Garden rooms are designed to be an extension of your home and can add significant value.
The biggest benefit of a garden room is that they’re designed for year-round use. Garden room insulation makes this possible.
Table of Contents
Garden Room Insulation
Once you have completed your Garden Room Frame, you need to Consider which type of insulation to use.
By adding insulation to your garden room you will achieve two things.
- You will help improve the thermal efficiency of the Garden Room. Any heat within the building will be trapped inside and escape much slower. This will help reduce heating bills.
- During the summer, heat will be kept out, keeping the interior cooler.
Example heat loss:
- 25% through the roof
- 35% through the walls
- 10% through the windows
- 15% through the doors
- 15% through the floor
Types of Garden Room Insulation
Polyurethane Insulation (PIR)
Polyurethane insulation is commonly used for Garden Room insulation. It is one of the most efficient thermal insulation materials, therefore enabling energy savings with minimal thickness.
The boards have a PIR foam
core with facings of aluminium foil.
These boards are typically manufactured in sizes of 2400mm x 1200mm. These are rigid self-supporting boards that just need cutting to fit the required gap, however, they can be messy to cut, creating a lot of dust.
PIR insulation has a very low thermal conductivity of 0.022 W/mK or a high R-value. This means that building
elements, such as walls, can be thinner while still achieving a high insulation value. therefore, It’s a great choice for your Garden Room Insulation
Mineral wool Insulation
Mineral wool insulation (also known as rock wool insulation) has a low thermal conductivity of 0.037 W/mK or a high R-value. This is not as efficient as PIR. As a guide, the wool application would need to be twice as thick to achieve the same value of insulation.
It has excellent flame-resistant properties and is also an acoustic dampener which makes it a great material to use in the walls for sound deadening.
Mineral wool insulation is very flexible making it easy to install and fit into awkward gaps compared to PIR, and it is much cheaper.
Its flexibility means it is not self-supporting, so when installed in walls it could sag under its own weight if it doesn’t have support to keep it in place.
Because of the structure and composition of the material, mineral wool insulation offers good protection against noise.
Also, it does not encourage vermin and also the growth of mold or fungi
Cavity slab Insulation
Cavity slab insulation is used in cavity walls. Most cavity slab insulation products can be friction-fitted for ease of use and are self-supporting. Ideal Insulation for the walls of a garden room
It does not encourage vermin and also the growth of mold or fungi
Cavity slab insulation has a low thermal conductivity or a high R-value similar to mineral wool insulation. This is not as efficient as PIR, which means, the insulation would need to be twice as thick to achieve the same thermal value as PIR.
Because of the structure and composition of the material, Cavity slab insulation offers good protection against noise. making it an ideal Garden Room insulation for the walls.
How to insulate your garden room
Garden room floor insulation
Use 100mm Rigid PIR Insulation boards between each joist inside the base and hold them in place with lengths of 2×1″ timber running under the base. Ensure the insulation is a snug fit and fill any gaps with expanding foam.
Garden room wall insulation
Depending on your budget, you can insulate your walls using either 100mm Wool insulation, 100mm Cavity slabs, or 50mm PIR boards. Each one creates a similar amount of insulation
Garden room roof insulation
Use 75mm Rigid PIR Insulation board in the roof. This sits between the rafters, and the rafters are usually 125mm high, which allows a 50mm airflow above the insulation to achieve a “cold roof“.
For Garden Rooms where height isn’t restricted by permitted development rules, You can use 100mm PIR insulation above the rafters to achieve a warm roof. This provides better insulation and the roof does not need to be vented for air flow like a cold roof
Garden room airtightness
To get the most from your garden room Insulation, you should make the room as airtight as possible, this is the key to achieving good insulation. Fill every possible void with wool insulation or expanding foam.
Once your airtight room is achieved, you need to provide ventilation for the moisture to escape and avoid condensation and dampness, this is usually achieved by having at least 2 windows with trickle vents.
Now you have Insulated your garden room, you need to heat it, see our Garden room heating guide below
Top 5 Garden Room heaters for any budget
Which type of garden room heating is best for you? let’s have a look at the different options to heat…
Frequently asked questions
Is 50mm insulation enough for a garden room?
50mm insulation is enough for the walls if using PIR, but the floor and roof should be 75-100mm thick PIR.
What thickness insulation for a garden room?
Are garden rooms warm in winter
With the correct insulation and a small heater, A garden room can be warm enough to use in winter
What is the best insulation for a garden room?
PIR is the best insulation to use, It is twice as efficient as wool insulation, making it perfect for thin walls, and the rigid boards will not sag over time.
Is it worth insulating a garden room?
By adding insulation to a garden room you will improve the thermal efficiency of the building. Any heat within the building will be trapped inside for longer. This will help keep heating bills to a minimum.
Do you need to insulate the floor of a garden room?
The floor contributes to around 10% of heat loss, so needs to be insulated, to improve the thermal efficiency of the building.
How thick should insulation be in a garden room?
For garden rooms insulated using rigid foam boards (PIR), you should expect insulation to be 100mm thick in the floor, 50mm in the walls and 75mm in the roof.
If using mineral wool insulation, the thicknes should be double that of PIR.
Heating and Insulation
HEATING AND INSULATION ADVICE
Garden Room Ventilation
Garden Room Ventilation Garden Room Ventilation is the process of exchanging air inside a room with fresh air from outside. It is important…
Benefits of an insulated Garden Room
Insulation is important if you want to use your garden room all year round, here’s a guide to the different requirements
Garden Room Insulation, the Ultimate guide!
Insulation is important if you want to use your garden room all year round, here’s a guide to the different requirements