Log Cabin Contraction

This post follows on from Mr Currie’s comments on my previous post about Contraction in Log Cabins

Mr Currie commented on my post:

“I installed a log cabin from another company in 2008 and within 6 months a gap appeared between the logs next to the door frame, which I now think might be due to a design flaw. The optional front veranda is not integral to the log cabin – the ‘veranda kit’ supplied solid battens to attach it directly to the bottom six logs on each side of the cabin using screws. This is in effect attaching several of the bottom logs together, and I guess that this probably restricted the ability of the logs to expand and contract with the ones above them. I’m now wondering if I detach the battens whether the gap might disappear as the wood ‘settles back into place’.”

I very often help people via my blog who have bought elsewhere and have run into problems with their Log Cabin for whatever reasons. Normally it’s the ‘run out of guarantee’ ploy or just a lack of knowledge from the retailer that brings all sorts of people to the blogs and I really do enjoy helping where I can.

You’ll find Mr C’s and my conversation carried on in comments and we then went to emails, several were exchanged as well as pictures. Here’s a selection in case you are having the same problem

Log Cabin Contraction Problem

This was the problem:

Gap

A gap appeared after 6 months with a log cabin Mr C bought in 2008 (Not From Us), he’s lived with it ever since.

awfw

He had identified after reading my blogs that the above really shouldn’t be done as the screws in this cover plate show that all the logs are being restricted. From previous articles you will have seen why this is a NO NO.

Mr Currie thought this maybe what’s causing the gap at the top of the doors and certainly while this is not good or a correct way to install the cabin in the first place.  This isn’t though the culprit for the gaps by his door.

I do occasionally have a moan about “qualified carpenters and joiners” building log cabins which makes me shudder when customers mention this when a problem occurs.

The previous advice Mr C had received made me chuckle and also makes me shudder, yes I see and hear this sort of thing all of the time – Beware the qualified Carpenter!

“A friend of mine who has been a ‘time served chippy’ for 40 years told me that all I had to do was nail a board over the gap. It’s amazing how people who have worked with wood for so long can have such a total misconception about it’s properties and how it behaves in a structure like a log cabin. I’m sure that’s a familiar story to you :-)”

Assessment Based on the Log Cabin pictures received

I sent Mr C my assessment of the problem as below, this may also help you if you have a similar problem with your log cabin:

Dear Mr Currie,

Thank you for these pictures and description. It made me chuckle you mentioning a time served carpenter!

Professional Carpenters, Joiners and worse still Builders are the scourge of my job, whenever I have a problem with a customer it is always when one of these groups of people have had something to do with it!

Looking at your building I think you can fix this quite easily.

Depending on what you have treated it with will make a difference to how much it expands and contracts. During the first year though we see this the most as the wood is still alive, in effect the straws that make up the timber is still wide open and is sucking in and blowing out moisture meaning it expands and contracts sometimes quite wildly.

A good treatment and wood dieing a little more over the first year or two will see this reduce, it does still happen though.

This is what happened in your first year. The moisture content has dropped, the straws have now closed up more and over the years she’s reached a level. I would imagine this does close up a bit over the Autumn and winter though when moisture returns to the wood from the surrounding moist air?

To solve this please remove the fascia on the inside of the door. I bet the top log is touching the top of the door frame.

Check under the door frame for any chocks, also check to see if they put the floor under the frame, this often happens and lifts the frame. Sometimes when we’re installing in the winter months a new cabin we do have to chock the door slightly as the gap is too large. Please let me know what you find.

Please also check the top of the window, there maybe an expansion gap issue there as well?

Regarding your veranda, it really shouldn’t be screwed together like that, your solution will work provided the screws are not done up too tight, you could also make something like the attached which will hold the logs without any fixings, you may need to move the veranda forward slightly.

Best regards, Richard.

Mr C’s Reply following my Assessment

I have to be honest that I have never actually noticed if the gap closes up much over winter, mainly because it has been used as storage but is now being converted over to a workshop. It has not had much treatment to be honest, it had two coats of Cuprinol after it was built and another coat of the same last year.
I removed the top left and right part of the fascia on the inside of the door, and you were right about the top log touching the top of the door frame. When I removed the bottom part of the fascia there was an almighty cracking sound, and now the door frame is a little looser. I think that the bottom part of the fascia was resting on the floor…
Anyway, I’ve attached some photos of the door with the inside fascia totally removed. Interestingly I can’t get the bottom part of the fascia back on now – as you can see the door frame must have dropped by a few millimeters when I took it off
aew

You will notice the the wall logs have contracted and are sitting directly on top of the door frame

Here you can see the gap at the top, the logs cannot concertina down any more than they have, hence why a gap if forming.

Here you can see the gap at the top, the logs cannot concertina down any more than they have, hence why a gap if forming.

Doo

The bottom door fascia was actually holding the whole front of the cabin up as the door frame has now dropped and cannot be fitted again. The Fascia does seem to be rather wide.

