When lining the interior of a garden building, there are many aspects to consider. Interior walls improve the appearance, insulate heat, protect against condensation and allow for fixtures & fittings.
Garden buildings such as summerhouses and sheds are a great choice to convert into a room in the garden. An increase in popularity over the last few years has led to many homeowners ditching the extension and opting for a garden room instead. As well as avoiding lengthy planning applications, converted sheds & summerhouses cost significantly less and can be completed within a few months.
There’s plenty of great uses for a garden room including as an office, a man cave or even as a garden bar. For use throughout the colder months of the year, we need to take additional steps during construction to improve heat retention. Many sheds and summerhouses come with 8-12mm thickness timber walls that on their own are not suitable for use when the temperature begins to drop.
Creating a garden room that can be used during the winter involves insulating the walls and then lining the interior walls to cover the insulation. The wooden framing inside a summerhouse or shed creates the perfect cavity to install insulation. Once insulated, the walls can be boarded over, allowing for the interior to be decorated. Lots of choices are available on the material for lining the walls and plasterboard is a common consideration.
Can I plasterboard my summerhouse or shed?
Plasterboard can be used to line the interior walls of a summerhouse or shed, so long as the structure has been insulated and has a vapour barrier in place.
Using plasterboard is a popular choice when converting a summerhouse or shed and aiming to achieve the look & feel of another room in the house. Once the plasterboard is installed, it can be skimmed over and then painted to decorate the interior.
For the outbuilding to be suitable for plasterboard, it must first be insulated and protected with a vapour barrier. There should also be a heat source such as a small electric heater. Insulating a summerhouse or shed is easy and the wooden framing provides the perfect space to place insulation in between. Several different types of insulation are suitable including multi-foil and wool insulation roll, but we recommend using rigid insulation boards.
The insulation boards are cut to size to fit tightly in the gaps between the timber battens inside. This will result in the insulation sitting flush and the plasterboard can be attached to the battens. If electricity is going to be installed in the garden room, a first fix of the cables can be completed before the plasterboard is installed to keep the wires hidden neatly behind the interior walls.
A vapour barrier is essential to avoid damp problems and prevent water from building up behind the plasterboard inside the walls. As plasterboard offers little moisture resistance, the warm humid air from inside can penetrate into the walls, where it cools to droplets and leads to damp issues over time. Eventually, this could lead to crumbling plasterboards and rot forming on the timber inside the walls.
A vapour barrier is an impermeable sheeting placed on the warm side of the insulation to prevent vapour from passing through and into the wall. This prevents the vapour cooling when it comes into contact with colder air and leading to condensation.
The foil in foil-backed rigid insulation boards can act as a suitable vapour barrier for a converted summerhouse or shed. The edges of the insulation can be covered using aluminium tape to complete the barrier and improve airtightness. Other types of insulation such as wool insulation roll will need separate plastic sheeting to make them suitable for use with plasterboard.
Considerations when using plasterboard
While the appearance of plasterboard inside a garden room looks great, it can pose some additional challenges compared with using other materials.
Plasterboard is not the most durable material to line the inside walls, as it’s vulnerable to knocks and bumps. If the garden building is going to be used for storing items such as garden equipment, it may be better to use stronger wooden boarding in areas that could easily be knocked when passing. For converting a summerhouse into a garden gym, a strong and thick wood such as OSB is most suitable.
If the plan is to hang shelves or even a TV onto the walls, plasterboard does not offer much strength and may begin to crumble or break with the weight of anything attached. For small shelves, we can attach them in position with the timber battens behind to increase the strength. Plasterboard itself will not hold the weight of a TV or speakers and that section may require another material such as plywood that has more strength.
As a garden room with plasterboard will contain a vapour barrier and have a high level of airtightness, we recommend installing an air vent. Trapped humid air inside the garden room can lead to condensation and damage to the plasterboard. A small air vent allows for air to circulate and the humid air to be constantly replaced with fresh dry air. For a large garden room, several air vents can be used.
Guide: Does a summerhouse need a vapour barrier?
Which is the best material for lining a summerhouse or shed interior?
The best material to line the interior of a summerhouse or shed will depend on the look aiming to be achieved and the budget available. While plasterboard looks great, it does come with some considerations and potential drawbacks that are not found with other materials.
