Depth of Treatment and Moisture Content in Wood

I’ve spoken about the treatment of your log cabin in a previous post and I wanted to explain a little more about the importance of the depth of treatment which we recommend as 80 – 120 microns.

I personally try to make it very clear to customers the importance of a good treatment but I still find customers treating their cabin with rubbish and then contacting me a year later showing me splits and cracks, shrunk logs, uneven logs and other horrible things.

I tell them every time – All of this is entirely down to the treatment you are using and especially the depth and quality of treatment.

This post will give the technical aspects why we advise this, honestly I’m not making it up, there’s very good reasons for it:

Moisture Content, Sponges and the UK

I was sent this picture this week, The customer has had this cabin for about 9 months. The picture is showing a warped door on one of our Ingrid corner log cabins:

Warped door on an Ingrid log cabin

Warped door on an Ingrid log cabin. Notice the bolt at the bottom they have applied, this is the correct thing to do if you are experiencing a warp but the correct treatment could have helped prevent this warp.

I get a few of these problems over a year and 99% of the time it comes down to the treatment that has been used, and not just the treatment brand but the way it has been applied. I’ll come back to the warp in a little bit, let’s look a little more at the wood in this door.

Wood is a Sponge

Wood does of course warp and move, it can’t be helped, it’s natural and we all know that. The annoying thing with wood is that it acts like a sponge, you have to view every piece of wood in the Log Cabin as a sponge.

In a building there are shorter and longer logs – shorter and longer sponges. There doors and windows, horizontal and vertical parts to the frames, all of which are sponges.

Each one of these sponges is trying to be the same as it’s environment, I talk about this in my post on Splits and Cracks in Timber and how wood is constantly trying to reach an equilibrium with its surroundings.

If we zoom into a piece of wood you’ll see exactly why it’s a sponge:

Wood is a sponge and is made up of straws all drawing water for the tree.

Wood is a sponge and is made up of straws all drawing water for the tree.

Layer upon layer of straws are all drawing water for the tree. Many now support the Cohesion method theory where a tree draws it’s water using the tension of water, very clever stuff wood.

You can easily see from these pictures that when we look closely wood is full of holes and it’s these little buggers that will be causing a problem as they all fill with water or, drain of water as seeing as we killed the poor thing there is no tension of water to rely on.

For an untreated piece of wood this is happening constantly, it’s trying to reach the same moisture content as the surrounding air. This is known a Relative Humidity and is a measurement of the amount of moisture in the air around us.

Relative Humidity in UK

There is a direct link between the relative humidity and the moisture content in wood. The UK has an average high humidity of 92% and a low of 69% and this also depends on where you live.

Average humidity levels and these change according to where you are in the UK.

Average humidity levels and these change according to where you are in the UK.

Relative humidity change

Relative humidity changes over the course of a month can be quite dramatic in its highs and lows.

Relative Humidity in the months of the year in the UK

Relative Humidity in the months of the year in the UK

You can see from these that there is a difference in humidity. Over the course of a year it is 21% which is huge. You can also see how it is higher – wetter in the winter and lower – drier in the summer.

If you look at the graph of September you will see a difference of 18%. All of this is making wood grow and then contract, it’s happening constantly.

Moisture Content vs Relative Humidity

There is a direct correlation of the untreated woods moisture content and the humidity in the air:

There is a direct correlation of the amount of moisture in wood according to the relative humidity in the air.

There is a direct correlation of the amount of moisture in wood according to the relative humidity in the air.

Moisture Content of our Log Cabins

You’ll see from the charts above that at 75% relative humidity the moisture content of wood is 14%. The average is about 75% and this is why we dry all our log cabins to 14%.

It means that when we machine the wood it is at its ‘average’ moisture content for its lifetime in its intended location of use. To get it to this level of 14% takes about three days in a kiln.

By the way these things aren’t cheap to run either and they contribute to some of the cost of your log cabin.

You will see some manufacturers / suppliers happily tell you their log cabins are dried to 20%. I’ve seen a very high profile supplier happily state this in a promotional video as if it is a good thing!

Using these charts you can blatantly see that the relative humidity would need to be considerably higher to maintain the moisture content at that level and the UK would need a severe weather shift if that was to happen.

The supplier of course saves a day’s worth of money in the kilns but it means once the cabin is built it will shrink more to the UK’s average of 14%. This is why if you buy a log cabin and find loose joints as you install or a month or two later you see gaps appear, this is all down to the moisture content of the timber at the time of milling and that it is now reaching the UK’s relative humidity.

One of our 45mm show buildings I measured today. As expected the moisture content of the wood is 14% using my moisture metre. My meter is a very handy tool when finding out what is wrong with a customers log cabin, every time it’s treatment! Wood by its very nature cannot be ‘defective’ or ‘faulty’

14% – 16% Moisture Content in your Timber

So, understanding this, look for log cabins and indeed any other timber for use outside in the garden and make sure it has a kiln dried moisture content of between 14% and 16%. If it’s not at that then it soon will be and that maybe a problem as the joints will become looser.

If it is above this it will need to shrink further to reach this level which is the UK average.

This is also a very good question to ask any prospective supplier as it makes a large difference. You’ll see why in the next paragraph.

Movement in your Log Cabin due to untreated wood.

Here’s a startling statement and one that should explain it all in a few words:

For every 4 % change in relative humidity there is a change in the wood of 1%. 

