Staying Warm In Your Log Cabin: How To Insulate Your Log Cabin

Logs are naturally great insulators and therefore my log cabin will automatically be energy efficient and my bills will be reduced, right? WRONG.

I hear many people making this assumption, but the fact is, up to 70% of your heat will be lost through the roof and the floor.

Couple this with a log home that has been built with logs that are too thin in diameter, or a cabin that has not been built well, you could be well on your way to having a very energy inefficient home. The very opposite of what you set out to achieve I’m sure!

Make certain you don’t make this mistake by ensuring you spend time during the planning and design stage and think about how to insulate your log cabin and make it as energy efficient as possible.

Read on to find out more about the process of insulating your log home, materials to use and step by step instructions of the process.

Why insulate your log cabin home?

Why insulate your log cabin

To understand more about how energy efficient a log cabin is, you need to understand some terminology.

R-Value

The R-Value is the measurement of resistance of heat flow through a certain thickness of material. The higher the R-value the better because the more thermal resistance the material has and therefore, the better insulator it makes.

U-Value

The U-Value measures the heat loss in Watts through a material so therefore the lower the U Value the better as less heat is lost. U values take into account more factors and are therefore more accurate in determining a materials insulating ability.

These values are purely dependant on the type of wood you use for your logs and the thickness of the logs. Typically the R-Value for wood ranges from 1.41 per inch for softwoods and 0.71 per inch for hardwoods. This means a log wall built with a 6-inch softwood logs has an R-value of just over 8.

Compare this to a typical wood stud wall with 3.5 inches of insulation, sheathing, and wallboard which has an R-value of around 14 you may be surprised to see that comparatively log walls are less energy efficient.

However, because of the properties of logs and their ability to store heat, they don’t tend to feel as cold as their given R-value as they can release heat back into the house as it cools – an advantage log homes have over their competitor conventional homes.

Log cabin walls

Rustic Log Cabin Wall

When choosing your logs, you should choose the thickest and best quality logs you can afford, especially if you live in a cold climate.

You need to ensure that your cabin is built well with seamless air-tight joints to maximise energy efficiency and stop drafts. If you are only going to do one thing to your walls in terms of insulating, you need to chink them. Chinking is a flexible sealant used to seal in between the logs; you can read more about the process of chinking here.

Due to the nature of logs, they expand and contract throughout the year; in the winter, logs will expand, and in the summer month they will contract. They are still likely to do this even if they have been kiln dried.

With this in mind, your log cabin can vary in height throughout the year quite considerably so if you were to fix studding and cladding to the walls to add insulation to them, you would restrict the natural movement; this could result in gaps appearing in your walls and therefore make it less energy efficient.

If you have used thick enough logs you probably will not need to insulate your walls any further, however, some companies do offer wall insulation in the form or either a sliding bracket system that doesn’t restrict the log movement, or a twin skin wall with insulation in between.

I would not recommend a twin skin wall due to the nature of the logs shrinking and expanding; having two walls rigidly fixed together is a recipe for disaster!

The two areas I would absolutely recommend insulating are your floor and roof.

Floor Insulation

Floor insulation

Approximately 70% of heat escapes through the floor and roof, it is therefore essential to insulate them well.

Insulating your log cabin’s floor can save up to 20% of your annual heating costs when fitted properly and combined with the finished floor.

First steps first, you should install a moisture resistant membrane such as Tyvek, this will prevent damp from rising and keep the underneath of your cabin dry as it acts to stop water coming through but allows water vapour to escape.

Once your membrane is in place, you will need to lay thin pieces of wood to raise your log home off the ground. If your log cabin is already raised off the ground slightly, or is on stilts, you will still need a moisture resistant membrane and you can continue with the steps below.

Secure your joists onto the lathing and attach batons to the joists to support the insulation. When attaching the batons, keep in mind that you will need to leave around a 50mm gap between the membrane and the start of the insulation to allow air flow to remove moisture.

Joists are horizontal members or beams which run parallel between the foundation to support a load.

