Metal sheds make a great room in the garden but can be freezing cold in the winter and too hot during the summer. Insulation can bring the temperature under control.
Most garden buildings we discuss are constructed from timber and there’s good reason. Wooden structures have always traditionally been used to create outbuildings in the garden. A timber shed range offers plenty of choice in terms of design and features.
However, metal sheds are available in increasing numbers and provide a good alternative to a standard garden shed. There are plenty of benefits to a metal construction, including durability and minimal maintenance required once the shed has been assembled.
A metal shed is also cost-effective, allowing the option to purchase a larger building within the same budget. The most common use is for storing garden tools and furniture, where the metal design provides an easy no-fuss solution.
If you plan on spending time inside a metal shed, such as for use as a workshop, controlling the temperature can be a challenge. As with any building, insulation is an option to reduce heat loss during the winter and get control over the atmosphere inside.
Can you insulate a metal shed?
It’s possible, yes, to insulate a metal shed. But it can be difficult & expensive compared to installing insulation in a timber garden building due to the design.
Unlike wood, metal conducts heat really well. This results in the temperature inside the shed being exposed to what’s going on outside. In the winter, any heat inside is quickly lost, making it difficult to maintain a temperature consistently higher than the surroundings. During the summer, heat from direct sunlight is conducted through the shed walls, creating stifling conditions inside.
The effect on temperature in a metal shed is often amplified due to airtightness and lack of ventilation.
Insulating a metal shed can be challenging, but a good idea if you plan on spending lots of time inside. The current structure should first be assessed to understand how the insulation will attach to the interior. A building with internal framing or battens creates cavities where insulation can be installed between.
Spray foam insulation is usually the best choice for a metal shed. While kits are available, spray foam is often installed by a professional and can be completed within a few hours. As metal sheds often suffer from condensation and trapped water, wool roll style insulation is best avoided as the moisture can lead to damp issues.
Insulating a metal shed with spray foam can be expensive. Wooden garden buildings can make a better solution to get greater control over the temperature inside. Timber sheds conduct less heat and the internal framing allows for other types of insulation to be installed.
How should I insulate a metal shed?
Once you’ve decided to insulate a metal shed, it’s time to decide which material to use. The structure should first be free of any leaks or similar issues such as damp.
Spray foam insulation – Polyurethane spray foam is usually the best choice for a metal shed. The application involves spaying the insulation against the walls and roof. The spray drys into a hard foam that covers all of the interior building surfaces. Spray foam creates airtightness so there’s nowhere for warm and cold air to touch, as well as providing excellent insulating properties.
Rigid foam boards – For most garden buildings, we always recommend using rigid foam board insulation. The use of insulation boards inside a metal shed will depend on whether the structure has any interior framing. The insulation board is cut and slotted tightly into place between the framing. As the boards are lightweight, they also make a great option for insulating the roof.
Guide: Metal vs wood shed – which is best?
Why insulate a metal shed?
There are plenty of benefits to insulating a metal shed. The cost can often be expensive in comparison to the building itself and it’s important to decide whether you use will get enough value out of having insulation installed.
Consistant interior temperature
If you are planning on spending lots of time inside the shed, insulation can provide greater control over the interior temperature. The effect of highly conductive metal walls and roofs results in large temperature fluctuations inside a metal shed.
Thin metal walls do little to maintain the temperature inside during the winter. If an electric heater is being used to warm the interior, it may require running consistently and heaters are very expensive. Heating a garden building should only be carried out in short bursts to make it cost-effective.
In the summer, the metal quickly heats up in direct sunlight, making the interior very warm and often unsuitable for spending time inside. In hot climates, the walls can also feel hot to touch when they have been sat absorbing sunlight for many hours.
Insulation is a great idea to reduce treat transfer through the walls and roof, allowing greater consistency over the interior temperature. With insulation installed, the heat cannot transfer efficiently from one side of the wall to the other, keeping heat locked inside during the winter.
The costs of insulation can be off-set with regular use of the building by requiring less use of an electric heater.
A common issue with metal sheds is condensation appearing on the roof and walls. Condensation occurs when moisture in the air turns back into liquid water.
As the temperature inside a metal shed increases during the day, warm moist air begins to rise. During the evening, the metal surface of the roof quickly cools. The ‘due point’ is reached and the moisture in the trapped air turns back into liquid on the metal surface.
Metal sheds are more prone to condensation compared with timber structures due to metal being a good conductor, quickly cooling when the temperature drops. As wood does not conduct heat as well, the surface temperature does not drop as quickly, avoiding condensation issues.
As well as improving ventilation, another way to reduce condensation is to prevent the surface temperature of the interior wall from cooling down as fast. Insulation applied to the walls and ceiling prevents them from efficiently conducting heat. The rate of temperature change is reduced and so is the amount of condensation that occurs.
Guide: Stop condensation in a metal shed
Sometimes the work we do inside a garden building can be noisy. For example, if the shed is being used as a workshop, power tools can often be heard by neighbours. At the same time, noise from outside can also be a problem if there are lots going on in the surroundings.
As well as insulating against heat, many insulation products also have an effect on acoustics as well. Therefore insulation can be used to dampen any sounds coming in or out of the metal shed.
Heat insulation products are often not designed with acoustic insulating properties in mind. The effects can vary between different types of insulation. Dense insulation products often work the best as they make it difficult for sound waves to travel through. Lightweight products such as rigid foam boards often don’t have much effect on the acoustics.
If acoustics are important when insulating a metal shed, be sure to find a product that has both thermal and sound insulating properties.
Overall, it is possible to insulate a metal shed, although it may not always be cost-effective. Metal is very conductive, making it difficult to control the temperature, compared with the surrounding weather conditions. The result is often freezing cold temperatures during the winter and condensation forming on the ceiling as the surface temperature drops in the evening.
Spray foam insulation will usually produce the best results in a metal shed. However, the application is often difficult and completed by a professional, which can be expensive.
A timber garden building makes a better option for insulating to spend time inside. The wooden structure conducts less heat and is easier to install insulation thanks to wooden internal framing.
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