Take a log of 114mm. Don’t treat it. Don’t treat it properly. Leave it out all year. for every 4% change it will grow or shrink 1.14mm.

We’ve already seen a difference of 21% in the UK. That’s about five 4% blocks of growths.

Would you believe that means a theoretical movement of 5.98mm for each log. In reality it’s about 3mm per log as wood can’t move that quickly but it’s still a bloomin’ lot.

Put that across 15 logs on top of each other and you have a theoretical movement of 89.78mm. WOW!

Understand that this is not a good thing, we don’t want your cabin or indeed your doors and windows moving to these degrees, if it does you can see various problems start to happen over time:

  • Warps in doors and windows
  • Cracks and Splits
  • Gaps may appear in some logs when they shrink quicker than a larger log.

Even though we use an average of 14% this can still be a problem as when relative humidity drops below 75% the logs will also follow it and shrink. If your logs have not been treated properly and if the drop is sudden you can see the smaller sponges lose their water quicker than the bigger sponges in your walls and you could see gaps appearing on the small logs.

It makes sense when you think of them as sponges that haven’t been inhibited and when you see the figures above it’s quite obvious why it’s happening and why the cabin is up and down like yoyo.

I did actually have a complaint a while ago that our logs were tight to get in whereas a neighbours cabin from a different supplier had fallen into place. This is why, if it’s a humid day the logs in a cabin will be very tight as they have swollen. A less humid days and they will be looser. But if you started with a log with a moisture content of 20% that then shrinks down to UK average 14% it will fall in to place, handy for when you are fitting.

Imagine what happens though when that same log shrinks down to say 10% moisture content during a scorching hot summer – yup, nice loose logs and gaps in the corners.

This is a 'print screen' from a promotional video of a prevalent supplier on the internet

This is a ‘print screen’ I took from a promotional video of a log cabin I watched on youtube,  you can clearly see gaps between the logs and this is down to the wood not being dried to 14% before milling. This supplier states they dry to 20% as if it’s a good thing. With further shrinking to the UK average of 14 – 16% the wood becomes smaller and you will see this. Some manufacturers will dry to 20% as it saves a days cost of the kiln.

Wind and Water Tight Connections

As well as this promotional video cabin having moisture content issues it also does not have ‘Wind and Water Tight Connections’ They’re the subject of this post: Wind and Watertight Connections in log cabins this is something we do as standard that others obviously do not do. Here’s a quick overview, you should be able to see the difference in the picture below. It’s a feature we don’t shout about too much. Having seen this ‘promotional video’ from a heavily advertised manufacturer perhaps we should!

Wind and water tight connection on our walls logs. With a moisture content of 14% - 16% and good connections and good treatment it's rare you'll have a problem.

Wind and water tight connection on our walls logs. With a moisture content of 14% – 16% and good connections with proper treatment your cabin will last for years and years. Not having a stepped W&W connection is not helping in sealing the cabin from the weather or helping to give allowance for further shrinkage. Creating the extra cuts to make this connection costs money and machinery and is a good place for a manufacturer to save it along with less time in the kilns.

Inhibit the movement of wood with a Good Quality Treatment

Now we know all this it is becoming crystal clear that we need to do something about it and that is where treatment is so important.

There’s all the bits about UV light protection, water repellent, fungicides etc which are all really good but the biggest thing a good treatment is doing is stopping this moisture transfer. It’s basically bunging up all the holes in the wood.

Getting back to the door at the start of this post. We had several conversations over this door and one of them was:

‘What did you treat it with?’ the answer was a very satisfactory Ronseal product which is known to be very good and one we recommend. The next question was:

‘How many layers did you give it?’ The answer was ‘two’

This is part of the problem, the manufacturer states three coats in their instructions and there’s a reason for that, they don’t just make it up, they know you need the proper depth of treatment for it to be properly effective and bung up the pesky holes in the wood and to stop any come back on them.

I pointed this out to my customer and suggested he needed to treat it as per Ronseals instructions and should have done so from the outset and that this could have probably stopped the warp. His reply was:

‘A third coat will be applied when i see fit’

This was missing the point completely!  If three coats is suggested on the tin then please use three coats from the outset otherwise it will not be functioning as it should and you can still expect problems.

If you don’t use the treatment correctly it is not the woods fault it has moved, it’s not the fault of the supplier or the fault of the treatment manufacturer. Putting it on nine months later or when ‘you see fit’ really isn’t going to help.

Depth of Timber Treatment on your Log Cabin

I’ve been playing with some of our show buildings today. Wrongly, this year we only put one coat of treatment on them as we just didn’t have time at the start of the season and now we are suffering as some of them are looking less than good and starting to show all the faults I warn customers against. A false economy and one we’ve got to now fix and treat them properly.

In a sense though it was a good exercise and  it showed some interesting results and is the inspiration for an experiment I am going to be running over the coming year for another post.

I went around the buildings with my meters:

Two types of meters for establishing what is happening with timber, a moisture meter and a depth of covering meter.

Two types of meters for establishing what is happening with timber and log cabins; A moisture meter and a depth of treatment meter.

