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 in Log Cabins

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

Inside a Log Cabin

I’m quite often asked what a log cabin looks like inside. I think maybe some customers think it looks like a shed with a frame, a bit ugly with bits protruding. A log cabin looks the same inside as it does outside.

This what a shed inside looks like:

The inside of a shed and perhaps not the most pleasant of places

The inside of a shed and perhaps not the most pleasant of places

It’s not the greatest looking thing, it will show the framing and has bits sticking out,  it can of  course be approved on with a lining but it still a shed.

A log cabin is a completely different proposition. It’s smooth, it’s planed with no rough edges. We make a big thing of choosing Spruce for all our log cabins and this makes quite a bit of difference in the look and feel of the building. It is a whitewood and maintains it’s light appearance. It doesn’t turn red like pine does with sun on it and the knots are a lot fewer.

So, lets see what a log cabin looks like inside, here’s a basic example:

This is the basic inside of a log cabin with a floor fitted

This is the basic inside of a log cabin with a floor fitted

Once your log cabin has been built this is what it will look like inside. Both the wall logs and floor is finished as planed smooth.

Here’s another picture, this is the shed side of a Lukas Log Cabin:

Lukas log cabin shed area, our customer has made great use of left over timber to product some shelves.

Lukas log cabin shed area, our customer has made great use of left over timber to produce some shelves.

Here’s a peak at the Edelweiss log cabin mezzanine floor area:

Edelweiss mezzanine floor

Edelweiss mezzanine floor

So that’s what a basic log cabin looks like, so lets see what customers have done with their buildings:

Viggo log cabin, our customer is adding his beds onto his own laminate flooring.

Viggo log cabin, our customer is adding his beds onto his own laminate flooring.

The Stromastand log cabin being used as a garden office

The Stromastand log cabin being used as a garden office

This is the Rome log cabin, a family enjoying the building with a hot tub

This is the Rome log cabin, a family enjoying the building with a hot tub and its use is as a therapy room.

Another view of the Rome log cabin being used as a therapy room

Another view of the Rome log cabin being used as a therapy room

Inside a Santrov log cabin, simple and practical.

Inside a Santrov log cabin, simple and practical.

A nice sofa arrangement in one of our log cabins

A nice sofa arrangement in one of our log cabins

Our Stromstad log cabin being used for a therapy studio and office

Our Stromstad log cabin being used for a therapy studio and office

One of our log cabins being used as a pilates class room

One of our log cabins being used as a pilates class room

The inside of one of our Ingrid log cabin designed for a corner location.

The inside of one of our Ingrid log cabin designed for a corner location.

This is a picture of my Friends Henning log cabin - He now virtually lives in it much to his wifes upset.

This is a picture of my Friends Henning log cabin – He now virtually lives in it much to his wifes upset.

A simple scene from a Gustav log cabin.

A simple scene from a Gustav log cabin.

Our Edelweiss log cabin, a large and very versatile building.

Our Edelweiss log cabin, a large and very versatile building.

As mentioned in our Uses Of A Log Cabin blog post, our Cabins are often used for craft/hobby rooms and workshops:

This slideshow requires JavaScript.

This slideshow requires JavaScript.

 

This slideshow requires JavaScript.

Our customers love to turn their Log Cabin into garden bars, for example, this Julia Log Cabin being used as a pub right in their garden!

This slideshow requires JavaScript.

And if you just want somewhere where you can relax and regain your thoughts… The Emma Log Cabin is the perfect size for a lounging area:

This slideshow requires JavaScript.

How about this customer, who turned his Justine Log Cabin into a cosy man cave:

This slideshow requires JavaScript.

Another Log Cabin used as a business front- This customer used the 5m x 4m Klass Log Cabin to give them plenty of space to promote their mosaic designs, as well as a sitting area for their customers:

This slideshow requires JavaScript.

This slideshow requires JavaScript.

This slideshow requires JavaScript.

Meaghan Log Cabin

The Meaghan 4.5m x 4.5m Log Cabin provides a suitable base for an office area.

This slideshow requires JavaScript.

This hideout spot is inside a Gijs Log Cabin fitted with a log burner in the corner to keep the cabin cosy in the winter months:

Inside The Gijs Log Cabin

Our Petit Log Cabin is often used as a shed, due to it’s size of 2m x 2m. That’s why our interest was pipped when these customers showed us how they turned their Petit into a cosy island paradise:

This slideshow requires JavaScript.

I think you can probably get the gist now, log cabins are nothing like a shed. It’s smooth, sleek and very bright, you can create whatever atmosphere you would like to, just make sure you buy a Spruce one though!

You may be also interested in other customers buildings posts and thoughts:

Double Glazing in Log Cabins

No doubt you will have seen across a lot of the suppliers of log cabins in the UK that EVERYONE offers double glazing, AND they offer it with everything, I’ve even seen a 19mm cabin with double glazing as an option – amazing!

You may have noticed we do NOT offer double glazing with everything. There’s a reason for this ….

Double glazing in log cabins - all of our 58mm and above are but why isn't it offered with thinner logs much?

Double glazing in log cabins – all of our 58mm and above are but why isn’t it offered with thinner logs much by Tuindeco?

When I’m asked for double glazing in 28mm log cabins I tell customers that “there is no point to it and the walls are not thick enough to warrant it or the extra expense for it”

This post helps to explain more about why I say this.

