Log cabin insulation: How to insulate your floor and roof
Adding insulation to the floor and roof of your log cabin enables you to turn it into a space you can use throughout the year. The floor and roof are the two places where heat is most commonly lost so adding insulation here can make a huge difference. Proper insulation in these areas helps to improve comfort and energy efficiency, particularly if you’re intending to use your log cabin as a garden office, hobby room or guest space.
Here's our guide to insulating the floor and roof of your log cabin.
Insulating the floor of your log cabin
Before you start insulating your log cabin, we recommend adding a damp proof membrane either within the base or on top of it. This helps to prevent damp getting into your building and causing problems such as damp, mould and rotting.
Floor insulation is usually installed once the main structure has been installed. Set the floor bearers out inside the cabin as usual. Once these are in place the insulation boards can be cut to size and installed between them. In many cases, 50mm insulation boards fit perfectly between the floor bearers.
After installing the insulation boards, the floorboards can be laid over the top in the normal way. This allows you to create an insulated floor system without altering the standard construction of the cabin floor.
To calculate how much insulation you’ll need, measure the length and width of the cabin floor and multiply these measurements together to determine the total square metre area. You can then use this measurement to calculate the number of insulation boards required.
Why floor insulation is important
When buying a log cabin, it’s important to consider how you’re going to use it and whether you want to use it throughout the year. Adding floor insulation can make a huge difference to the comfort of your log cabin in the colder months.
Log cabins are usually raised above ground level on foundation beams which allows cold air to circulate underneath. Without insulation, this cold air can transfer through the floor and reduce the overall internal temperature of your log cabin. Adding insulation in the floor prevents this cold air from getting in, keeps warm air in and provides a more comfortable temperature inside the cabin.
If you want to use your log cabin as an additional living space or office, insulating the floor is one of the best ways to create a space that can be used year-round.
Insulating the roof of your log cabin
Insulating the roof of your log cabin is a little trickier and takes a little more work.
The first step is choosing the thickness of the insulation board you want to use. 50mm boards are a common choice but thicker boards such as 70mm or 100mm can provide higher levels of insulation.
This decision will depend on how you intend to use your log cabin. If you intend to use it all year round, your building may benefit from thicker insulation to improve thermal efficiency.
To calculate the amount of roof insulation required, calculate one side of the roof area and multiply the measurement by two.
When installing roof insulation boards, you’ll need to use longer clout nails to secure the final roof surface, insulation and roof timber boards. If you’re using 50mm insulation, we recommend 65mm nails for the flats of the roof and 70mm clout nails for the ridges.
Lay the boards so they are flush with the leading edge. Bear in mind that this edge will be exposed so consider how you’re going to cover it. In the below example, we were using a 50mm board and tuned the roof trim the other way up.
This portion can be covered later with additional timber, and you will need to source the trim timber locally.
Next, lay one layer of insulation boards and fix into place with one clout nail in each corner and one in the centre. You can then add roofing felt or shingles up to the first board. We recommend doing this instead of insulating the whole roof because you will need to get onto the roof to tile it or add felt, and the insulation can be very slippery.
Once a board is complete with tiles or felt, move onto the next and carry-on adding boards and tiles until you reach the top.
For more tips on installing shingles, read our blog: DIY guide: How to install felt roof shingles on your log cabin.
Finally, install the bargeboards to the front and back of your log cabin. Either move the supplied bargeboard up to cover the insulation boards or double up your bargeboards as shown below. You may need to source this additional timber locally.
The same principle can be applied to a hipped, octagonal and hexagonal roof. The only slight difference is you will finish the corners of the ridges slightly differently by cutting them flush with the ends of the roof boards. You will then cut a fillet to fill in the ‘v’ that naturally forms.
For a well-insulated log cabin that can be used, double glazing is also a great addition. Find out more in our blog: Double glazing in log cabins.
Why insulating your log cabin floor and roof matters
Insulating the floor and roof of your log cabin can significantly improve the comfort, usability and overall performance of the building. While the timber provides a certain level of natural insulation, heat is still likely to escape through the floor and roof.
Adding insulation to these areas makes it easier to maintain a stable internal temperature throughout the year. Insulation can help to keep your log cabin warmer during the colder months and provide you with a garden office, studio workshop or additional living space that makes the space more comfortable and practical to use throughout the year.
When planning your log cabin installation, we recommend considering insulation as part of your build. Insulating the floor and roof during installation will provide you with a more versatile and usable space.
If you’d like further advice and guidance on adding insulation to your log cabin, please contact our friendly customer service team.