First of all I calibrate it against a test piece. This meter measure the depth of a surface treatment in microns

First of all I calibrate it against several test pieces of various thicknesses to make sure it is functioning properly. This meter measures the depth of a surface treatment that has been applied to wood in microns. Like my moisture meter this one is also used a lot in fault finding with log cabins. Yup, every single time it comes down to the treatment used and applied affecting the wood.

Remember we’re looking for a depth of 80 – 120 microns as I have mentioned in the Log Cabin Treatment post which is the equivalent of two to three coats of a high quality treatment. This is to fully ensure the treatment is going to be effective in inhibiting the constant transfer of moisture and to bung up all those holes in our wood making it a little less sponge like.

A reading of 72 microns.

A reading of 72 microns.

Only one coat and this one was using one of our stains. With just one coat this attained 72 microns, with two coats it would be pretty much there. Be aware though that it does vary according to the painters skills in keeping an even coat.

A reading of 55 microns

A reading of 55 microns

This one was interesting for me and confirmed what I knew in that clear or close to clear treatments cannot give the same depth of coverage in one go, this would take three coats to be effective.

This building is a shepherd hut we have on display using one of our paints. Still only one coat but done by a professional painter so it’s quite uniform and he applied it quite thick. Another coat is still needed but only just. Still not a bad coverage at 85 microns.

This last building really surprised me, it’s a bespoke 58mm log cabin that was made to fit an area, it’s been up for years and we used to use it as an office for some staff. We painted this with a treatment obtained locally, I know for a fact it has had four coats on it over it’s life of about 10 years as I painted two coats myself.


This building has had four coats (of a treatment we don’t recommend), I was really surprised at the depth!

And the treatment that we used? Yup something cheap! We’ve still got the tin. If you visit our show site ask us about this cabin, it’s the big old one at the end.

Here’s another measurement at the door, slightly thicker but still very much down from where we need it to be.

Virtually the same depth on the door as well.

Virtually the same depth on the door as well.

I was actually quite shocked at the difference in the depth across the treatments. This one I know was one of the cheaper treatments you can get. Some of the really cheap ones will barely register on this meter and form playing in the past you’d need to apply 8 – 10 coats to get to the 80 – 120 microns needed. With this cabin we do have all the features that we don’t want, I’ll do a post dedicated to this cabin one day.

Keep an eye out for my experiment post where I am going to paint lots logs in lots of different treatments from various manufacturers and various coats applied. I’m then going to monitor and measure them over the course of a year for moisture content and expansion / contraction to prove all of this more.

It’s worth knowing that when you pay for a treatment much of the cost of it is for the depth of the application.

So, my advice is:

Buy a top quality treatment and follow exactly what it say on the tin to get a proper depth so it can do it’s thing. Don’t only put on two if it asks for three!

Just to finish, a customer will tell me ‘But I used it on my shed and it was fine’ A shed and a log cabin are two entirely different animals. A shed is held together by a frame and the cladding will be about 12mm. It does not behave at all the same as a slotted wall log which is not held at all.

Here’s a good example of a sponge in action with only one layer of a poor treatment:

Smaller logs shrinking quickly by the side of a window far quicker than the large ones elsewhere in the cabin.

Smaller logs shrinking quickly by the side of a window far quicker than the large ones elsewhere in the cabin will leave a gap. When all the others have shrunk to the same moisture content this gap then closes. It’s best though if we can inhibit this by properly treating the cabin with a good treatment and the proper depth from the outset. We really don’t want this happening!

This cabin only had one coat, the customer told me it was fine for his shed:

Fine for a shed perhaps but a shed is held together with nails on a timber frame with a thickness of about 12mm. A 45mm lump of wood is a bit different. Even so, notice the contraction of the boards, is it really fine for a shed as well,? Perhaps you should follow the same rules for all your garden timber as all of it is behaving in exactly the same way.

Also, all of the above applies whether a building is tanalised or not. All tanalised buildings behave in exactly the same way as an untreated one and STILL require all of the above.

Moisture Difference in the outside to the inside of a Log Cabin

For a future post I’m going to be showing one of our neglected show buildings, and whether a log cabin should be treated inside, after seeing these readings and for this specific building the answer is yes for several reasons.

This moisture content reading I showed you earlier of the 45mm building was 14%, this was an external reading of a log. Looking at the same log internally it is showing a very surprising 9% moisture content! This is due to it being sealed up most of the time, no ventilation, no damp proof membrane in the base and in constant sunlight with high temperatures inside compared to the outside.

Big heat build up inside an unventilated log cabin means the moisture content has dropped to 9%

Big heat build up inside an unventilated log cabin means the moisture content has dropped to 9% this cabin is a show building and has not been treated on the inside. It is un-vented and in direct heat all day with no damp proof membrane in the base or a timber floor.

This is why sometimes you can see a split in a wall log open up, the poor thing is bigger on the outside than the inside. We need to treat the inside of this cabin as well!

I think this explains it well so please also consider treating inside your cabin if some of the above conditions exist so the entire log is regulated and inhibited.

Further advise on Log Cabin Ventilation.

Please also see my other advice post on the Treatment of your Log Cabin which has other information you may well be interested in.

This post also forms part of my timber series which is still being completed:

  1. Types of Timber in your log cabin
  2. How we can cut a timber log to make a cheap log cabin.
  3. Moisture content in timber, machining and the impact of the content.
  4. Timber calculation to cut costs you can work out yourself and see where you maybe opting for a bargain while adding to a companies profits.
  5. More expansion information for log cabins.
  6. The pitfalls of thinner logs, barge-boards, windows and doors.
  7. Drying processes – kiln dried versus natural drying.