Before I get onto the double glazing first of all have a look at this:

Heat Loss from a Building

Typical heat loss in any building

Typical heat loss in any building

This is very self explanatory, 25% is lost through the roof, another 10% is through the floor so before we worry about the glass, lets get that 35% sorted. Have a look at my recommendations for insulating of a log cabin roof and floor. That will take care of 35% of our worries. Please keep in mind that 50mm of Celotex or similar has a R value of 2.25 and a U value of 0.44 – we’ll come back to this.

We can also quite easily get rid of another 15% caused by drafts. All our cabins are made extremely tightly, sometimes too tightly. The moisture content is 14 – 16% in our log cabins and we use proper corner connections, drafts are kept to a minimum. Sure sometimes a fitter will add extra trims, sometimes you might want to add a little more to the building. Drafts though can easily be stopped.

So, that’s taken care of 50% of the worry of heat loss; Insulate the roof and floor and keep the drafts down!

Log Cabin Walls

Now let’s look at another big chunk, a whopping 35% of the building  – the walls!

Wind and watertight connections on all 90 degree corners.

We offer a large array of log sizes depending on the use you would like to put your log cabin to.

You will have seen from the range that there is something for everyone, we offer lots of different styles with varying log thicknesses and this is borne from experience of the uses and requirements for each thickness. It stands to reason that a thinner log has less thermal efficiency than a thicker one, so lets look at our most popular sizes: 28mm , 45mm and 58mm.

R Values and U Values

This is where it gets a bit heavy but bare with it.

R Value: This is a measurement of the resistance of the flow of heat through a given thickness. This is mainly for a solid material such as a lump of wood, in this case Spruce. Once a R value is found it can be converted to a U value. Higher the R value the better!

U Value: This is a measurement of heat loss in watts when the outside temperature is at least one degree lower. It is often made up of the sum of parts such as double glazing (glass and air) Lower the U value the better!

Spruce Log Cabin Logs – R Values and U Values

I did a lot of research on this recently, some people are giving some crazy figures, one UK supplier I found was giving mad and very misleading figures. I have though tried to be quite impartial with this. The lowest figure for Spruce is the American R value of 1.41 / inch with a 0.1 / inch increase due to the thermal mass of the timber. I have then applied a European conversion from US R Value to the European R value (multiply by 0.1761)

By my very low and conservative calculations the three popular sizes of dried Spruce Log came out as:

  • 28mm Spruce Logs – R Value 0.29 – U Value 3.42
  • 45mm Spruce Logs – R Value 0.45 – U Value 2.21
  • 58mm Spruce Logs – R Value 0.61 – U Value 1.64

An 18mm Spruce roof board is – R Value 0.19 – U Value 5.16

As a point of reference:

  • 1976 the U value for a house wall was 1.7.
  • In 1985 it was reduced to 1.0.
  • 1990 reduced to 0.6
  • 2002 reduced to 0.35.

You can see from this that a log cabin in these wall thicknesses is never going to be as good as your house, not without extra lining at least. You can though also see how much more heat is lost through a 28mm thick log cabin and the roof loss is just huge on any log cabin if you’re leaving just the roof boards.

This is where you need to make a decision on what the log cabin is going to be used for? A leisure building, summer house, a shed / storage type of cabin is perfect as 28mm. For an office or accommodation 58mm or above is a must. 45mm is the middle ground and you will need to make some trade offs. Of course you could also go thicker, 70mm – 90mm ,120mm and so on but there is always trade offs between the product cost and heat savings.

Of course if heat retention is a big concern any of the buildings can be lined and then further insulated, in fact we have a trade partner who does just this, with design and good internal insulation they get the U values down to 0.5.

A Log Cabin solely on it’s own will never get to these levels, especially 28mm or 19mm not without a LOT of extra work. Maybe save the extra work and look to thicker logs?

Roof and Floor – 50% of heat loss

Remember the roof and floor insulation I recommended above gave you a U value of 0.44. If heat loss is a consideration at least fit this to your roof and floor, we know that 50% is lost through drafts, the roof and the floor. This area is the MAIN worry before moving on to double glazing your log cabin.

Double Glazing in Log Cabins

So, we’re down to the last 15% of heat loss, the windows and double glazing.

Here are the Values to consider, remember: Higher the R value is better and Lower the U value is better.

  • Single pane of glass – R Value 0.94 – U Value 1.10
  • Double pane of glass with an air gap – R Value 1.93 – U Value 0.52

Have a look at these figures and compare them with the log cabin figures I gave you earlier:

  • 28mm Spruce Logs – R Value 0.29 – U Value 3.42
  • 45mm Spruce Logs – R Value 0.45 – U Value 2.21
  • 58mm Spruce Logs – R Value 0.61 – U Value 1.64

An 18mm spruce roof board – R Value 0.19 – U Value 5.16 – This can easily be rectified though by adding roof and floor insulation in your log cabin.

It’s interesting to see isn’t it, this is why double glazing is not offered with everything, there really is no need for the customers extra expense.

A 28mm log cabin with a U value of 3.42 cannot benefit in any way from double glazing at 0.52 as more heat is going out of the walls than the glass widow, the same can be said for 45mm but it does start to make sense with the 58mm log cabins.