Insulate Garden House: Guide

Last updated on October 23rd, 2023 at 09:04 pm

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Careful insulation of your garden house is the be-all and end-all – not only if you use the little house as a lounge and hobby room all year round. After all, professional and comprehensive insulation keeps moisture and mold out, reduces energy consumption and saves you money. We explain which materials are suitable for insulation, how you can proceed step by step and what mistakes to avoid.

Advantages of garden shed insulation – when does it make sense?
The most important thing right at the beginning: we recommend insulating even garden sheds that are only used for storing gardening utensils, furniture and tools. Do you use your garden house as a hobby room, to overwinter your plants or to sit together with friends? Then the garden shed should be insulated in any case.

Insulate Garden House: Guide

Careful and professional insulation of your garden shed has great advantages: On the one hand, the insulation keeps the heat in the garden house, while at the same time keeping the cold and moisture out. In this way, the garden house is protected in the long term from frost and cold damage, mold and rust caused by the weather. Especially if you use your summerhouse as a year-round living space and heat it, good insulation saves a lot of heating costs.

However, if you decide not to insulate, it is always advisable to install a room dehumidifier or dehumidifier to keep moisture and cold from getting to the items in the garden shed.

How to insulate the garden house?
A garden shed can be insulated both from the inside and from the outside. It also makes sense to insulate the roof and floor (see instructions for multi-layer insulation system ). As a rule of thumb, however, the more thoroughly you insulate, the better for the subsequent heat balance and climate of the summerhouse. We have summarized all the important steps for you below.

Select the right material

The first step in insulating is the selection of insulation materials. The following materials are suitable for interior or exterior insulation of the garden house and are most often used:

Mineral wool, wood wool, hemp fiber:
Insulation boards or mats made of these materials are insensitive to moisture and do not mold. Be sure to wear gloves, face mask and long clothing when processing to prevent irritation of mucous membranes and inhalation of the fibers.

Cost: 5 – 15 euros per m²

The so-called perlite fill consists of silicone-coated, water-repellent beads that are poured into the insulation space. Perlite is also available as a board in specialist stores and offers an extremely high insulating value.

Cost: approx. 15 euros for 100 l of perlite; 35 euros for a 2 m² slab.

Hard foam boards:
Panels made of Styrodur (XPS) are easy to cut and process – ideal for beginners. In addition, the material is weather-resistant, pressure-resistant and insensitive to moisture.

Costs: approx. 50-60 euros for 10 m².

Styrofoam boards:
Styrofoam boards (EPS) are more coarse-pored and therefore difficult to cut and process, but are equally suitable for insulating a garden shed.

Once the appropriate material has been selected, it’s time to prepare for the next steps. First, check that you have all the tools and supplies you need. You will need:

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Saw to cut the floor boards & wooden panels for boarding up.
Knife to cut the insulation
Stapler for fastening the diffusion-open foil
Brush or roller to apply the wood preservative paint
Cordless screwdriver for fastening the floor boards
chipboard screws
Protective clothing (mouth guard, safety goggles, gloves, long clothing)
Once all the preparations have been made, it’s time for the actual insulation work.

Instructions multi-layer insulation system
Basically, you do not have to insulate the entire summer house, you can of course insulate only individual walls or only the floor. However, we recommend in any case the so-called multi-layer insulation system, a circumferential insulation of the interior or exterior walls. This involves insulating the walls, roof and, above all, the floor. After all, it is through the floor that most of the cold enters the summer house. This is where the greatest potential for insulation exists in order to save energy, protect objects from moisture and keep the heat in the summer house as well as possible.

Tips for installing insulation of four main areas.
Most often, the floor in the garden house consists of a simple floor slab made of concrete or cement. This is where most heat is lost and cold enters the garden house. Therefore, the floor should be insulated especially thoroughly.

It is important that the insulation does not have direct contact with the ground, but allows air circulation. Therefore, to insulate the floor, a special film, called a diffusion-open insulation film, is first applied to the floor. This prevents the insulation from drawing moisture. Alternatively, you can use carpet here. The foundation of floor boards is then laid on top of the special foil.

These planks should be as thick as the insulation material. Ideally, the wooden planks are also treated with wood preservative paint to provide additional protection against moisture. Now lay the insulation cut to size in the gaps between the foundation planks. You can seal the joints between the insulation material and the floor boards with silicone for additional protection against moisture and cold. This is followed by another layer of the special foil.

Finally, the construction is boarded with floor boards. However, a gap should be left between the insulation material and the boarding to allow natural air circulation and to protect the insulation material from moisture and thus mold.

The roof of your garden shed should also be carefully insulated, because according to experts, up to 40% of the heat is lost here. When it comes to roof insulation, a distinction is made primarily between above-rafter insulation installed from the outside and between between-rafter and below-rafter insulation installed on the inside.