Types of Timber in your Log Cabin

I have been emailing with a potential customer today and he asked me this:

“I am still therefore split in my decision between your cabin and one other competitor, (an improvement on the eight I started with!).  To this end, can you tell me the real issue over the timber quality with Companies that are using mixed pine/spruce as opposed to your materials?  The other Company do this which seems to be the main difference as neither of you do finger jointing. Hopefully then I can make a better informed decision.”

I explained in a very condensed version what the differences of timber are that are currently being used in log cabins across the industry but mainly in the UK. I think it was actually a bit of a ramble but with a glass of wine in my hand I can write it a little better here and more concisely than what was sent my customer earlier today by me.

If you are researching a log cabin it helps to know what you are getting, and like my customer asked, you can then make a fully informed decision:

Two Types of Timber we can use in a log cabin.

In a log cabin we can either use Pine or Spruce.

1. Pine – Wikipedia Pine Entry

Pine is known as a redwood, it’s widely used for a lot of things we use daily. No doubt you will have some pine furniture at home.

Pine isn’t as dense as Spruce and therefore it does absorb water quicker. It’s the cheaper of the two types we can use in a log cabin. We use it very widely in the garden for fencing, posts, furniture, play equipment etc.

Because it is less dense, we will pressure treat it to guard against rotting in the long term. It also tends to have looser knots and more of them, it changes colour with sun light to a darker colour. It’s also not as structurally strong as spruce and has wider ring growth.

Pine tree

Pine tree

2. Spruce – Wikipedia Spruce Entry

Spruce is a white-wood, it doesn’t discolour any where near as much as pine so it is more aesthetically pleasing inside a log cabin.  It is more dense than pine as well, the knots are tighter and usually there are less of them than in pine. It is structurally stronger but is more expensive than pine. Tuindeco log cabins are entirely spruce including the roofs and floors.

Spruce tree.

Spruce tree.


The main difference between the two is the denseness of the timber and this makes a lot of difference in a log cabin. Because of this it stands to reason that they both behave differently and this is where the problem starts when we mix timbers.

I’m sure you’re aware of a Bi-metal strip that’s used in thermostats?  With this we take advantage of the different expansion and contraction properties of brass and copper, both of which are similar metals like spruce and pine are similar.  But, there is of course a difference between them.

With a log cabin do we really want to have different rates of expansion?

If we do have a mix It will mean that logs expand and contract at different rates, gaps can appear, splits and all sorts of horrible things could possibly happen over its life if we are not fully aware of it.

We also have the aesthetics of it, lovely white spruce contrasted with the red of the pine really doesn’t look very nice. We then also have to contend with pine’s tendency to rot quicker unless it has been pressure treated.

Some suppliers will also specify finger joints using a spruce / pine mix and then we have even more issues with different rates of expansion. It does make for a far cheaper log cabin though and we can still overcome it by remembering it and when we are building it.

Varying expansion rates is great for a Bi-metal strip, not so good in a log cabin unless you are aware!

Spruce / Pine Mix

So, it’s really not a good idea to make a log cabin from pine in my opinion and certainly that of Tuindeo if you find a cabin made of pine it’s not a good thing, but, if you do take it, it should be VERY cheap.

Of course some companies will do it as it saves a lot of money but please check what is being used and that the cost savings they have are properly passed on to you.

Far more popular though in the UK, thankfully, is adding a cheeky spruce / pine mix into a log cabin, it saves the supplier a LOT of money and should hopefully save you as a consumer as well.

Lots of mixes are out there and only really accepted in the UK,  mixes are not tolerated in Europe, I think they are better educated than here in this respect.

Please consider that you may have the following problems in the long term with a mix:

  • Different rates of expansion may cause splits, warps, gaps and long term problems.
  • Pine is less dense and absorbs more water than Spruce so make sure you treat it very well.
  • Pine is redder than Spruce and not as attractive inside your log cabin.
  • Knots are looser in pine, there are generally more of them and they are more likely to fall out so before you apply your treatment I would recommend ‘knotting’ the logs first before you treat them.

If you do have a log cabin that has a mix, when you install it try to keep the above in mind and grade your timbers remembering the expansion rates, try to keep it even. Also if you have mixed timber and finger joints try to stagger your logs and remember the expansion will make a difference to longevity and this needs to be thought about as you build and treat it to make it last as long as one would expect.

Timber Series

Following on from this I intend to write a short series on timber in log cabins, you really wouldn’t believe the differences and the ways we can play with wood to get to the prices you the consumer wants but, do you really want it in the long term?

The following will be added to this blog over time:

  1. How we can cut a timber log to make a cheap log cabin.
  2. Moisture content in timber, machining and the impact of the content.
  3. Timber calculation to cut costs you can work out yourself and see where you maybe opting for a bargain while adding to a companies profits.
  4. More expansion information for log cabins.
  5. The pitfalls of thinner logs, barge-boards, windows and doors.
  6. Drying processes – kiln dried versus natural drying.

Here’s an old post I wrote on how to get to a cheap log cabin, in the new series I will show you more, you wouldn’t believe it. A timber log in a log cabin is not always just a timber log, there can be HUGE differences and all of these comes down to prices for the consumer or of course the company profits.

