Ventilation in Log Cabins

Index for Ventilation in Log Cabins

Ventilation is something that is normally overlooked in a log cabin. Most of the time though it isn’t necessary. If you’re using it all year round as you’re wandering in and out the air will circulate nicely.

The problem comes if you’re like me and leaves it shut up all the cold months, and, no doubt like me you’ll end up with you outdoor furniture which you carefully store for the winter will look like this, which is a bit of a bugger as it was pretty expensive in the first place.


I have seen some advice on the net which said: ‘A log cabin ‘breathes’, i.e. ventilation occurs naturally through the timber walls’.

This is true to an extent but also pretty much tosh and please don’t rely on this statement. Wood, pressure and moisture are clever things but they’re also lazy and want an easy option and the bloomin’ things will take liberties with you and your building.

Basically a log cabin is the same as any other building. It’s an enclosed space and as such heat and moisture can build up, especially if there is not a damp proof membrane within the base. What normally happens is either damp from the base or damp we introduce in the form of damp furniture, damp tools, etc builds up. This will always create a pressure difference in a log cabin.

Pressure Escape

Within a log cabin, regardless of the time of year there is always a slight pressure difference, the inside is slightly higher than the outside. This is because of heat or moisture or just because it likes being a bit awkward.

As I mentioned earlier, it’s lazy and wants an easy route and the most easiest route is through any gaps, no matter how small, it can find. These might be around the windows, the corner connections or even around where the roof boards are joined to the top logs.

I have two log cabins and one of them is ancient, during the winter it is home to a herd of guinea pigs that live free range all the summer months. Now guinea pigs are only small but you wouldn’t believe the condensation and damp they make. The nearest wall to them is this one:

Effects of not ventilating a log cabin

Effects of not ventilating a log cabin

This is a prime example of a log cabin that isn’t vented. Pressure and moisture being more clever than me have exited from this corner connection, it’s looking for the easiest way out and found it. Couple of course with me being even more lazy and the back wall has not been treated in a very, very long time so it’s a perfect escape route.

These marks are often associated with water coming in to the cabin and I will occasionally have an old customer write to me asking about this and perhaps complaining their cabins is leaking. The first port of call is of course has it been treated regularly? What with? Etc. But the next question is has it been vented. Invariably the answer is no and then we find our culprit, especially as it’s left shut up for half a year.


I used to be in the Fire Service, I love a good ventilation lecture and indeed used to give loads but I will not bother here nor will I draw a really good diagram (I did try though). Suffice to say if you are going to keep your log cabin shut up for any longer than a month or two you need ventilation within it.

We supply these:

Log Cabin air vent

Log Cabin air vent

They’re not flashy or close-able but they do the job nicely. You can also find vents in your local diy shop with all sorts of options.

I could now talk about this sort of ventilation in your log cabin:


I won’t bore you though. I think it’s enough that you should consider some sort of ventilation. Ideally you will have one vent low down and one high up. As I said moisture and pressure is lazy, it’s best to give it an easy route out rather than through your windows or corner connection and possibly causing horrible damp spots.

 A shameless plug

I try to be objective in this blog and apply it to all log cabins regardless of manufacturer. But, I will say this, there is a LOT of difference in machining of joints, doors and windows across all suppliers. You may not experience these ventilation problems elsewhere with other manufacturers as the joints are a little loser. Tuindeco provides a high quality product, the joints are extremely tight and pressure will build up within these cabins. A slight downside to the precision machining or perhaps a positive?

15 thoughts on “Ventilation in Log Cabins

  1. Hopefully I will be building one of your cabins fairly soon, pending delivery. I will be putting in my own floor using insulation and also on the ceiling. The type of design means that the roof can only be insulated internally. Would you suggest that I need an air gap on top of the insulation and if so should the floor and roof box sections also be given some vents for them to breathe? I was planning on venting the cabin space also.

    • I only ever recommend fitting insulation on top of the roof. All designs allow for this. If you are putting it inside you will need a void and good ventilation to avoid problems with condensation build up on top of the insulation.

