A log cabin can be used in any month of the year if it is built with enough insulation to keep warmth in and drafts out. It’s best to decide to insulate a log cabin when purchasing the building, as the construction phase is the easiest time for installation. We recommend at least roof insulation to keep heating costs low and & maintain energy efficiency.
With the huge rise in log cabin installations in recent years, many of us are turning to them as a way to add an additional room to our homes. A log cabin can easily be used as a home office, gym or even a bar. And we want to take advantage of our shiny new garden building in all months of the year. Why should we be limited to use just over the summer?
Being in the UK, the biggest challenge for any log cabin owner is often the weather. Hot summers and cold winters make it important to ensure the building can provide a comfortable environment throughout the year. Like most, we have an electric heater inside our cabin to raise the temperature when it’s cold outside.
While electric heaters provide great heat output and can increase room temperature in a matter of minutes, they are very expensive to run. Many are designed for occasional use, and using a heater every day in a log cabin can soon increase your energy bills.
Running a 1.5kW heater for an hour per day inside your log cabin could add nearly £90 to a standard annual electricity bill.
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Installing insulation from the start can reduce energy costs and cut the amount of heat lost during the winter. Fun fact – during the summer, insulation also helps keep the cabin cool by reducing warmth transferring through the insulation & into the interior.
Table of Contents
Before we begin
- Cabin wood treatment
Once the insulation is installed and sealed into place, it is difficult to get access to the wood which is covered up. We like to cover the wood in a treatment before installing insulation to avoid any dampness or mould from damaging the wood in years to come. While some log cabins come pre-treated, many will not so it’s worth checking with your manufacturer.
Wood preserver is a clear solution that is applied to fresh wood as a base coat before any other covering e.g. paint is applied. The aim is to protect against rot and decay to keep the wood stay looking new and avoiding breakdown over time. Wood being between the warm and cold creates an ideal location for mould without adequate ventilation. We used Cuprinol clear wood preserver but there are many similar products available.
- Types of insulation
Insulation is available in a selection of different products including boards, rolls and foam. For insulating a log cabin, we recommend using PIR insulation boards. The boards are made up of a lightweight rigid foam which is ideal for mounting in between the framing of a log cabin. The fire safety value is also high, an important consideration in a wooden building.
Insulation boards also offer extremely high-efficiency values, often higher than other insulation products with the same thickness. While different thicknesses are available, we recommend using 50mm thickness as the sweet spot between ease of installation, cost and energy efficiency. Insulation boards can be purchased from most home improvement stores or builders merchants.
Other choices of insulation are available such as rock wool. For a log cabin, we would avoid these as they can be difficult to install, particularly on the roof. While they are good for wall insulation, most log cabins will only feature insulation in the floor and roof.
- As well as insulation
While insulation will have a large impact on the energy efficiency and warmth inside a log cabin, additional steps can be used to increase heat retention further. Double glazing is an optional extra on most log cabins. For buildings with thicker walls, windows become a bigger source of heat loss and we recommend purchasing double glazing for cabins with increased wall thickness.
Furnishings inside can create a feeling of warmth and are a good choice for cabins used throughout the winter months. Curtains and carpets reduce drafts and create a warmer atmosphere when you enter the cabin.
Do the walls need insulation?
A common question is whether log cabin walls need to be insulated. Unlike summerhouses, log cabins often do not need wall insulation and instead we only insulate the floor and roof.
A choice of thickness is offered with most log cabins and standard options include 28mm, 44mm and 70mm upwards. We recommend a 44mm wall thickness for using a log cabin in all months of the year without the need for wall insulation. 44mm provides thick logs with a double tongue and groove system to fit tightly together and lock in heat. The wall thickness alone is enough to maintain warmth and keep the cold out. Increased thickness such as 70mm buildings often feature insulation already integrated into the walls as standard.
With 28mm thickness, the choice becomes a bit more difficult and will depend on how you plan to use your log cabin. 28mm is already several times thicker than the wood you would find in a shed or summer house. A single tongue and groove system is used to keep the wood locked into place and secure. Without insulation, a 28mm cabin is thick enough for use in spring, summer and autumn.