Oh, also watch out for spruce in the logs and pine in the roof and floor. It doesn’t make a great deal of difference but it’s nice to know what you are getting for your money!

Log Cabin Treatment Panic

You’ve got your brand new log cabin.  It’s up and it’s chucking it down, it’s January with record rainfall, floods everywhere and your poor log cabin is bare wood, soaked, you’ve got to treat it haven’t you? – PANIC!

NO you haven’t.  There is no panic whatsoever!  So wait a little while, relax, stop worrying about her, she’ll be fine for years – sort of!

This log cabin belongs to a friend of mine I supplied from Tuindeco years ago, apparently, after 12 years she’s still deciding on the right colour!  Girls!

Look at the state of the poor old thing, very neglected and unloved it would seem but it’s home to chickens on the veranda and guinea pigs inside during the winter and very much loved and used so she tells me.

I do despair, just look at it!  But the point of this is that it is not rotting and it’s still a very solid untreated log cabin.

A log cabin that has never been treated in it's twelve year life span.

A log cabin that has never been treated in it’s twelve year life span.

I’ve asked her to keep leaving the choice of colour until later just so I can see what happens, I hope to post again in ten years when it’s still standing and knowing her she’ll still be pondering the right colour!

Yes the poor ol’ thing has her problems.  You can see in this picture how dry the timber is, it’s cracking and shrinking.  These pictures were taken last summer so she will look different now.  See a post on cracking and splitting in timber for a little more insight into what is going on with timber cracks.

Cracking and splitting of log cabin logs

Cracking and splitting of log cabin logs

She’s got one or two more problems as well.  Nothing insurmountable though, for instance, this log cabin has a few friends:

This log cabin is suffering with mould and fungus.

This log cabin is suffering with mould and fungus.

Yup, it does have a little fungus on it.  It’s not dry rot as it is way below a moisture content of 20% and never at a steady temperature of 23 degrees which both conditions needs to exist for dry rot to occur.  It’s just good friends and they like each other, no harm done.

Here’s another friend:

Another friend attaching itself to an old log cabin

Another friend attaching itself to an old log cabin

The back wall of this log cabin is covered by a hedge, it’s never been cut and now Ivy is growing over it.  Goodness know’s the out come of this but the old girl is still going strong and fully in-contact with a hedge and all sorts of undergrowth.

Overall though she’s jolly good.  For a log cabin of this age, no treatment ever, she’s still solid and displays no rot at all.  Here’s the doors and Roof Purlins:

Untreated purlins on a very old log cabin

Untreated purlins on a very old log cabin

Untreated doors on a log cabin

Untreated doors on a log cabin, they have warped a bit as have the windows which don’t open but not too bad.

We give a ten year guarantee on our logs cabins against rot. There’s conditions and they have to be treated regularly blah, blah.  If it was up to me I’d give a twenty year one and no treatment.  It’s impossible for timber to rot!

Ok, maybe that’s a stupid thing to say, I’ll add a note to it:  It’s impossible for timber to rot as long as it is always VENTILATED and allowed to DRY.

So I reckon our guarantee is safe.  If you get any rot in 20 years time please let me know and I’ll pay for your replacement out of my own wages.  It won’t happen though if she’s allowed to breathe, and, that’s the key with all timber products – ventilation.  If it gets wet and it’s allowed to dry out it will NEVER ROT and that’s an inherent property of timber.  Not just ours but any timber providing it is timber of a suitable quality for it’s intended use, especially for log cabins watch out for where the timber comes from, slow gown, cold climate etc.

Walter Segal

Just a quick note, I’m a fan of this chap. He’s done a lot for home building and one of his principles was that of timber ventilation with buildings on stilts.  If timber is ventilated it will never rot. It’s why I love timber frames as bases for log cabins and I’ve been involved with lots of log cabins on stilts and similar construction methods they all work and never have I had a customer complain of rot.

Log Cabin and Timber Treatment

Of course with all my above whittering and pictures I am not AT ALL advocating not treating your log cabin or any garden timber.  It needs it!  And you must treat it at some point, the sooner the better. We’re not actually treating it just to prevent rot we’re treating it for lots of other things.

All I’m saying is don’t worry or panic over it, you do have time to do it without worrying if you can’t do it straight way.

If you don’t treat your log cabin or timber you can have a few problems and rot is not one of them

  • Discolouration of the timber.  See the pictures above, she doesn’t look that great.
  • Warping and shrinkage of timber.  The timber will dry out, warp, distort and will allow the ingress of water either through seams of via moisture transfer and may be pushed out of shape. Doors and windows may well warp and splits may well appear.
  • Expansion, the bloomin’ thing wants to reach an equilibrium with it’s surroundings, it wants the same moisture content that is in the atmosphere. So when it’s moist it wants to be moist as well.  We can’t have that! The thing is up and down like a yoyo if we let it.  Each of part of the timber should be viewed as a sponge, each piece is absorbing and expelling water. We need to to stop behaving like a sponge really. See this article for more on Moisture Content
  • As well as the above external pictures, internally, water marks could become visible which is unsightly and can develop damp spores especially if internally it is not ventilated.  Pay attention to this if you are installing a hot tub. The Log Cabin pictured above is always ventilated for the guinea pigs sake and another reason that even though she is not treated she’s still going strong and NOT rotting.  This log cabin has a constant flow of fresh air. See this article for advise on Ventilation
  • This log cabin is fortunate but insects can attack timber and a good treatment will stop this.
  • Attack by UV light causing drying and further splitting.  This log cabin is relatively shaded from it with hedges and trees all around, yours may not be.
  • Filthy!  Yup, she’s a dirty girl, inside and out and this is not something we really want with our very expensive log cabin.
  • Weather ingress. Even though it may not rot it will still soak up water and this will percolate through to the inside especially at the corners, doors and windows in an exposed environment.