  2. Hi Richard,

    Thanks for the article. I have a log cabin that was installed by another supplier last August (2019) and insulated using a cold roof system with insulating blocks slotted in-between the joists, with T&G board below to cover the insulation and create the ceiling. We have been in and out of the cabin quite often since, so it hasn’t been shut up for months. All was well until earlier this month, when with the onset of warmer weather (May 2020) we started to see water dripping down from the main roof support joist. Realising that the void above the insulation had no ventilation, I have drilled 9x 20mm holes each end of the cabin to let air circulate, but this doesn’t seem to have fixed it. On further investigation (taking down the first parts of the internal ceiling) I have found signs of mould and damp wood, so clearly it’s been a problem for a while. There’s also no vapour barrier installed below the insulation blocks – should there be? I’m also puzzled as to how this has only become apparent in the summer, and why it’s only a problem on the central roof support joist, nowhere else.

    If anyone has any ideas about how to fix this please comment below. I fear the only answer might be to take off the entire roof, remove the insulation, then install and seal a vapour barrier covering the top of the ceiling and all the joists, then re-install the insulation, roof boards and shingles.

    • I’m sorry to hear you have some problems with condensation. This is why I prefer insulation on top of the roof boards rather than inside. Of course that is not always possible if overall height is an issue. I think you will have the problem in the center joist as the warm air will rise to the center. Other than venting it well I don’t know how to solve this for you. If you do have to remove all the roof it maybe worth considering putting the insulation on top of the roof boards.

  3. Richard – I have a log cabin and it is being used as a home gym with some equipment used (treadmill, rower, bike etc). Would you suggest using ventilation, as I bet this can create a sweaty environment once workout has been completed?

    • Any log cabin can benefit from vents, normally small ones are fine. I think if you leave a door or window open while you’re excercising it shouldn’t need a lot more.

  4. Hi Richard, Thanks for writing your info – it was very informative and I think I’ve got the idea but would you mind giving me your advice? I have a 4m x 5m cabin with a wood burning stove in it which is lit most days at the moment.
    I work in the cabin and things are getting a bit damp – papers etc. I was going to fit a simple opening vent low down near the fire but do you think it is worthwhile fitting another one higher up on the opposite wall? Feeling a bit clueless! 🙂

    • At this time of year you can get quite a bit of damp within a log cabin. Ideally you will have a damp proof membrane under the cabin which will help again much of this. But, as I’ve mentioned ventilation is equally very important. I would start with a vent low down across the log burner, centrally or the opposite side. This will help, if damp still persists then place another one opposite and higher up.

  5. Hi Richard, as always very insightful. I am in the process of building a Ben Clockhouse 9.3 x 4 cabin, I am putting a hot tub in the smaller room and was wondering if you think there is a benefit to fitting a mechanical ventilation system with heat recovery included. We will be using the cabin all year round.

    • I used to have a hot tub in a small log cabin and all I used to do was have a window and door open when we were using it. The cabin also had a vent and was treated inside. I didn’t find there was any need for anything else. I did though have a problem with the floorboards as my children would splash about getting a lot of water everywhere, this caused the board to expand and ripple. I eventually had to replace the floor and when I did so I nailed it tighter, left a slightly larger expansion gap between the boards and varnished it which helped. Getting back to the mechanical system I can see benefits of an extractor fan if you do not want the doors and windows open during use, anything more I think would be a bit of a waste of money.

  6. Hi Richard – great article. Found same marks on my cabin after removing some storage shelves. Will be treating and add vents. However, concerned that vents will lose heat whilst cabin is in use so need something I can open / close. Was wondering if any gadget existed that monitored, logged and reported humidity levels in cabins but thats perhaps is for another day…

      • thinking of getting either a dehumidifier that has humidstat built in or a bathroom vent with similar humidistat sensors. Believe these devices will come on when moisture goes over 60%. Motivation to do this over your original solution is as these rooms will need to be kept relatively warm in winters..

        • We’ve just moved into our log cabin, and I’ve noticed that things are getting damp, especially if left against the wall. Cabin is on pillars so loads of underneath ventilation. Wood burning stove is going a lot. Cabin was empty for a few months while build was going on, could moisture build up in the time it was empty? Outside not treated yet, was waiting for springtime. But will ventilation help under the stove?

          • It sounds as if the building itself is not ventilated as all the moisture you are creating is not being allowed to escape adequately. The stove would normally be ventilated as well.

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