Once the membrane and joists are in place, you need to cut the material you are using to insulate to the right size to fit perfectly in the cavities made by the joists.

By making sure the insulation fits snugly, you will avoid cold spots in the flooring.

The top of the insulation should sit flush with the top of the joists, and the flooring should lie directly on top. Your insulation should be at least 50mm deep to work efficiently.

Log cabin roof

Log cabin roofing

If you want to insulate the inside of your roof you need to flip the process round for insulating the floor.

Most people who build a log cabin will want the beautiful detail of the high roof and rafters to be visible from the inside, unlike many regular buildings when the ceiling is boarded up flat to form a box shape room.

It is for this reason that many log cabins will have the insulation on top of the log cabin. Your log cabin should be completed to roof rafter level and the roof should then be sheathed with your boards; I would recommend using good quality aged boards rather than plywood to add to the rustic feeling of your cabin.

You will then need to cover your roof with moisture resistant membrane such as the Tyvek or Kingspan as mentioned before. You will need to staple your membrane down onto the boards. This is great because it will stop the warm air from your cabin escaping into the layer of insulation.

It is then time to add your insulation and there are a great many to choose from. If you are sticking with sheets, you will need to add batons to your roof to encase the insulation.

Your batons will need to be put around the edge of your roof and spaced out evenly along the length of your roof. You can then cut your insulation to size to fit in between. Similar to your floor, you should leave a small air flow gap so make sure your insulation doesn’t sit flush with the very top of the rafters.

After this step, your roof is ready to finish as desired; there are a great many options to finish your roof.

Insulating materials

There are many different types of insulation you can use, from manmade materials like Kingspan and Celotex, to natural materials such as recycled wood fibre or sheep’s wool.

This will depend on your budget and the resources available to you in your area and personal preferences.

Log cabin Double Glazing

Log cabin double glazing

You may also want to consider having double glazing to maximise your energy efficiency.

If you’re building in a cold climate you definitely use logs that have a diameter of at least 10 inches, however if you are building in Europe or a warmer climate, your logs may not necessarily be as large depending on the purpose of your log cabin.

Double glazing is only worth getting in lob cabins that have walls with logs of a diameter of at least 58mm.

Any less than that and the walls are actually not as effective at insulating as the windows, in other words, more heat will escape through the walls than the windows.

See the values below to make more sense of this:

Material R Value U Value
Single pane of glass 0.94 1.10
Double pane of glass 1.93 0.52
28mm Spruce Logs 0.29 3.42
45 mm Spruce Logs 0.45 2.21
58mm Spruce Logs 0.61 1.64

As you can see, you will only start noticing the benefits if your logs are thicker than 58mm – this will not even enter in the question for cabins being built in a cold climate as the logs should be much thicker than that.

So there you have it, don’t underestimate the importance of insulation if you are planning on having an energy efficient log home which is liveable in all year round.

You should give this thorough thought during your planning and design process and remember that the two most important areas to insulate are the floor and the roof.

Couple this with well-built, air-tight walls and double glazing and you’ll have a log home which will be able to maintain a good temperature inside all year round.

What is your reason for reading through our article today? Are you just about to start planning your log cabin insulation, or are you looking for a way to make your current log cabin more energy efficient? Let us know and drop us a line below!

Comments

  • Hi, we purchased a 30 year old log home and it has no chinking inside. It is winter and we can feel cold air coming through some of the gaps between the logs and some logs have shifted quite a bit. Can we stuff the holes between some of the logs with something or is chinking required at this point?

    Thanks a lot,
    Evelyn

    • Hi Evelyn,

      You can cover the gaps with other types on insulation yes, but chinking will provide the best finish in my experience.

      David

  • We have purchased a log timber framed home built in 1982. It is located in the Pacific Northwest on the Olympic Pennisula in Kingston Washington.
    My concern is that with the high ceilings and no additional insulation, this will be a monster to heat and cool. I would like some info on how to insulate the roof frtom the inside, as the previous owner recently replaced the metal roof.

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