So, what if it is weeks before you treat your log cabin?

You can’t treat it straight away?  What’s the worst that can happen?

Dirty wall logs on the log cabin

Dirty wall logs on the log cabin

Yup, the poor log cabin gets filthy with rain muck thrown up all over it.  When, and if this happens all you need to do is use a pressure washer or a good jet attached to a hose pipe, it comes up like new – honest.

Also, if you find darker marks on it which are a damp fungus forming all you need to do is apply a dilute bleach solution and it will all go and bring the timber back to normal ready for treatment. This will often happen if you’ve left a cabin out in the rain and covered it with plastic while waiting to install it for a month or two.  The humidity created is great for a fungus but it’s very easy to remove with a bleach spray and then a wash.  Our Sauna display cabin had this after being stacked outside for months, a quick spray and a wash and it’s all gone.

Pressure Washer

Just staying on a pressure washer:  I’ve installed log cabins in tempest, storms, gales, snow,hail, in fact every weather condition imaginable.  You can’t help to get it dirty inside and out sometimes especially big installs.  Just before you hand over to a customer (or yourself) give it a good jet wash or hose down, it’s like new regardless of how messy you’ve made it during the installation.

Water ingress

Timber won’t rot if it’s not treated but it will let in and soak up water by way of moisture transference.  This is regardless whether it has been tanalised or not. Even a tanalised log cabin still needs full weatherproof treatment other wise it will still behave in the same way.

To stop ingress and absorption by transference we must treat it.

Did you know on average a wall log which is untreated will move by up to 3mm over the course of the year as it absorbs and then expels moisture.

If You don’t treat it at all.

If we don’t treat it as well as it getting dirty (least of our problems) we can also have other problems as the logs, doors and windows will expand and contract due to moisture transfer happening too rapidly causing the timber to expanding and contract too quickly. It may also cause warps in doors and windows and splits. This article explains this a lot more – Moisture Content in Log Cabins and Wood.

Purpose of a log cabin timber treatment.

I’ve said what happens if we don’t treat a log cabin and that it really is a good idea. So now we are committed to doing it what are we looking for in a treatment?

  • UV protection – we need to protect it from the sun, and the sun and it’s light is a bugger, it’ll dry out timber, cause cracking, distortion and lots more, it’s a real bugger for wood.
  • Weather proofing.  Wood loves water, it soaks it up, it wants it, it’s a property but we’re meanies and need to keep it at steady 14%. We try to protect it from absorbing water. We try to protect the joints and stopping any water marks from coming through. This is also very important for the doors and windows. If we allow it to soak in water above 20% it will start to rot.
  • Reaching an Equilibrium … the bloomin’ thing keeps trying, see this post: Cracking and Splitting in timber.  We really don’t want this with our log cabin.  Stopping this will save us a lot of time and will make it last for years.  Stop the equilibrium I say! Moisture Content in Wood
  • Creature proofing … Pesky creatures, fungi, worms,etc.  A good treatment will stop the pesky critters.
  • Elasticity – As I’ve said the thing is moving a lot, even with a good treatment stopping the absorption and shedding of moisture, we need a treatment that can cope with this so high elasticity in also important.

What timber treatment should we use for our Log Cabin?

Hm, now this bit can be a hotbed of law suits.  Firstly anything expensive, we only recommend Sikkens, Kingfisher, Sadolins or our own European brands shown in our website or brochure such as Koopmans, Embadeco or Embalan and more recently the super treatment from Valvoline Max-Release Protectant – now known as ‘Carefree Protectant’ which is heralded as a revolution in timber treatment and from what I’ve seen the stuff is amazing

If it’s a cheap treatment we don’t recommend it especially ones designed for sheds or fences or which can be sprayed on.

Please don’t be tempted to use anything cheap! Any complaints we have had with cracking timber or mould algae, excessive shrinkage etc have always been found to be caused by a cheap treatment, use at your peril but we will not offer any guarantee if you have used it, I can always tell as well!

Please do NOT use a cheap treatment, all the problems that have been reported with a log cabin can often be traced back to this.

Expensive is the way forward, you get what you pay for and it’s certainly pertinent when regards to treatment. If you use treatment beginning with the third letter of the alphabet and only given it two coats and then complain in a few months time that you have splits I will tell you to apply five more coats of the same treatment or treat it again with something expensive.

If I was to get technical we need a depth of treatment of between 80 and 120 microns. This is the equivalent to two to three coats of an expensive treatment. To accomplish the same depth with a cheap one may take up to 10 coats and this is where the problem comes when customers use a cheaper treatment and give it two coats, you may as well not bother. It’s good on a shed perhaps but no good at all on a log cabin as we need to inhibit its movement. Anything less than 80 microns is not going to do anything.

