All buildings use some form of ventilation and garden buildings are no exception. Installing vents in a shed can provide fresh air inside and maximise the lifetime of the structure.
Garden sheds have become far more than just a place to store a lawnmower and outdoor furniture during the winter. Plenty of sheds are being used to keep valuable items inside such as bikes or used as an extension of a utility room. Large sheds can also be used as a workshop or garden office during the warmer months.
While garden buildings are great, they do take some careful consideration and maintenance to keep them protected against the elements. One of the biggest challenges is the cold and damp weather in the winter that can eventually result in rot to the wood.
Ventilation is an important step in maintaining a shed and provides benefits in both the summer and winter months. Larger outbuildings typically come with vents pre-installed, but sheds are often not included. Luckily, improving ventilation in a shed is easy and can be completed even if the building is already several years old.
Does my shed need ventilation?
In short, yes, all sheds should have some form of ventilation in the structure. The exact type and amount of ventilation needed will depend on the size of the building and how it is being used.
Small sheds used for storage may be fine without any additional vents due to the lack of airtightness in single-skinned timber buildings. Larger sheds or those converted into a space where people will spend time inside may need an additional ventilation system fitted. Even a small passive air vent can make a noticeable difference to the air quality inside and prevent damp issues from occurring.
Why does my shed need ventilation
The main reason to ventilate a shed is to prevent the build-up of damp and moist air during the winter months. Moisture can get into a shed from storing damp furniture inside or even through small gaps in the walls & roof if the building is not treated correctly.
Sheds where the interior has been lined and insulated to spend an extended period of time inside can increase the potential build-up of moisture. The insulation will improve the airtightness of the building, reducing any natural ventilation and leaving damp air with nowhere to go.
During the summer months, when a shed is positioned in direct sunlight and has a dark coloured felt roof, the temperature inside can become sweltering quickly. Ventilation can let the warmer air escape and reduce the effect of the sun on the interior temperature.
How does shed ventilation work
An outbuilding with poor ventilation is easy to identify. In the winter, mould growth can begin to form on items made from organic matter such as garden furniture. If the walls are also damp, mould can grow on the timber and eventually lead to rot if left untreated. Another common sign is condensation forming around the windows or roof as the trapped water vapour in the air begins to cool.
Ventilation inside a shed works by replacing the trapped moist air with fresh dry air. This avoids creating a scenario where dampness and condensation are allowed to form. Ventilation is continuous and a constant cycle of allowing fresh air to flow into the building and stale air to escape.
Different types of ventilation
Ventilation systems come in lots of different forms, depending on the construction of the shed and how it is being used. Timber buildings typically do not have a high level of airtightness, allowing the structure to ventilate naturally when only small levels of ventilation are needed, such as storing items inside.
Passive ventilation uses natural forces such as the wind to circulate air into the shed. Examples include air vents on the walls or leaving the windows open. The air inside is regulated as fresh air is naturally pulled in and stale air expelled.
Best results with passive ventilation systems are achieved by placing a vent at opposite sides of the outbuilding. One vent is placed low down the wall and the second is placed higher up on the opposite wall. This creates a natural tunnel for the air to flow through, coming in on one side and being expelled on the other.
As passive air vents are reliant on external conditions, sometimes they need some help and this is where active ventilation comes in. Active vents use electricity to help the air along, with systems such as a fan. With electrical assistance, we can provide higher throughput of fresh air at any time of the day. An active vent system may be used if the shed is functioning as a workshop or similar.
How should I ventilate my shed?
The exact method to ventilate your shed will depend on the size and how the building is being used. For most sheds, passive vents will provide adequate ventilation without the need for an additional active system.
Open the windows and doors
A simple way to improve ventilation is to open the windows and doors. Many sheds will remain closed for months over the winter, preventing air from circulating. If you don’t want to install an extra ventilation system, first try leaving the windows and doors open regularly.
An hour each day should be plenty of time for the shed to ventilate properly and ensure there is an adequate supply of fresh air. Shed windows that open are ideal as they can be left partially open throughout the day. The open windows can also keep the shed cool during the summer by allowing the hot air to escape.
Install a passive vent
A passive air vent is easy to install and can make a big difference to the air quality inside a shed. We recommend installing two vents for the best results, but even a single vent will make a noticeable difference.
The passive vent will allow air to naturally pass through and enter the shed, circulating around and allowing stale air to escape. the single event is positioned near ground level to allow cool air to enter. A double vent system places a secondary vent higher up on the opposite side. This allows air to enter near the bottom and exit near the top as it becomes warmer.
To install the vent, a section of the timber needs to be cut out. We recommend placing screening inside the vent to prevent insects from getting inside the shed. Passive vents are a low-cost option that provides effective results.
Use an electric fan
When a shed has been converted and is being used as a workshop, garden gym or similar, additional ventilation is often required. Humans spending a long time in a small space can lead to poor air quality if there is not much ventilation.
Thankfully, most of these use cases already require electricity to be installed and so using an active fan ventilation system is a great idea. The fan can provide consistent airflow into the shed, which isn’t dependent on the weather conditions outside. The fan is installed similar to a traditional vent by removing a section of the wall where the fan will be fitted.
Guide: How to stop condensation in a metal shed
Additional steps when ventilating a shed
Installing ventilation into a shed improves the air quality and protects the interior against damp and mould growth. Additional steps can be taken to protect the outbuilding further against moisture and rot to timber.
Apply a wood preserver
As well as improving the appearance, a wood treatment such as a preserver provides long term protection to the timber. While it’s common to apply a preserver to the exterior, it can also be applied inside the shed to protect against mould growth.
Once the wood preserver is dry, it creates a waterproof layer on top of the wood to stop moisture from getting inside. This can be seen by beading as water touches the surface. Making sure the preserver on the exterior is still waterproof is also important to avoid moisture passing through into the shed after heavy rain.
Install insulation
Mould growth is commonly found where conditions are cold and damp, which is a typical shed during the winter. Installing insulation helps to maintain a consistent temperature inside the shed, and avoid the conditions getting too cold or damp. Warming the interior, by using an electric heater can avoid damage to the contents inside and prevent damp.
There’s a lot of ways to insulate a garden building and the easiest is using rigid foam insulation boards. The insulation can be installed between the framing of the shed and then boarded over with wood such as OSB. A small heater can then be placed inside of the shed is being used during the winter months. A passive vent will also be needed for fresh air to enter the outbuilding.
Summary
All buildings need ventilation and a shed is no exception. If the shed is just being used for storage, the natural ventilation of a timber building may be fine without the need for any additional vents. But if you begin to notice mould growth or condensation, it’s time to consider installing extra ventilation.
We recommend installing a passive air vent to allow air to circulate around the interior and replace any stale air inside. If the shed has been converted into a workshop and you are going to be spending a lot of time inside, consider an active vent instead.
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