Plywood
Our favourite material for lining the interior walls of a garden building is plywood. The engineered wood is created by glueing lots of pieces of veneer together, each at a 90-degree angle. Due to its construction, plywood is very strong, making it a great choice for all garden rooms and especially areas where it might get knocked. If items are going to be attached to the walls, plywood often makes the best choice.
Due to its strength, a thinner piece of plywood is often required compared with other materials. This makes it easier to work with and will take up less space once installed. The challenge with plywood is that it can be expensive, especially for larger garden rooms. When painted, the grain of plywood can show through but this can be partially sanded down.
Shiplap
The exterior of a summerhouse or shed often contains shiplap (or similar tongue & groove) but it can also be used for the interior walls as well. Shiplap refers to the shape of the wood and the actual material is timber, the same as the rest of the construction of the outbuilding. Unlike other options for the interior wall lining, shiplap does not come as large boards. Instead, each individual panel is slotted together which can make it easy to work with but can take a long time to complete.
Shiplap is often thick enough to provide some heat insulating benefits and also looks great on the interior of a garden room. The same material can be used for lining the roof as well. Once installed, the shiplap can be painted and decorated easily and the wood remains smooth.
OSB
OSB is formed by compressing lots of layers of wood strands together and adding adhesive. It is commonly used where strength is required and makes a good choice for attaching fixtures to the interior walls. OSB is easy to spot due to its unique texture which is slightly rough with visible strands. While it does look better painted, the texture is still visible and make not be the best choice where a smooth finish is required.
Many different thickness options are available for OSB and it’s also much better value compared to plywood. Oriented straight board comes in different durability ratings and OSB3 is most suited to a garden room due to its increased moisture resistance and lower swelling rate.
Guide: How to prevent mould in a summerhouse
How to prepare a summerhouse or shed
Before installing plasterboard inside a summerhouse or shed, it’s important to make sure the outbuilding is prepared. Issues such as gaps in the wood and no heating inside can result in the plaster becoming damaged or beginning to fail.
Check the structure is watertight
If an older garden building is being used, it must be completely watertight before installing plasterboard. As timber buildings age, the wood can move slightly, resulting in gaps where the panels join together. Even a small gap in the wall can result in rot if there’s nowhere for the water to escape. Holes in the wall also allow heat to escape and create a draft during the winter.
Start by inspecting all of the way around the building for any sign of damage and also check the roof. If it’s due to rain, be sure to take a look inside the outbuilding after to make sure water has not got in. If there are any gaps, a sealant or wood filler can be used to cover them.
Wood treatment
Timber garden buildings are vulnerable when exposed to weather conditions and over time can become damaged or warped. While the outside of a garden building is often treated, the interior walls are commonly missed out. If the walls are going to be sealed with insulation and a wall lining, we recommend applying a wood preserver first to avoid issues with dampness and rot if any moisture gets into the wall cavity.
A clear wood preserver can be applied to the interior walls and will protect against fungal growth, insect attack and rot. Once the plasterboard has been applied, it provides peace of mind the walls behind are protected.
Heating
For a summerhouse or shed lined with plasterboard, a heater inside will prevent any damp and freezing conditions that could damage the plaster during winter. To use a heater inside a garden building electricity is required and should be installed before the plasterboard so the wiring can be put into position behind the wall. An armoured cable is usually connected from the fuse board in the main property and buried underground.
Lots of choices of electric heaters are available for a garden room. A small oil-filled radiator is ideal to keep the room warm and provide background heat when used as an office or bar during the colder months. Fan heaters are also popular and provide instant warm-up.
Guide: Best heaters for a garden room
Summary
Garden buildings are an increasingly popular choice for use as a bar or office and decorating the walls can transform the interior. Plasterboard is an option to consider, so long as the structure has been insulated and a vapour barrier installed. Further considerations with plasterboard include whether fixtures will be attached to the walls and avoiding areas prone to knocks from garden equipment.
Plenty of other choices are also available and our favourite is plywood. Despite being expensive, the material is extremely durable and easy to work with during installation.
What is the best vapour barrier to use if using wool to insulate ?
A polythene vapour barrier can be installed before the plasterboard to protect against moisture.
How thick plywood should i use for an 8 x 6 shiplap summerhouse?
We have used 9mm on a summerhouse interior that creates a solid interior wall. However, similar thickness levels are also suitable depending on your requirements.