When asking a treatment supplier always specify it’s for “Planned, smooth Spruce” and let them advise you on the best treatment for that style of timber.  Rough sawn treatment is not all compatible.

A great source of advice is Brewers, they’re a professional trade paint supplier and may have other ideas and I’ll always agree with them, they are the people who know treatments! Most of the time they will recommend two undercoats of preservative with two top coats of Sikkens.

My old log cabin was painted 15 years ago with Sikkens, all I do is give it a quick wash each year and that’s it, I do recommend it.

But, we have this new stuff:  CareFree Protectant.

It can dry in 15 minutes, be painted on wet, it’s clear and still provides UV protection.

I’ve even seen it coat grains of sugar in a glass of water and the sugar didn’t dissolve! Clever stuff and now I’ve used it it is amazing, I even tried painting it on wet timber in the rain and all the water wicked away as I was painting (I’m not going to formally recommend painting in the rain though).  Amazing! We’re now using this on everything on the show site including Larch and Hardwood furniture / fencing.

CareFree Protectant the new name for MaxRelease Protectant:

With our changing weather conditions our wood / concrete gets a lot to endure rain , sun, wind and frost . To keep your wood / concrete in optimum condition MaxRelease has developed the best protection . The water-borne coatings without organic solvent penetrates into the wood / concrete and thus provides a protective layer against moisture, sunlight , wind and rain for all types of wood and wood products , such as fences , decking , garden furniture , garden poles , log cabins , gazebos , larch and hardwoods , and concrete products such as garden poles and fence systems . It forms a thin layer on the substrate , so that the structure of the wood and the concrete remains pretty visible.

Benefits of Carefree Protectant :

  • Long-term protection against moisture
  • Low maintenance
  • Easy to apply and easy to clean
  • Excellent colour stability with minimal fading due to sunlight
  • Less fungal and algae
  • Impregnating
  • Corrosion resistant
  • Water resistant
  • Inhibits the natural transfer of moisture
  • Prevents kalkuitbloei in concrete

CareFree Wood Protectant is easy to use . Wood Protectant is a quick-drying material and will dry within 15 minutes ( depending on temperature , humidity, type of substrate ) . There is no primer or other type of primer is not necessary in order to bring . To Wood Protectant This makes the long-term protection of wood and concrete in a simple and quick job . MaxRelease Wood Protectant must be stored frost-free.

Having used this extensively now, I really do recommend it!

Damp Conditions

Regardless what log cabin you buy, from us or anyone the Carefree is excellent and one of its properties is protection against humidity.

Now this is clever stuff, it’s water soluble and goes on really well.  It will stop the formation of damp spores and is highly recommended for the inside of a log cabin if it is shut up for months on end or subjected to a damp atmosphere.

Just quickly note on hot tubs, Log Cabins are great as a hot tub enclosure but make sure you use a vent, this also applies if you are storing lots of damp tools.

Carefree Protectant Timber Treatment

When do I treat my Log Cabin?

Now this is something I’m asked all of the time.  My stock ‘official’ answer as within the brochure and literature is “Always paint / stain / treat your cabin BEFORE installation”

But, oh my goodness that is a real pain, you get paint in the grooves, on the corners and joints, it’s harder to install.  You get sticky patches that then get sticky on your fingers, that then leave finger marks on the inside of the logs.  It’s a nightmare!

So you’ve had the official answer, the unofficial and my opinion only is just build the cabin and paint it later. In all the years I’ve been doing this I haven’t had a comeback.

One hint I would give though is when you come to paint it, remove the top of the door and window fascias and paint behind them, otherwise when it expands, as it will in winter months, you’ll be left with a white line that’ll need painting again.  It will never match up so always do it first and beat the sneaky blighter creeping up on you with the annoying equilibrium thing timber does.

How much do I need?

Another question I’m always asked and this one is tricky.  It’s all down to the coverage recommended by your chosen brand.  But for instance our stain covers 14 – 15 sq.m and the the paint covers 5-8 sq.m. It does vary on the type and brand of paint or stain your are using.  It’s best to work out the log cabins dimensions and calculate it and then give this measurement to your supplier, or do what I do and guess and if you run out get some more.


I’ve had customers ask about treating the roof. My answer is always why bother? If the final roof covering is applied properly there really is no need.

Summary of wood treatment for Log Cabins

So, in summary what have I said:

  • Don’t panic over getting treatment on your log cabin if it’s wet or raining when you unpack and install your cabin.
  • You have a little while before you need to worry, especially if you have a pressure washer or a jet hose so you can keep in clean
  • You do NEED to treat it to make sure it lasts and helps to inhibit the transfer of moisture.
  • Clean it with a bleach solution for spores or a jet of water for dirt.
  • ALWAYS keep it well ventilated.  Ventilation and allowing timber to dry if wet stops all Rot. Here is further information on Ventilation in a log cabin
  • ONLY use an expensive treatment so you know that you will be getting a depth of at least 80 microns.  The more expensive it is, the deeper it will be and the longer your log cabin will last and more importantly, if you’re lazy like me, you probably will not need to do it again for a good while. Do NOT use the lower end of the market to treat your log cabin I guarantee you will have problems as they do not inhibit the transfer of moisture which is important with log cabins. Please see this article for more on Moisture and inhibiting it in wood.
  • Watch out for the natural equilibrium of timber, inhibit this with a good treatment and make sure it is high in elasticity.
  • Follow the manufacturer’s advice. If it says three coats give it three coats. It is all about the depth attainable of the final finish.