Solving the Log Cabin Problem

Having seen these pictures and following emails my advice to Mr C was:

I’m pleased to see this is as expected, the bottom fascia looks to be rather deep and will have been holding the cabin up.
At this point, if possible I would not plane the door frame as this may weaken the frame, plus you will have to contend with the screws. I would take the door frame completely out, this will then let the cabin settle down and the gaps should close up either side.
If you have a jigsaw for ease or a handsaw if you are feeling strong I would then take a notch out of the top log. I’ve attached a picture that shows a top log with a notch. I think about 10mm would be enough above the door frame. This will then give the log room to contract further in the height of summer. This time of the year though she will be very slightly bigger than she was in August.
The bottom of the door fascia does look big, you will also need to trim this down.
Doing this and putting the door back in with the fascia should solve this problem for you.

Contraction and Expansion

The problem Mr C had isn’t really one of design as this can sometimes happen no matter the design of the log cabin, this picture shows a notched log above the door which is done on some models we do if the calculations and size of the door requires it.  This is the picture I sent to Mr C as a suggested solution.

Notched log cabin log above the door to allow for contraction

Notched log cabin log above the door to allow for contraction

I recommended that this was done with his log cabin as this will allow it to contract unhindered.

The gap above the door and windows is necessary and can be adjusted if necessary.

If you are experiencing a gap appearing in your log cabin I hope this has helped and you know what to look for, if not please let me know and I will try to help.

Here are some more articles where we look at expansion and contraction in Log Cabins

Within all of this please consider your electrical installation in your log cabin, the building moves and your electrics should account for this: Electricity in Log Cabins

Log Cabin Contraction

At certain times of the year I will get the odd complaint about our Log Cabins from buildings that have been installed in the Autumn and Winter, Early Spring. The height of the complaints will come in around July and August.

Some customers will be nice and ask for advise, others will launch into a big complaint and are not very pleasant to deal with on occasions.

I then have to gently walk through the problem with them until it can be resolved and 100% of the time it is the customer’s own making.

The pleasant guy asking for advice will locate the problem and it’s solved.

The unpleasant guy will demand we go on site and then find the problem for them and all of the time it’s when they paid a ‘Qualified Carpenter’ or a ‘Qualified Joiner’ to install the building as it cannot be their fault.  Unpleasant guy then gets very upset when we charge for our attendance.

To solve this I thought I would write a quick post about this seasonal complaint and here’s a few examples:

Logs have shrunk in the heat.

Logs are coming apart.

Gaps appearing

Gaps appearing in the log cabin walls

Gaps and twists starting in the wall logs

Gaps and twists starting in the wall logs, this one is showing at the top of the wall

Gaps starting to show in a wall of a log cabin

Gaps starting to show in a wall of a log cabin, these gaps are spaced all the way up the wall.

Log Cabin shrinking

Log Cabin shrinking with gaps to the side of the door.

Gaps starting to appear

Gaps starting to appear

Contraction of Log Cabins

This quick piece is talking about the problems we have with contraction. No doubt, about six months from now, I will write one with the opposite problems, that of expansion, both are a powerful force in timber.

Throughout the articles in this blog I talk about expansion and contraction a lot and it cannot be overstressed the importance and the power of this. If you are going to own a log cabin you’ve got to believe me.

Here are some previous articles where I talk about this feature of timber in depth:

My online Log Cabin Advice Manual also talks about this.

Log Cabin Logs

A log cabin log is obviously made from the length of a tree and we try to pick the best bit close to the heart. It not going to grow or shrink much in its length but it can change quite a bit in its height when part of an install.

I’ve had a customer tell me ‘I realise wood moves but this is excessive’ It is not excessive, it is what wood does and it cannot be controlled or helped.

In the moisture content article above I reference some figures that will show a cabin has a potential to move a LOT!

Here’s a good example of a log cabin in contraction, followed by an expansion example. In either case you will see the untreated wood start to show. This is why I advise in other posts to remove the fascia and paint behind them so you do not see this happen either in contraction or expansion:

Contraction example:

Contraction exampe

Contraction example

Another contraction example

Another contraction example with untreated wood showing

Here’s the opposite, an expansion example, notice the original paint lines

Expansion example, notice the original paint line

Expansion example, notice the original paint line

Another example of contraction, please make sure you paint behind door and window fascia to avoid this.

Another example of contraction, please make sure you paint behind door and window fascia to avoid this.

Installation Problem

Of course none of this is helped if the installer is not aware of this or understands this and please believe me, anyone with ‘Qualified’ followed by ‘carpenter’, ‘joiner’ or ‘builder’ will make the same mistake as someone who has never built one before. The difference being of course your average customer will read the information before installing.

So why are we seeing these gaps and why am I having a complaint against our lovely log cabins?

