• Jeremy Horning

How to Stop Condensation & Moisture In a Shed - 15-Step Solution to Prevent Growth of Mold and Milde

Updated: Nov 17

If you have a shed, then you should know that it can be quite annoying to face moisture problems. Excess and uncontrolled interior moisture can damage the fabric of your backyard shed and also destroy your metal tools and other equipment.

In this article, we will be looking at everything you need to know to keep your garden or steel shed dry and free of dampness.

Why are moisture and condensation in a shed bad?

Your garden sheds or metal sheds should not be exposed to even the slightest condensation problem.

How does condensation happen? When the outside air is cold, and the air inside is warm, the metal shed could reach a dew point. At this point, the air needs to be cooled, which would turn water vapor into liquid. Because of the fact that hot air rises, the roof is the area that is most moist.

When there is too much moist air in your shed, it can lead to:

  • moisture spots forming on walls and ceilings

  • Insulation deterioration

  • Paint peeling

  • Window frames rotting.

If you don't stop moisture from building up, it can lead to some costly damage like the growth of mold.

You should keep in mind that there are some respiratory issues that are linked with living in moldy areas. These issues include:

  • Pneumonia

  • Asthma

  • Bronchitis

  • Sinusitis

This is why it is highly imperative to prevent moisture buildup and keep your shed properly maintained all year round.

Which are the main entry points of moisture?

So what are those parts of your shed that absorb moisture first? There are different entry points, including the walls and shed base.

  • Shed roof: The shed roof is the moistest, thereby making it one of the main entry points of moisture.

  • Shed base: If your shed is constructed directly on the ground, then water could seep up through the areas of contact into the frame and walls.

  • Shed walls: Also, if your shed is not properly completed, then moisture can get in through the walls.

  • Panels: This might be surprising but moisture can also get inside your shed via the panels if there happens to be growing vegetation touching it.

Our tips to help you control humidity and dampness and mold-proof your shed

Protecting your shed's interior perimeter is highly important if you want to avoid condensation problems and also prevent the growth of mold or mildew.

These are the best steps to follow to prevent moisture problems in your shed, regardless of the weather conditions.


Insulation is practically the best way to tackle condensation problems. It prevents the issue by raising the surface temperature, which in turn also makes your garden shed more efficient as it reduces heat loss and gains.

You can get insulation products to act as a vapor barrier because they have a reflective foil surface and a closed-cell foam structure.

Find and seal any leaks in your shed

It seems obvious, but any leaks in metal sheds are entry points for moisture to get in. So, inspect your shed thoroughly and check if there are any cracks or leaks, especially in the roof joints. Also, pay attention to the shed base and any area with water pipes.

Install a Shed Dehumidifier

Using a dehumidifier is highly imperative, especially if you are storing semi-perishable items, electronic equipment, and other useful records. While this method might seem a bit extreme, it is worth every penny you spend, particularly if your items are of so much value. An electric dehumidifier works great, but you will need electricity and temperature drops below 21 degrees are not allowed.

Use a window fan or air conditioner to improve air circulation

You can utilize an air conditioner or window fan if your shed has vents or not. But, you should keep in mind that you are not to use both of them simultaneously.

A window fan helps improve the circulation of air in and out of your shed. It lets in fresh air and vents out hot air. Operating a window fan is great for battling condensation. You can easily control humidity by running the fan during the day or when you need to.

Place Containers of Calcium Chloride

Calcium chloride draws humidity and moisture from the air, so it will be ideal to place containers filled with calcium chloride in your shed. You can check the package of the calcium chloride to know how many of the containers you will be needing for your shed.

Use A Concrete Vapor Barrier

A vapor barrier is a sheet of black plastic that is positioned beneath the concrete base of the shed. What concrete vapor barrier does is it acts as a blockade between your shed and the soil. With this, moisture would not be able to creep up through the concrete slab and make its way to your shed.

Install a proper ventilation system

You need proper air circulation if you want to stop the build-up of moisture in your metal shed. There are different ways you can improve the ventilation system. You can install vents on opposite walls for maximum ventilation.