Depth of Treatment and Moisture

Please see another post on the depth of timber treatment and the correct moisture content for log cabins.

Please see another post on the depth of timber treatment and the correct moisture content for log cabins.

More information on the Depths of Treatment and Moisture content of your Log Cabin

One final note, customers will often leave their cabin install until the ‘weather is better’ or look for a ‘weather window’. In my opinion it is always better to get it up and worry about treatment later, don’t let a bit of rain put you off!

The joy of a log cabin install in the wet. I remember this morning, we had to remove a layer of snow off the roof and then it rained all day while trying to install the insulation and roof shingles.

The joy of a log cabin install in the wet. I remember this morning, we had to remove a layer of snow off the roof and then it rained all day while trying to install the insulation and roof shingles. You too can have this much fun installing your cabin in the wet.

I have written another post on Treatment following a customer’s question that needed a little more advice: Treatment of a log cabin – A Customer’s Question you may find this interesting.

Please also see another post: Log Cabin Treatment Gone Wrong

If you leave it a little too long to treat your Log Cabin or it is starting to get dirty, this article may help you: Cleaning a Log Cabin

This post relates entirely to the Tuin range of Log Cabin Treatments and clarifies what and how we recommend they are used if you choose to use our range.

Pressure Treated or Tanalised Log Cabin

These two terms are used a lot in the garden industry.  Timber is often described as ‘tanalised’ or ‘pressure treated’.  Options are given with garden buildings, including our log cabins for them to be tanalised, others give them options of pressure treatment.


The two terms used are describing exactly the same timber treatment:

  • Tanalised is actually a trademark, as is ‘Tanalith E’ which you will see sometimes.  These brands have been around since the 1940’s.
  • Pressure treatmentt is the process carried out using ‘Tanalith E’ or similar.


The treatment process is carried out by placing the timber in a big tank.  The door is shut and a vacuum is created inside it.  Then the pressure treatment fluid is allowed to enter and is forced in the wood under the pressure.  It penetrates to a depth of a few millimeters.

Pressure Treatment process using 'tanalith' or similar

Pressure Treatment process using ‘tanalith’ or similar


The main ingredient is copper with other chemicals added.  Copper is excellent for protection against rot and insects.  The other chemicals (Biocides) protect against other rot that the copper can’t such as ‘brown rot fungi’.  These substances are not harmful at all and can be used around animals and children.  Fish may be sensitive to it.

Rot Proofing of Timber 

It does exactly what it says and protects the timber from rot really well, internally they say about 60 years and externally about 30 years against any form of rot.  It’s pretty good stuff!

Limitations with Log Cabins

For the treatment of rot there is no real limitations, it works and works really well.  The main problem with pressure treatment of our log cabins is:

  • It is NOT a weatherproof treatment

You can of course not bother treating it, the cabin is not going to rot, well, not for thirty years or so but because it is not a weatherproof treatment you can expect the logs to absorb water which will result in rings and marks just like your coffee table at home with a hot mug of hot chocolate.

  •  It will discolour, it fades to a honey brown and eventually to a silvery grey.

Overtime it will discolour.  We can pressure treat / tanalise your log cabin in green or brown but the same appearance will result.  Normally over about five years.

This cabin was provided with Green pressure treatment:

Green Pressure Treated Log Cabin

Green Pressure Treated Log Cabin featuring the Sten Log Cabin

This one is done in brown tanalised pressure treatment:

Brown pressure treated log cabin

Brown pressure treated log cabin Featuring the Halvar Log Cabin

There isn’t a great deal between them but both will end up looking the same in a few years.

  • All of the wood is treated.

And this may be a problem for you.  When the logs are put into the vacuum tank there is no way to cover one side, all of it gets treated so what you see on the outside is what you see on the inside.


If Holland read what I’m about to say I may well get ‘questioned’ on it, but, I really hate pressure treated log cabins.  I try and steer my customers away from it.

In my mind as it’s not weather proofed you will still have to give your cabin a proper treatment, preferably with something expensive so you rarely have to repeat it.  If you want it to stay looking good you have to treat it.

Most people love the bright airiness of the cabin, do you really want to be staring at green or brown walls and ceiling, we go out of our way to source white wood over red wood so you have exactly that, an almost white interior, to spoil it with tanalisation just isn’t on really.

However, with that being said, other customers I will positively encourage such as this one:

Tanalised Log Cabin Garage

Tanalised Log Cabin Garage

Now here is a prime example when tanalisation / pressure treatment is excellent, it has a damp car stuck in it, it’s open to the elements internally.  Rot treatment makes sense! Here’s another one when I strongly recommend it:

Highly recommended to pressure treat this log cabin

Highly recommended to pressure treat this log cabin

Another prime example, I’d suggest to this customer to pressure treat the log cabin.  It’s constantly open to the elements internally and externally.  It makes sense.

All my other cabins, hmm, I don’t think it’s necessary, you’ve got to treat it anyway so why not put the money you would have spent on tanalisation into your treatment such as Sadolin, Sikkens or our excellent range of log cabin Paints and Log Cabin Stains designed for smooth planed pine wall logs.

I think it’s a bit like marmite, love it or hate it ….. up to you!