Spending a lot of time in a shed during the winter months will require insulation. Even the cheapest ways of insulating a shed can reduce heat loss and create a comfortable atmosphere inside.
It’s increasingly common for sheds to be used as additional spaces in a rear garden. Some popular examples include as a small workshop or even a garden gym. The challenge with most sheds is being able to control the temperature and create a comfortable environment inside.
During the summer, a shed can be stiflingly hot when in direct sunlight, and in the winter the temperature can be freezing cold. This often results in a shed being thought of as unusable for anything more than storing garden equipment. With the correct insulation, a shed can be converted to a space that’s usable throughout the year.
Insulating a shed provides additional benefits than just better temperature control. If an electric heater is currently being used to warm up the shed, insulation can reduce the costs significantly. Without insulation, heat is quickly lost through the timber in the shed walls, which is not thick enough to retain much heat on its own. The initial cost of the insulation can be offset with the savings in electricity consumption over time as the shed is able to retain heat better.
Protecting delicate equipment is another reason to insulate a shed. Electrical equipment which can be damaged by freezing conditions is protected from the temperature getting too low when using insulation and a heater. When insulated correctly, a shed also experiences fewer issues with damp. Heat and insulation prevent moisture build-up that can lead to rot appearing in the shed walls during the winter.
Cheapest parts of a shed to insulate?
Heat loss can happen anywhere in a shed that faces the exterior including through the floor, walls and roof. Heat rises as the temperature warms up, causing a considerable amount of warmth to be lost through a shed roof. As walls are the biggest surface area, plenty of heat is also lost through the walls. The floor of a shed also contributes to heat loss, but not as much as the walls and roof.
When insulating a shed cheaply, we recommend focusing on the walls first as they make up the biggest space to prevent heat loss. The roof should also be an important priority but can be most costly when getting insulation into position. The floor is our last area to insulate, depending on the budget available. An uninsulated floor may feel cold, but a low-cost option can be to use an old rug or similar as an insulator. The windows can be responsible for twenty percent of the heat loss in a garden building and should be completely sealed to improve airtightness.
Cheapest & free ways to insulate a shed
Let’s take a look at some of the best options to insulate a shed cheaply.
One of the lowest cost and potentially free ways to insulate a shed is to use bubble wrap. The air pockets can slow down heat transfer between each side of the material, reducing heat loss and keeping a shed warm. As bubble wrap is both thin and light, it can often be very easy to get hold of from local hardware stores. Larger bubbles provide the best results for insulation.
An upgraded option is to use foil-backed bubble wrap. The additional foil coating on each side of the bubble wrap is designed to reflect heat and improve the insulating properties further. Foil-backed bubble wrap can be purchased specifically as shed insulation and provides great results.
Bubble wrap insulation is installed by being stapled into position on the interior framing of the shed. Be careful not to stable the exterior cladding as this can lead to a small gap for water to get through. Ideally, a small cavity should be left between the bubble wrap and cladding to allow air to ventilate and prevent damp building up. Once the bubble wrap has been installed, it can be boarded over with a low-cost wood such as OSB.
Bubble wrap is not recommended if the shed contains electricity and an alternative insulation material would be better suited.
Insulation roll comes in a number of different materials and can be suitable for use in a shed. Glass wool and mineral wool are two common options, with glass wool being the cheapest option. This type of insulation is commonly used in residential properties and is very effective at preventing heat transfer through walls and ceilings.
Due to the insulation roll being extremely thick, it also has good sound insulating properties. If the shed is being used as a small workshop, the sound insulation can prevent the noise from sounding as loud for those outside. A challenge with insulation roll is that as well as not being the cheapest option, it can also be different to work with.
To install an insulation roll inside a shed, it can be packed into the walls between the framing. The interior walls will then be boarded over with a low-cost wood board. Insulation roll products will have a fire safety rating, making them suitable for use in a shed when electricity is installed.
Polystyrene is the white material we often find in packages to prevent damage to fragile items. It can also make great insulation, despite being extremely lightweight. The cheapest option would be to use packaging polystyrene in the walls of a shed to improve insulation. While this would improve insulation, it could be a potential fire hazard if electrics are used inside.
Expanded polystyrene insulation (EPS) is a great choice for shed insulation. The manufacturing process of EPS creates a closed-cell structure that has low thermal conductivity. As well as being very lightweight, the material is also resistant to damp and won’t begin to rot away inside the walls of a shed.
Expanded polystyrene can be purchased as a large rigid board several metres in length. EPS is easy to work with and installation to a shed can be completed over a weekend. As it’s lightweight, it’s possible to place it in the roof without putting too much pressure on the structure of the shed. The board is cut down to size to fit tightly in between the framing of the shed, before being boarded over.
