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  • Jeremy Horning

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

Updated: Dec 15, 2022

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

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

Why Are Moisture And Condensation in a Shed Bad?

Garden sheds should not be exposed to excessive moisture as it can result in a condensation problem. So it is essential to know how to stop condensation in a shed.

How does condensation happen? When the outside air is cold, and there is warm air inside a metal shed - the air will reach its dew point - the moisture content (water vapor) turns into liquid. Because of the fact that hot air rises, the shed roof is the moistest area.

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

  • Moisture spots forming on shed walls and ceilings

  • Insulation deterioration

  • Paint peeling

  • Window frames rotting

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

Note that some respiratory issues are linked to spending time in moldy areas. These issues include:

  • Pneumonia

  • Asthma

  • Bronchitis

  • Sinusitis

This is why you must prevent moisture from building up and keep your shed properly maintained all year round.

Which Are The Main Entry Points Of Moisture?

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

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

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

  • Shed walls: If your shed is not sealed adequately, moisture can get in through the walls.

  • Panels: This might be surprising, but moisture can also get inside your shed via the side or end panels if there happens to be vegetation touching them.

Our Tips to Help You Control Humidity And Dampness And Mold-proof Your Shed

Protecting your shed's interior perimeter is vital to avoid condensation problems and prevent mold or mildew from growing.

The following are the best steps for controlling humidity in a shed and to prevent moisture problems, regardless of the weather conditions.

Insulate Your Shed's Interior Perimeter

Insulation is 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.

You can get insulation products to act as a vapor barrier with 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 potential entry points for moisture. 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

We recommend using a dehumidifier, especially if storing semi-perishable items, electronic equipment, and other moisture-sensitive items in your shed. While this method might seem a bit extreme, it is worth every penny you spend if your items are of value. An electric dehumidifier works well, but you will need electricity. And it is only effective if your shed does not experience frequent temperature drops below 21 degrees.

Use a Window Fan Or Air Conditioner To Improve Air Circulation

You can use an air conditioner or window fan whether your wood/metal shed has vents or not but do not use both of them simultaneously.

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

Use Containers Of Calcium Chloride

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

Use A Concrete Vapor Barrier

A vapor barrier is a sheet of black plastic positioned beneath the concrete base of a shed. What does a concrete vapor barrier do? It acts as a blockade between the shed floor and the soil. With this, moisture can't seep through the concrete slab and make its way into the shed.

Install a Proper Ventilation System

Proper air circulation stops moisture from building up in a 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 the shed roof. The roof and gable vents protect your shed by allowing hot air to escape but not allowing melted snow or rain to enter. Check our guide on shed ventilation ideas for more inspiration.

Leave Some Open Space Between Different Items In The Shed

Spacing is important when it comes to stopping condensation in metal sheds. Aim to leave at least 10 cm of space between cool surfaces like walls and objects stored inside the shed. Better spacing and air circulation will help to stop condensation.

Apply Caulk To The Outside Of Your Shed

A tight waterproof 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, windows, and anywhere siding sections join.

Let in Fresh Air

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

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 the 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 moisture-free.

Understand Different Foundations And How They Absorb And Distribute Moisture

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

Are you looking for a more solid foundation or building a bigger shed? Then consider having a concrete foundation installed.

Buy Quality Storage Containers to Properly Organize Different Types of Items

Organizing the various items in your shed will help prevent condensation and moisture buildup.

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

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

Remove Excess Vegetation

As we stated before, moisture can creep into your shed through the panels if vegetation is in contact with them. Try as much as possible not to place metal sheds close to shrubs and trees. During the night, these shrubs and trees let off moisture, which could pass through your shed's ventilation panels, moistening the air in your shed, and causing condensation.

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 you don't go for cheap materials or a cheap foundation if you plan on building a new shed.

Ensuring you contact a professional with the experience it takes to build great sheds is the best way to get premium results. There are many benefits to getting sheds from Urban Sheds as they have the best professionals and their range of sheds is of the highest quality.


When water vapor comes in contact with any cold surface in a garden shed (wooden or metal), the air condenses and forms water droplets. There are many ways to stop condensation from escalating in your shed. Try promoting cool air circulation with air vents or windows and installing better insulation.

Take all the preventative measures listed here, and you won't have to worry about moisture problems in your metal shed.


1. Why is my shed damp inside?

It is common for a garden shed to be damp. This is an issue that arises as shed condensation forms. When surfaces such as metal walls 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 poor air flow, lack of insulation, or shed roof damage.

2. Why is mold growing in my shed?

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

3. Why is my shed roof wet inside?

A condensation problem might arise if your backyard shed has a wet roof. Condensation occurs when warm air rises and meets the cold plastic or metal shed roof.

4. What kills black mold instantly?

There are various efficient ways to kill black mold in garden sheds. The best methods include cleaning with 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 grows on warm or moist surfaces. It also has a powdery or fluffy texture. Mold, on the other hand, typically grows beneath wet surfaces. It has a slimy or fuzzy texture and is usually black or green.

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