Do Logs Insulate Well? How to Get a Log Cabin to Hold Heat

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A rustic log cabin can have a lot of charm and be one of the most fun and relaxing places to spend your free time.

But what about in the winter?  Are log cabins capable of keeping you warm in really cold climates and at the heights of winter?  Do log cabins even have insulation?

Log cabins can be really warm year-round if they’re built well.  There are a lot of log cabins in cold climates like Canada and Alaska. But a traditional log cabin doesn’t have insulation—the logs are the insulation. A 6-inch pine log has an R-value of about 8.4 which insulates less than stud-framed walls that have an r-value of about 14.

But there are a lot of ways that log cabins actually do a great job of keeping you warm, even through a really cold winter. The r-value of the insulation is only one of many factors that determine how well a building can keep you warm.

Log Cabin Wall Insulation

Log cabins don’t usually have any sort of wall insulation.  With actual log cabins where the structure is made of up solid logs, not just a framed wall with log-looking cladding, you can’t really put insulation in the wall.  It’s made of solid logs…

But here’s the thing about solid logs.  They actually make up both the structure and the insulation for log cabins.

Insulators are just materials the prevent heat from transferring from one side to the other very efficiently.  So a good insulator keeps heat from inside your cabin from going outside in the cold months, and it keeps heat from outside your cabin from coming inside during hot months.

For a lot of typical modern construction, we build our walls out of a frame made of wood studs.  On the outside, we put up wood paneling and then some sort of finish like siding or stucco.  We then fill the gaps between the studs with insulation.  This is just a material that slows down the flow or transfer of heat.  Obviously, there’s all the electrical and plumbing that gets done before insulating, but that’s not part of this discussion.  Then we put some sort of finish material on the inside of the wall.  Typically this is sheetrock, also known as drywall, that we tape up and paint to give a nice, clean, finished looking wall.

But log cabins don’t have all those layers.  They have logs.  Solid logs.  But as I said above, the logs are the insulation.

So are logs as good as good at insulating as the insulation in a framed house?  If we’re talking strictly about R-value, which is a measure of how well the insulation prevents heat transfer, then no.  With regular fiberglass insulation in a 2×4 studded wall (the most common today) the R-value ends up being about 14 when you add up all the layers.  On the other hand, a 6-inch thick log made of pine will have an R-value of about 1.4 per inch.  So a 6-inch thick pine log will have an R-value of 8.4.  Higher numbers are better, so a 6-inch thick log won’t slow heat transfer as well as studded wall construction.

But R-value isn’t the only thing at play in log cabins.  Read on to learn about the heat batter effect.

The Heat Battery Effect

A battery is just something that stores energy for later use.  We’ve probably all used batteries to run various electronic devices.  Well, your logs in your cabin actually act like a battery that stores heat.

In the daytime, the sun shines on your cabin and heats up the logs.  Even if it’s cold outside, that direct light from the sun can actually do a lot of heating, especially on darker surfaces.  This effect is particularly prevalent in climates where the daytime is significantly warmer than at night.

So here’s what happens.  All day long, your logs are being heated from the sun.  They’re also being heated from the inside by whatever heat source you have (furnace, fireplace, wood burning stove, etc.).  Then at night, when it gets cold outside, the logs will slowly release their heat, and some of it goes back into the cabin.  This doesn’t completely outweigh the lower R-value, as this effect adds about 0.1 per inch of thickness.  This means that a 6-inch thick pine log will have an R-value closer to 9.  But if your logs are 8 inches thick, you will end up with an R-value of 12.

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Where You  Lose Heat in a Log Cabin

So it turns out that log cabins really aren’t bad for keeping the temperature comfortable.  But there are definitely a few things places you want to make sure are insulated.  Here are some of the places where log cabins tend to lose the most heat, and what to do about them.

Out the Roof

You’ve probably heard the phrase “heat rises”.  That’s generally true.  Especially when it comes to air.  Hot air is lighter than cold air which is why hot air balloons work.  So warm air in your cabin will tend to rise to the ceiling.  And unless your roof is actually insulated, it will have a lower R-value than your log walls.  Cabin roofs aren’t usually built out of solid logs.

People tend to like their vaulted ceilings in cabins.  In houses, we often have attic spaces above most rooms and we can just blow insulation into the attic to keep the heat from going up and out the roof.  But when ceilings are vaulted, you can’t do that.  Instead, you have trusses and some sort of wood cladding or paneling on top.  They then put their roofing material (like shingles) on top of that.  In some cases, people will use metal roofing and have it open to the cabin.  In each of these cases, the R-value of the roof will be really low and you’ll lose a lot of heat.

So if you want to keep your cabin temperature comfortable, you should definitely make sure you insulate your cabin roof.  There are multiple options for this.  You can put your wood cladding on the bottom side of the roof trusses and use fiberglass insulation between the trusses, just like we do with studded walls.  Or you can put your wood panels on the top of the trusses, add a layer of insulation, and then another set of wood paneling followed by the roofing materials.  Some people really like to go this route because they want their beautiful wood trusses open and visible on the inside of the cabin.

Your best bet will be to speak to a roofing contractor in the area who has worked on cabins to get their input on what options would be best for your cabin.

Through the Floor

While heat rises, people often still lose a lot of heat through the floor.  This is especially true if you have wood flooring with nothing beneath it.  For a lot of cabins, people build a block or concrete footer that goes around the base of the outside walls of the cabin.  Then, they lay floor trusses across the footer and build their floor on top of that.  The problem with that is that a single, thin layer of wood is all that stands between your feed and the ground.

The ground acts as a heat sink.  What that means is that heat transfers well through the ground, and the ground is so big that it can basically absorb heat continuously.  Since it can transfer heat quickly, you never really warm up the ground.  No matter how much heat it sucks out of your cabin, the ground under your cabin will stay cold and keep absorbing heat.  Because of that, it will draw heat all day and all night when it’s cold

That’s why I recommend insulating your floor.  If you have a concrete slab, you’ll get some but not a lot of insulation.  If you don’t have a concrete slab it’s a really good idea to add insulation between the floor joists under your floorboards.  Again, I recommend you talk with your contractor about the best way to insulate your cabin floor to make sure you’re not losing a lot of heat that way.

Via Air Gaps in the Walls

A well-built log cabin can actually be more air-tight than most stud-frame homes.  The solid logs allow for very little airflow in and out of the cabin.  But there are some places where log cabins can let in a draft if you’re not careful.

One of the places that can develop leaks if you’re not careful is between logs.  Every joint, whether it’s between logs on a wall or at the corners is a potential air leak waiting to happen.  When building the cabin, you need to make sure the chinking (the filler between logs) does a good job of sealing any gap between the wood.  You should inspect the chinking at least a couple times a year to look for cracks.

You also get air gaps anywhere that the logs meet up with another material.  This happens at every opening, like doors and windows.  Make sure that the caulking around the door frames and windows at least visibly seals any gaps.  After your caulking and chinking are done, you can shine a light on one side of the wall and if the light doesn’t shine through the wall, you should have a good seal.

It’s not that cabins need to be airtight.  You just don’t want big enough gaps that you get a draft in your cabin.  And good caulking and chinking will do the job to make sure your cabin walls keep the heat where you want it.

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