The above-rafter insulation is applied to the roof from the outside. However, if the roof is to be insulated afterwards, it must be unroofed and reroofed with this type of insulation. Ideally, therefore, this type of insulation is installed directly with the construction of the garden house. Compared with a subsequent insulation of the roof, you save yourself a lot of work. The procedure here is similar to the steps of floor insulation.

First, apply the special film and attach the wooden planks treated with wood preservative paint. Make sure that these planks are as wide as the thickness of the insulation or minimally larger. Now cut the insulation to size and clamp the blanks in the gaps. Our tip for insulation with mineral or wood wool: cut the insulation about 3% larger than the distance between the wooden planks. This way, you can simply press the insulation into the gaps, where it will reliably hold. On top of the insulation, you again apply the special foil as a vapor barrier. Finally, you board up again. In the last step, the boarding is followed by roof shingles or roofing felt.

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The principle is the same for between-rafter and under-rafter insulation. Here, however, the insulation is installed from the inside: Fasten the insulation material between the roof beams or clamp the insulation wool in place. This is followed by the special foil as a vapor barrier and the sheathing with wooden panels.

You can insulate both the interior and exterior walls. Optimal would be even insulation of both walls, because: The tighter the insulation, the better your garden shed will be protected.

Insulation of the interior walls also follows the above principle, as it is used for roof and floor insulation: screw the battens, previously treated with wood preservative paint, and apply the insulation in the gaps. This is followed by the special film as a vapor barrier and boarding with wooden panels.

You can easily insulate exterior walls by applying Styrodur or Styrofoam to the exterior wall and covering it with plasterboard or wooden panels.

Doors & windows
The insulation of doors and windows is often neglected. However, eliminated cold bridges at leaking points on door and window frames can also contribute enormously to the energy efficiency of your garden house. Joints can be easily sealed with sealants such as silicone. Applying so-called sealing tape is also an option. We recommend choosing double-glazed windows for your garden shed. Ideally, you should even have them installed by a professional. This can ensure that no gaps and gaps remain, which can cause heat loss and the penetration of moisture.

Dangers of missing or inadequate insulation
Especially if you use your garden shed to house garden furniture, to overwinter your delicate plants, or as a year-round hobby and recreation space, careful insulation makes sense. This is because a lack of insulation or inadequate insulation can have far-reaching consequences.

With insufficient insulation, energy consumption and thus heating costs increase extremely – especially in the cold half of the year. Logical: If the garden house is not insulated or only barely insulated, heat can escape quite easily through the floor, the roof or the walls. In addition, inadequate or missing insulation creates so-called thermal bridges. Here, the heat is lost faster than in other places in the garden house. The result: moisture forms, and in the worst case, condensation can even form. This in turn promotes mold growth and thus damages the summer house in the long term.

It is also important to leave a gap between the insulation material and the boarding. Only in this way is sufficient and natural air circulation possible, which protects the insulating material from moisture and thus from mold growth. This also has an additional positive influence on and strengthens the insulating effect.

Another tip:
Be sure to treat all wooden parts and especially the wooden planks, between which you install the insulation, with wood preservative paint. This not only increases the service life of the wooden component, but also protects the wood and consequently the insulation material from moisture and mold.

Frequently asked questions

Here you will find answers to questions that we are often asked.

Is it possible to insulate on wood?

Insulation on wood is not a problem either. It is even particularly easy to implement, as only a few aids and tools are required. Be sure to leave a gap between the insulation material and the boarding. This ensures sufficient air circulation and prevents mold growth. We also recommend treating the wooden parts with wood preservative paint.

Is it possible to insulate a roof from the inside?

Yes, a roof can also be insulated from the inside. In this case, the so-called inter-rafter or under-rafter insulation is used. The insulation material is clamped between the roof beams, covered with foil and boarded. Ideal to insulate your summer house even afterwards.

Which insulation for summer house?

Especially popular is insulation with mineral or wood wool. But insulation with perlite or Styrodur is also suitable. All these materials can be easily processed and cut even by laymen. When insulating with mineral and wood wool, however, you should always wear protective clothing, as the material can irritate mucous membranes and damage the respiratory tract.

What does garden house insulation cost?

Here it depends on the insulation material and its quality. For insulation with mineral wool you have to calculate with about 5-15 €/m², for perlite fill with 15 $ /100 l and for hard foam boards made of Styrodur the costs amount to about 5 €/m².

How can I insulate my garden house?

In any case, we recommend a so-called multi-layer insulation system, in which your summerhouse is insulated all around (floor, roof, walls). This way you reduce energy consumption and lower heating costs. The principle is always the same and quite simple: first apply wooden planks to the surface to be insulated. Then place the insulation material of your choice in the gaps and cover the whole thing with a diffusion-open special foil. Finally, the boarding follows.


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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