For use during the winter or for static activities such as sitting at an office desk, we would recommend installing insulation. Installing insulation to a log cabin wall requires interior framing to be fitted. Insulation boards can be cut to shape and placed tightly in between the framing. The walls will be boarded over with a material such as plywood to seal the insulation in place.
Insulating a log cabin floor
Depending on where a log cabin is purchased from, the flooring can come in different set-ups. Before installing insulation, it’s a good time to consider using a vapour barrier. The vapour barrier will stop damp rising from a concrete base below and affecting the wood over time.
To install insulation, we need wooden framing underneath the cabin where the insulation board can slot in between. Many log cabins will feature these as standard and they should be pressure treated in advance where possible.
The insulation board is cut up and placed tightly in between the framing. The idea with rigid insulation boards is for it to be tight enough to stay firmly in place. Place the boards level with the top of the wood framing and there should be space underneath for air to flow and prevent damp. Screws or a small piece of wood can be used to keep the insulation board in place if required.
Once all of the insulation boards have been installed, foil-backed insulation tape is used to seal the edges and avoid any gaps along the wood framing. This creates an airtight seal and reduces draft where the insulation board meets the wooden framing.
Once the insulation is installed and the cabin built, we can go ahead and install our flooring. The floor is placed directly on top of the wooden framing. Different choices of flooring are available including OSB board, plywood and tongue & groove.
Insulating a log cabin roof
Installing insulation in a log cabin roof poses a bit more of a challenge and there are several methods to do so. The most popular method is to create a ‘warm roof’ which leaves the internal beams exposed and is also easy to install.
Once the log cabin roof boards are installed, we place the insulation board on top before installing the shingles or roof felt. We recommend first installing a vapour barrier above the boards to keep them protected and stop any moisture from passing through.
After the vapour barrier is installed, we lay the insulation board on top, cutting to fit the shape of the roof and going all the way to each edge. Where insulation boards meet they can be taped over to create a waterproof seal.
Roof shingles can then be installed and nailed through each insulation board. Nails that are long enough to go through to the wood boards are required to keep everything firmly in place. Working with a small section at a time makes it easier to navigate around the roof and complete the installation. After the insulation has been installed, wood board (e.g. OSB) could also be placed over it before the shingles or roof felt is installed.
Alternatively, a log cabin roof can be insulated from the interior, similar to how summer house installation is installed. Insulation board can be cut to shape and placed in between the eaves of the roof. For log cabins with thick eaves, a good thickness of insulation board can be used to maximise R-values. A gap is required between the insulation board and the roofing board to allow airflow and avoid dampness. Foil-backed tape should be used just like when insulating the floor.
Once installed, the ceiling can be boarded with plywood or similar to lock into place the insulation. The downside with this approach is that we lose the look of the interior eves which are a great feature inside a log cabin.
Some useful info
When should I consider electrics?
Electrics may need to be considered before insulation depending on where the insulation is installed. If walls are being insulated, a first fit of electrics will need to be carried out to run the electric wiring through the walls before they are boarded over. If only the roof is being insulated, electrics are less of a concern as they can be fitted after.
Will my log cabin need ventilation?
Log cabins with little ventilation can lead to moisture build-up over time. This is particularly true for users spending long periods of time inside. A passive ventilation system will allow warm and moist air to exit the log cabin and be replaced with fresh dry air. This process stops moisture build-up and reduces the risk of dampness or condensation.
A small passive air vent can easily be installed on a log cabin and many will feature ventilation as a standard feature.
Overall, insulating a log cabin is the perfect way to enjoy the building throughout the year. An uninsulated building can lead to expensive heating bills as the warmth escapes and needs replacing by an electric heater.
For most log cabins, only floor and roof insulation is required. We recommend using insulation boards as they are easy to install and provide excellent thermal values.
Let us know in the comments how you will be insulating your log cabin.