As the winter gets closer and the temperature outside drops, it’s time to begin thinking about heating inside a summerhouse. If the building does not have electricity, alternative options are available.
Despite what the name suggests, a summerhouse is actually suitable for use throughout the year with some modifications. There’s no need to lock up the summerhouse until next spring. Instead, making sure the building has a source of heat and is able to retain warmth is key to using it during the winter.
There are plenty of great uses for a summerhouse throughout the year including as a garden office, outdoor gym or even a bar. Getting constant use out of the building provides maximum value and creates a separate space away from the house.
When the weather is cold outside it can be tempting to stay in the house. To make the atmosphere comfortable inside a summerhouse, we firstly need a source of heat. Electric heaters are the easiest solution, but when there’s no wiring in place to the garden building, we need to consider alternative options. Heat retention is also key to the summerhouse being able to hold onto the warmth inside and keep the interior temperature raised.
Let’s take a look at some of our favourite ways to heat a summerhouse without electricity.

Position for sunlight
The positioning of a summerhouse in the garden can make a massive difference to how warm it feels inside. We can take advantage of the natural heat source of the sun throughout all months of the year. The design of most summerhouses features large glass windows and doors that can let plenty of sunlight inside.
To get the maximum heating effect from sunlight, the summerhouse should be positioned somewhere the sun will be shining on it from morning until evening. The glass windows can be positioned facing the sun as the intensity often feels stronger through glass. Large objects that will obscure the light such as tall trees and fences should be avoided nearby.
A summerhouse painted with dark colours and a black roof will be better at absorbing the heat from sunlight. To maximise the warming effect, consider painting the building in dark brown that still looks great and absorbs heat. But beware during the summer, as too much direct sunlight can make the temperature in the summerhouse too warm to enjoy comfortably.
Insulation
Once the heat is inside the summerhouse from direct sunlight or another source, we need to make sure it’s not easy to get back out again. Most garden summerhouses do not feature any form of insulation and the tongue & groove timber design does not provide much heat retention. A typical summerhouse wall is between 8-12mm thickness which is not enough to prevent heat from being lost through the walls. The roof, floor and windows also provide an opportunity for heat to escape.

While insulation won’t add heat to a summerhouse, it will improve heat retention. There are lots of methods of insulating a garden building, depending on the budget available. A low-cost solution is to use foil-backed bubble wrap insulation that is designed specifically for sheds & summerhouses. The insulation is applied by using staples to the inside of the summerhouse.
The best way to insulate a summerhouse is to use rigid insulation boards. Inside a summerhouse, the interior wood framing for the structure creates the perfect space for insulation to slot in between. The boards can be cut to size to fit tightly inside the gaps. With the insulation installed, the interior can be lined with plywood or similar wood material. The result is a garden building that’s insulated and can maintain the temperature without the need for constant heating. The suns heat from throughout the way can be maintained into the evening to prevent freezing temperatures during the winter.
Guide: How to insulate a summerhouse
Log burner

It may not sound like a great idea to install a wood burning stove inside a timber building, but it can be done safely. Log burners are great inside a summerhouse or cabin to create a feeling of warmth and cosiness, especially during the winter. The comfortable atmosphere is difficult to replicate with any other heating source and produces an impressive amount of heat. The running costs are far lower than electric heaters, as logs are the only fuel required.
When it comes to installing a wood-burning stove, it’s important to get it fitted by a professional. A safe installation is especially important when the garden building is made from timber. The initial costs can be high for the flue and fitting, but these are soon offset by regular use. As the flue leads to outside, a hole in the summerhouse roof is needed and roof brackets are often installed for extra strength. There may be some additional regulations depending on the type of wood-burning being used; it’s best to speak to a professional installer to ensure your stove is completed correctly.
Portable gas heater
As the name suggests, portable gas heaters are extremely easy to manoeuvre around. The heater can be kept inside the summerhouse from October to March and then moved back out again to free up space during the summer. The biggest benefit compared with an electric equivalent is that no wiring is required. Instead, small gas canisters are placed inside the heater and consumed to produce warmth.

The power output from gas heaters is high and many have a rating of 2000 watts. The heat output is instant and the difference can be felt within minutes inside a summerhouse. Refill canisters are also widely available from camping and homeware stores. The best heaters have adjustable settings which control the flow of gas to adjust the temperature. Gas heaters are also safe and one with the CE markings will ensure that strict safety regulations have been met. A downside of using gas heaters is that the canisters will need to be regularly refilled and replaced.
Why won’t solar panels work?
A common question we get asked is whether solar panels are suitable for heating a summerhouse. The answer is that they are simply just not powerful enough to run a heater. Most electric heaters have a power output between 1-2kW as they require a lot of electricity to run.
Solar panels designed for garden buildings are small and have a low power rating. The most powerful panels are only rated up to 200 watts. To achieve this level of power they also need to be running in ideal conditions during the summer, rather than winter. Solar panels on a summerhouse are great for use with low powered items such as lights and phone chargers but are not suitable for heating.
Should I just use electricity to heat a summerhouse?
While there are many alternatives available, electricity can often be the best solution for heating a summerhouse. If the outbuilding is going to be used regularly during the winter, electricity is going to be needed anyway for lighting.
Installing electricity inside a summerhouse can be completed during construction or once the building is installed. A trench is dug in the garden and an armoured cable is laid inside. The armoured cable protects the electric wiring against damage from digging or an animal eating through the exterior coating. A qualified electrician is required to get electrics installed safely in a summerhouse and the job can be completed in a day.
Electric heaters provide lots of choices. Oil-filled radiators work quietly in the background and stay warm for a while after they have been turned off. Fan heaters provide instant warm-up, making them great for quickly adding heat to a summerhouse used as a garden gym. The cost of running an electric heater can be expensive, so insulation is essential.
Guide: Can I plasterboard my summerhouse?
Summary
Even without electricity, it’s possible to heat a summerhouse for use throughout all months of the year. Start with positioning the summerhouse in a suitable position to get plenty of sunlight through the windows to create the feeling of warmth. Portable gas heaters are great for warming the inside space quickly and can be moved around as required. for a cosy atmosphere, a wood-burning stove can be installed.
Before installing any heating in a summerhouse, we need to make sure the outbuilding can retain heat. Insulating the summerhouse walls and roof will stop a lot of the warmth from escaping and reduce the amount of heating required.
Complete guide to heating a garden room
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