Shed Ventilation Explained: A Thorough Guide


Are you looking to understand shed ventilation and what options there are? In this guide we’ll look at how to ventilate your shed, what are the signs that you need better ventilation, plus what choices are available. You’ll also find tips on how to reduce the moisture level so that your garden shed stays in great shape for years to come.

Table of contents:
Do sheds need ventilation?
What happens if my shed has poor ventilation?
Does a shed need ventilation underneath?
Does a shed roof need ventilation?
How to get rid of excess moisture in your shed
Garden shed ventilation options

Do Sheds Need Ventilation?

Yes, all buildings need a healthy airflow, including garden sheds. Whether it’s made of wood, metal or plastic, having proper airflow is key to preventing moisture and heat build-up. And, if you keep any chemicals or other combustible liquids in your shed, good ventilation is important to avoid fumes in the shed.

So, how do you ventilate a shed? Just open a door or a window. That’s it! For most sheds this will do the trick. 

But, if you’ve noticed signs of poor air quality or too much moisture, you may need to add additional ventilation. This depends on the root cause of the problem. Moisture problems for example can also come from a lack of damp proofing.

You should also be aware of the chance in seasons. In the winter you can heat up your garden shed every now and then to get ride of excess moisture or use any of the other tips we’ve laid out further down.


What Happens If My Shed Has Poor Ventilation?

A few things can happen when you don’t have enough moving air in your shed:

  • Heat damage: During hot summer days sheds can heat up quite a bit, especially metal or plastic ones. This means that the items stored in it may get damaged. While metal sheds do cool down fast in the evenings, they get very hot during the day. Wooden garden sheds are typically the best for temperature regulation. 
  • Chemical fumes: Fumes from gasoline, fertilizer, pool chemicals, etc. can damage your health. You don’t want to inhale these fumes or let your skin get irritated by them.
  • Moisture damage: Moisture can damage the shed itself as well as anything you store in it. Most materials take damage from too much water exposure. 
condensation on window

How Do I Know if My Shed Needs Additional Ventilation?

There are different signs you can pay attention to:

  • Condensation: Check for condensation on the inside walls, ceiling or stored items.
  • Musty or damp odour: A persistent musty or damp smell inside your shed is often a sign of high humidity levels. The odor is caused by mold, mildew, or decaying organic materials.
  • Warped wood: If your shed is made out of wood look out for the walls or floor warping or swelling. This is a sign of the wood absorbing too much moisture.
  • Mold or mildew growth: Mold or mildew growth on the interior surfaces, stored items, or on the shed’s structure, is a clear sign that there is a moisture problem.
  • Peeling paint or wood rot: Excess moisture or ventilation problems cause paint to peel or bubble and wood to rot or decay.
  • Rust or corrosion:  Are you seeing any metal parts of the shed or stored tools showing signs of rust or corrosion?
  • The humidity level is above 60%: Use a hygrometer (a device that measures humidity levels) to monitor the shed’s interior. If the humidity consistently exceeds 60%, additional ventilation is likely needed.
Garden shed Eva F by Martin

In the photo above: Garden Shed Eva F

Does a Shed Need Ventilation Underneath?

This depends on the type of base you’ve chosen for your shed, but in general, the answer is yes. If you don’t have a healthy air flow below the floor, moisture can start to build up there. Given enough time, it starts to cause damage. If you have a wooden floor this means rotting wood, there can be mould growth and even pest infestations.

To avoid issues you can elevate your shed off the ground using blocks, screw piles or a cost-effective LogFoot foundation.

If you have a concrete base, it’s important to damp-proof your foundation.

Does a Shed Roof Need Ventilation?

This depends on your situation and whether the building already has some kind of ventilation. If there are no signs of the issues we’ve covered above, your shed is likely fine. 

Does an Insulated Shed Need Ventilation?

An insulated garden shed needs to be ventilated like any other type of shed. If you’re opening doors and windows regularly, that is enough. But if you plan to not use it for a while consider using a dehumidifier or adding additional ventilation.

Before we move on to different types of natural ventilation and mechanical ventilation you could use, let’s look at a few helpful tips to control humidity in a shed.

How to Get Rid of Excess Moisture in Your Shed?

Cut back any plants touching your shed: Moisture transfers from plants to buildings. Protect your shed by removing or cutting back any plants around it.

Raise the shed: If you haven’t left space between the ground and your shed, it’s important to stop the moisture seeping in through the floor.

Leave space between the wall and the items you store: About 2-4 inches is enough. 

Improve Drainage: Ensure proper drainage around the shed by sloping the ground away from the shed and installing gutters to direct water away from the structure.

Use silica gel, kitty litter, charcoal briquettes or calcium chloride: All of these work to absorb excess moisture. Make sure to consider safety and placement if you have kids or pets going into the shed. If you’re worried about tools getting rusty, you can sink them in kitty litter and also put containers with kitty litter around them.

Use a dehumidifier: A dehumidifier can effectively remove excess moisture from the air inside the shed. Choose a model with the appropriate capacity for the shed’s size and run it as needed.

Heat up the shed: During colder weather, you can use a heater every once in a while. Hot air moves toward the cold and takes humidity with it. Make sure there is an opening through where the air can escape.

Garden Shed Ventilation Options

Adding additional ventilation to a new or existing shed is relatively easy. With a smaller garden structure you just need two vent openings on opposite sides of the shed so that the air can be pulled through.

If you’re putting up a new shed the best thing is to position it according to the wind direction. First determine where the prevailing wind direction is from. Then, if possible, make sure the gable end of your shed is in the way of the airstream.

1. Gable Ventilation

Adding small ventilation grilles to the gable ends is a great way of increasing airflow. Pick out the type of small grilles that match your summer house. You’ll also want to make sure the vents have a mesh or net that stops insects from coming in. 

2. Rooflight Vent

These are a great option if you’re also looking to add a light source to your shed. A ventilation rooflight is installed on the roof and has a transparent cover made of strong plastic.

3. Roof Windows

If your shed happens to be bigger and you use it as a workshop or even a gym, this might be one of the best options for you. With a roof window you’ll have a lot of extra light and an additional big opening

4. Whirligig

A whirlibird or whirligig is great for larger sheds. This turbine vent is shaped like a dome is usually installed near the apex of a roof. It spins around when wind blows and pulls out hot air from the shed. Whirligig vents work best when combined with other vents – like a passive vent on the wall. This is because for air to be able to move effectively it has to have an entry point and an exit point.

5. Electric Fan

Install a small electric fan on the window or the wall to move out the air. You can also use solar powered fans to cut down on the cost of electricity.

If you have a larger space you need to ventilate, you can read our summer house ventilation guide here.


In most cases your shed will do just fine with passive ventilation. Especially with wooden sheds additional ventilation isn’t often needed. That’s because due to the material and the construction of the building, there are enough gaps to allow for air to move naturally. By keeping an eye out for any possible issues and dealing with them swiftly, you’ll keep your garden shed in great condition.