Rigid insulation board
The best type of insulation for any garden building is PIR insulation boards, but they are usually the most expensive option. The insulation boards are the same as those used in residential properties and have several benefits including being lightweight and easy to work with.
PIR insulation boards contain rigid foam on the inside and foil on each side of the board. Due to their high thermal values, less insulation is often required to achieve the same insulating properties. So a thinner board can often be used, great for sheds where the interior framing is not very thick.
Lots of different brands are available, with Celotex being the most popular. For a shed, we would recommend the lowest cost insulation board you can find. 25mm boards is a good balance between price and performance for insulating a shed on a budget. Thicker 50mm boards can also be used in areas of high heat loss such as the roof.
Insulation boards are installed the same way as EPS boards. Each piece of insulation is cut to fit tightly in between the shed framing. The foil on the outside acts as a vapour barrier to prevent water from getting stuck in the insulation, leading to damp between the walls. Once the insulation is in position, aluminium tape is used on the edges to improve airtightness and then the interior walls can be boarded over.
Guide: How to insulate a shed
Insulation to avoid
When exploring options for the cheapest way to insulate a shed, it can be tempting to use materials that are not suitable for insulation. One of the challenges with garden buildings, particularly old sheds, is that water penetration can lead to damp. Materials that are not waterproof can soak up water after heavy rainfall. When the water doesn’t dry out fast enough during the colder months, damp and potentially rot can occur in the shed and cause damage to the structure.
Cardboard – Sometimes cardboard is recommended to insulate a shed online. While it’s true, corrugated cardboard can slow down heat loss, the effects are not going to be impressive in a shed. The biggest challenge is that cardboard is porous and will take on water very quickly during the winter. This results in the cardboard beginning to break down and cause damp issues in the shed. With lots of cardboard inside, there’s a lot of water potentially trapped inside a shed.
Spray foam insulation – Foam insulation that is sprayed onto the walls does provide good thermal properties and is used in homes to improve insulation. However, it is very expensive, sometimes more than the cost of a shed, and so not suitable for garden buildings. There’s also no need for spray foam insulation as the interior wood framing of a shed provides the perfect cavity for traditional insulation such as boards to be positioned inside.
Wood boards – Using wooden boards to line the interior of a shed on their own is not enough to provide any substantial heat retention. While they are used in conjunction with insulation, the main reason is for aesthetic reasons to cover over the insulation in the wall cavity. Most wood board such as OSB or plywood is not thick enough to stop heat transfer so much as to keep a shed interior warm.
Even using some of the cheapest methods of insulating a shed can provide great results. Choosing the best insulation will depend on the budget and result required. When installing insulation, we recommend taking some additional steps to maximise the results that can be achieved.
Lining the interior wall
Once the insulation has been installed between the interior wood framing, it’s time to install the interior wall lining. Wooden boards can be used to cover up the insulation and improve the appearance of the interior. The boards are usually attached to the framing using nails or screws. Be careful not to use long nails that can go through the framing and into the cladding.
For a low-cost option, OSB board is best and provides good strength. Plywood and MDF can also be used but are usually more expensive. Once the interior wall lining it installed, it can be painted with shed paint.
Check for any leaks
Insulation works well, but the results can be reduced if the shed contains any gaps where water or cold air can get through. In an insulated shed, we aim to achieve airtightness to get the best results. Be sure to check common places such as the roof or in the corners of the shed for any gaps. Small holes can be filled using wood filler or sealant.
Inside the walls where insulation is installed can create the perfect environment for damp to form if there are any leaks letting rainwater into the shed. Check the floor for any parts of the shed that may be holding onto excess water. If the leak is coming from underneath, the shed floor may need repairing.
A common question is whether an insulated shed needs a vapour barrier installed. A vapour barrier sits on the warm side of the insulation to prevent water vapour in moist air from passing into the insulation. When warm humid air gets into insulation, it cools and the water remains as condensation, which can lead to damp. The vapour barrier prevents the air from getting into the insulation.
Some types of insulation such as PIR boards and foil-backed bubble wrap do not require a vapour barrier. The foil material on these acts as a vapour barrier and any gaps on the edges can be sealed with aluminium tape. If insulation roll is being used, a vapour barrier should be installed as well.
There are lots of cheap, or even free ways to insulate a shed. Installing insulation can allow the shed to be used throughout the colder months as a workshop or to store items sensitive to the temperature getting too cold. With enough insulation, constant heating is not required as the shed will be able to hold onto heat throughout the day.
The lowest cost option is bubble wrap, which can be stapled onto the shed framing and boarded over. Foil-backed bubble wrap insulation is ideal for sheds and provides better insulating properties. Many free options such as cardboard can potentially lead to issues including damp and have little effect as insulation.