Try installing gable vents in the shed's gables and a ridge vent in your shed roof. These vents protect your shed by allowing hot air to escape but do not let melted snow or rain get in. Check our guide, If you need some inspiration for shed ventilation ideas.

Leave some open space between different items and objects in the shed

Spacing is very important when it comes to stopping condensation in metal sheds. You should aim to leave at least 10 cm of space between the wall and objects, and even cool surfaces. The better your spacing and air circulation, the more you have a chance to stop condensation.

Apply caulk on the outside of your shed

Creating a tight seal is a great way to deal with condensation in metal sheds. While you can improve air flow with ventilation, you can apply caulk at the base of your shed to handle moisture. Caulk prevents rain from getting into the shed. It also ensures that water doesn't seep into your shed from the ground level.

The caulk should be applied around corners, air vents, doors, and windows, basically where siding sections join.

Let in Fresh Air

You can make use of open shelves to allow fresh air circulate and freshen all the stuff and equipment you keep in your shed. Air should be constantly flowing around all the objects in your building, so be sure to leave some space around them. If you also want better air circulation, ensure you leave a gap between the shed and the wall.

Put desiccants in strategic places

Placing desiccants in places that are prone to condensation helps battle the problem. A desiccant is a material that draws out moisture from the atmosphere. A good example would be that tiny pack of silica gel placed in new shoe boxes or a pack of vitamins. These materials are very efficient in keeping the environment dry and free from moisture.

Understand different foundations and how they absorb and distribute moisture

There are various types of shed foundations, and how they relate to moisture differs. You can build a plastic foundation to have an environmentally-friendly base for your shed.

If you are looking for a more solid foundation or you are building a larger shed, then you should consider having a concrete foundation installed.

Buy quality storage containers and properly organize different types of items

Organizing the different items in your shed accordingly will help you prevent condensation and moisture buildup.

A scattered and packed shed will not just lead to the deterioration of the equipment and items but will also make the shed more susceptible to condensation.

So, ensure you buy high-quality storage containers and store each item in the right places.

Remove excess vegetation

Just as we stated before, moisture can creep into your shed through the panels if there is vegetation coming in contact with them. Try as much as possible not to place your metal sheds close to shrubs and trees. During the night time, these shrubs and trees let off moisture and it could pass through your shed's ventilation panels and then condensation would occur.

Have your shed properly built

If you want your shed to withstand moisture, then you need to have it built to the best standard. Ensure that you don't go for cheap materials or a cheap foundation if you are looking to build a new shed.

Ensuring you contact a professional that has what it takes to build a great shed is the best way to get premium results. There are lots of benefits to getting your sheds from Urban Sheds as they have the best professionals and their sheds are of the highest quality.


When water vapour comes in contact with any cold surface in your metal or garden shed, the air condenses and forms water droplets. There are a lot of ways you can stop condensation from escalating in your shed like promoting cool air with the use of air vents or getting better insulation.

Taking all the prevention methods listed here means that you won't have to worry about moisture problems in your metal shed.


1. Why is my shed damp inside?

It can be quite common for your garden shed to be damp. This is an issue that arises as shed condensation forms. When surfaces such as metal and glass windows in your shed get cold, the moist air gets stagnant and mildew might form. A damp atmosphere in your shed could also be due to bad air flow or the shed's roof damage.

2. Why is mold growing in my shed?

If your garden or metal shed is not getting the air circulation it needs and only absorbing moisture, you might notice mildew growing. This is because constant moisture is the perfect breeding ground for mold to develop in the shed.

3. Why is my shed roof wet inside?

You might be faced with condensation problems and this is a major culprit for having a wet roof in your backyard shed. When the warm air rises and meets the plastic or cold metal shed, condensation occurs.

4. What kills black mold instantly?

There are a lot of efficient ways you can kill black mold if you happen to find it in garden sheds. Some of the best methods to try out include using lemon juice, distilled vinegar, baking soda, and hydrogen peroxide.

5. What is the difference between mold and mildew?

Mildew is usually yellow, gray, or white and they grow on surfaces that are warm or moist. They also have a powdery or fluffy texture. Mold on the other hand typically grows beneath surfaces of things that have gotten wet. They have a slimy or fuzzy texture and are usually black or green.

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