Quite simply, the installer is trying to interfere with the movement of the logs and is restricting them moving. This will be things like:

  • Adding extra timber into gaps meant for expansion
  • Fixing door and window fascia to the logs
  • Fixing door and window frames to the logs
  • Installing shelves, electrics, brackets, 
  • Lifting door and windows up to fill expansion gaps
  • Fixing the logs in many other ways
  • Fascia in corner buildings above the door allowing the cabin to sit on the door frame

Here are some examples of the cause of all the above with pictures:

Fixed Fascias

This door fascia has been screwed to the logs. There was quite a few of these in the install

This door fascia has been screwed to the logs. There was quite a few of these in the install

Gaps appearing

Gaps appearing in a corner building. This is where the fascia above the door has been fixed and no allowance made for contraction allowing the door frame to slide behind it.

Fascia being fixed to the logs restricting their movement

Fascia being fixed to the logs restricting their movement

Door fixed to the wall logs

Door fixed to the wall logs – luckily I caught this one as the picture was for a door query but you can see nails through to the logs and this is a potential complaint in either expansion or contraction. Thankfully the customer removed these before any problems was caused in about 6 months time.

Timber infills

During the winter the wood is likely to be at its biggest and sometimes customers will worry about a large gap they find above a door frame or a window frame. Without realising what it is for ‘Qualified’ …. carpenters, joiners, builders … will be tempted to fill the gaps;

Timber used to fill the expansion gaps.

Timber used to fill the expansion gaps. In this example you can see there is a timber block above and to the side of the window frame. So with this Winter lead solution we come to summer and gaps are appearing all over the cabin and I get the complaint!

Extra timber placed above the door frame

Extra timber placed above the door frame. This wood block has removed all expansion and the whole log cabin will now be sitting directly on to the door frame.

Timber insert placed in the expansion gap

Timber insert placed in the expansion gap and also as an extra problem the fascia is also nailed into the logs.

DIY storm Kits, Brackets, Shelves, Curtains etc

I Haven’t really got pictures of these sort of things that I can show you as it may identify the customer’s cabin but this was an unusual one:

Strapping to act as a storm kit and bracing

Strapping and bracing. The customer had some sort of shelving system attached the sides of the cabin and I remember he was also concerned about bracing for storms as he was very exposed in the highlands. The ingenuity was very good but this was holding the cabin very rigid and when the summer got here gaps started appearing.

If you want to install shelves, black boards, bars, brackets etc you can do so really easily but please consider the expansion and contraction. The articles referenced earlier explains how to do this so you do not have any problems in the long run.

Electricity in Log Cabins

I wrote an article about Electrical installation in Log cabins ages ago and although I have let my personal accreditation lapse it still hold true and we reference this quite liberally, electricians must be made aware of the expansion in log cabins.

Here’s how to do it:

Flexible expansion to allow for the cabin to move.

Flexible expansion to allow for the cabin to move.

This is what can happen if you do not tell your electrician that a log cabin is made of wood and expands and contracts:

Log cabin has contracted and no allowance has been made for the trunking. This is a potentially dangerous situation as all the wire and terminations will be under strain.

Log cabin has contracted and no allowance has been made for the trunking. This is a potentially dangerous situation as all the wire and terminations will be under strain.

Consumer unit is fixed across two logs, this will cause problems in both contraction and expansion and may cause numerous problems least of all it compromising the installation itself.

Consumer unit is fixed across two logs, this will cause problems in both contraction and expansion and may cause numerous problems least of all compromising the electrical installation itself.

Summary of contraction in a Log Cabin

Log cabins move, whether it’s one of ours, someone else’s, regardless of thickness, all wood moves, it can’t be helped. It’s full of straws and these straws will suck in and expel moisture:

Layer upon layer of straws all drawing water for the tree. Many now support the Cohesion method theory where a tree draws its water using the tension of water.

Layer upon layer of straws all drawing water for the tree. These straws stay open and need to be treated to block them up.

You can see from the structure of the wood that these straws need to be blocked up, amongst other things this is the purpose of a good quality treatment and sufficient coats, these articles explain more:

I’ve said it several times, please don’t use anything cheap on any log cabin, we’re trying to inhibit the movement. A cheap treatment will not do this and you will have quite a bit of movement over the first year.

We do find though that after a year and the full season cycle we will never hear from a log cabin customer again. If you are going to have a problem with expansion or contraction it will be within the first six months of ownership as you will have either treated it well or the straws will start to collapse and die more.

If you have a log cabin that is showing these signs, before you complain to us or the person you bought it from whether it is our product or not please check the following:

Check for:

  • Fascia screwed / nailed to the logs
  • Any restriction to the logs at all
  • Shelves, curtains, brackets, fixings on the wall
  • Expansion Gaps above and to the side.
  • Finishes above Corner building doors.

This is all applicable to any log cabin, I hope it helps if you are seeing these problems whether you bought from us or another manufacturers building.