ll want to do it as soon as they can.


Humidity is also a factor. This refers to how much moisture is trapped in the air. Rot thrives in conditions where humidity is over 20%. Generally, this is unavoidable in human life as our homes generally have humidity levels between 40 and 60%. However, for rot, the more humid it is, the better.

Why does rot affect wood then, you might ask, but not other materials?

A source of food

Simply put, fungi and bacteria feed on natural wood. As a natural product, it is a great source of energy for them and, along with moisture and the right temperature conditions, access to food is another key condition they require in order to survive and thrive.


Water condensation on a clear window
Image Credit

Water is the most important thing that fungi need in order for rotting to take place.

While water ingress causes natural wood to warp and bow out of shape, it can also lead to the growth of mould. This is because, like any living thing, fungi needs moisture to survive and, for them, the more water the better.

This is why you might see damp spots in your bathroom if you don’t open the windows or ventilate the room after a hot shower or bath. This happens because the water is hot enough to evaporate (turn to gas) and, when it is in a gaseous state, it can travel around the room quickly. It does this and reaches the walls where it condenses (turns back into a liquid) and settles.

Fungi can’t grow in the air, but they can on the walls. That’s why you should try and prevent water from settling on your timber walls as much as possible.

Similarly, in a wooden shed with no ventilation, moisture from the air (or from a water source, if you have one in your shed that has evaporated) will be trapped in. With no windows or way to get out, it will turn back into water droplets when it hits a solid surface and rest there, providing ideal conditions for the mould or fungi to reproduce.

While rot and mould growth are separate problems, they are similar in many ways. As this video shows, wood cannot rot without water. If you want to prevent rot, you need to get rid of water.

How To Prevent Your Shed From Rotting

Ecobase Fastfit Foundation Base
Ecobase Fastfit Foundation Base

[spacer height=”20px”]

1. Make sure you have a solid shed base

All types of wood and timber naturally absorbs water very easily. This means that if you were to install the shed with the floor touching the ground (i.e. damp soil), then water would begin to soak up through the floor.

As we mentioned already, water and wood is not a good combination, as it provides the right conditions for fungi to thrive and for rotting to occur.

To combat this, you need to make sure your shed is raised off the ground. People often use an impermeable material such as concrete, as it makes a strong sturdy base, to put the shed on.

However, you can use a treated wood base such as an EzeBase or a plastic base such as an EcoBase. Raising the building off the ground means that rainwater will not be able to soak up through the floor, or seep through gaps in the bottom of the shed if water collects on the garden after a storm or heavy rainfall.

2. Get your wooden shed pressure treated

At Garden Buildings Direct, we offer pressure treatment on many of our buildings specifically to help prevent rot and decay.

You can purchase pressure treatment for an extra fee on top of the price of your outdoor building, as it is not a procedure that can be done at home. Chemical preservatives are soaked into the boards in a vacuum-sealed tank filled with liquid. These chemicals help repel the growth of fungi and mould right into the core of the timber.

Alternatively, you can (and should) treat your wood annually at home if your building wasn’t pressure treated prior to you buying it. It won’t be as effective but is the next best thing if you don’t want to pay any extra at the point of purchase.

It also helps to treat the wood with a coat of wood preservative on top of the base coat. It is a very useful tool and will help the timber survive the elements and resist rot to an extent as well.

3.  Get some sunshine!

A sunny blue sky with scattered clouds
Image Credit

Make sure you put your shed in a place where the sun can easily access most of the walls. This will allow the heat from the sunshine to dry out the structure as quickly as possible after rainfall.

The quicker you can get rid of the moisture, the less time the fungi will have to grow. Placing your shed in a sunny location is also beneficial due to the possibility that, on a really hot day, any bacteria on the surface will be killed when the sunlight hits it. This way, you can make the weather work for you!

Avoid positioning your shed at the bottom of a slope as water could run down towards the shed and seep into the natural wood. As we’ve already discussed, water and timber is not a good combination!

4. Use water-repellent sealant

Water repellent sealant can be applied to wood, and is a great way to block water from potentially entering through any gaps. You should spray or paint on the sealant every 1-2 years to waterproof any gaps.

As you can tell, the main techniques for preventing rot revolve around preventing water getting to the wood. It really is that simple!

The Solution

BillyOh Heavy Duty Apex Windowless Log Cabin Store
BillyOh Apex Log Cabin Windowless Heavy Duty Shed

Thankfully, at Garden Buildings Direct, we offer a fantastic 10-year anti-rot guarantee on our buildings, so you don’t have to worry about any potential decay. For more information, please consult this article, or our terms and conditions.

Making sure you take care of your garden shed will ensure it lasts longer, and that you’ll be able to enjoy it summer upon summer without any problems. A garden shed can be extremely useful practically and can add life to your garden. So don’t lose your shed to rot!

If you’re interested in buying one of our rot-resistant timber garden sheds, take a look at what is on offer by using the button below!

Shop Garden Sheds

Disclaimer: Please note that this guide is intended to present general information regarding the subject. All information indicated are representative and not exhaustive, which means that the results may vary depending on your item, its size, complexity and other circumstances. This is only advice and we do not accept responsibility for any problems you may have whilst following this guide, it is only a representation and not a definitive guide. When in doubt, please ask your manufacturer before proceeding.