Timber Frame Base for Log Cabins

I’ve been pondering this post and am slightly reluctant to write it as I am NOT a structural engineer. I have lots of experience with timber but I am not at all qualified to give technical advice and specifications, so please read this post in the spirit it is meant.

You have no come back on me personally if anything goes wrong, the design of this is completely down to you but I will give some advice and ideas based on my experience.

Since I highlighted this type of base in my log cabin base requirements  page we get lots of questions on my very favourite base:

The timber frame base for log cabins.

What I love about a timber frame base is that:

  • It can be moved.
  • It’s truly a temporary structure which is great in certain circumstances.
  • It allows air flow and therefore the timber will never rot even if it’s not treated.
  • It’s very easy to create a level base in very unlevel areas.
  • It’s a cheap solution in inaccessible areas for concrete.
  • Cheap overall.
  • If subsidence occurs you can simply jack up the area concerned and re-pin.
  • A good system when flooding occurs naturally and does not affect it’s environment.

No doubt you’ve done some research on all the types of bases you can use. You’ll have perhaps come across various types of pads, plastic grills, jack type things, easy bases, there’s all sorts of gadgetry out there. If concrete or paving slabs is not a solution for you you can’t beat good ol’ wood over all the gadgets and alternatives there are.

Stick to Wood

My advice is to stick with wood and don’t waste your money on the gadgets, you know where you are with a good lump of wood:

  • It’s relatively cheap when compared to other ‘gadgets’
  • If treated and looked after it lasts forever (ish)
  • If anything needs replacing you can do so easily.
  • If you need more it’s readily available.

A timber frame used as a base for a log cabin does not need fancy timber, rough sawn from your local builder merchant is perfectly adequate but it would ideally be pressure treated (tanalised – More information on tanalised timber)

What size timber to use?

I’m often asked what size timber to use, as I mentioned, I’m not a qualified engineer, don’t necessarily go by my advice but I like big, chunky and manly bits of wood. Something like 150mm x 50mm and then laminated and used under every log forming 150mm x 100mm, sometimes for bigger buildings even bigger. I don’t have structural calculations, this is all touch and feel. I think anyone with any slight experience can look at a piece of timber and decide if it’s strong enough.

Here’s a base I was involved in:

This is the start of a timber frame base for a log cabin. Notice the size of the timber we are using, this has been laminated together to form the frame.

This is the start of a timber frame base for a log cabin. Notice the size of the timber we are using, this has been laminated together to form the frame.

This base went on to support one of our biggest standard log cabins: The Edelweiss 70mm log cabin You can see here how we have joined wood together to form the main frame. Sometimes you can do it in two sections, two rectangles and then join them together. Notice also the posts we are using, I like big and these are nice big lumps of timber. Alternatively though you can also laminate your timber to make these. I prefer to see the support posts directly under a join as you know it is always going to be supported if screws or bolts fail.

This was another one I was involved in, this example was not actually for a log cabin but the same principle applies:

Posts are longer so we introduced some lateral bracing

Posts are longer so we introduced some lateral bracing

Notice how the post supports are under the joins in the corner and middle. This one was made in two rectangles and joined together in the center. As your support legs get longer lateral bracing is a good thing to consider.

Supporting your timber frame base

I’ve tried a few things in the past and looked at a few more. I’ve had a go with the plastic grids you can get but I still don’t really see the point of them apart from they’re a bit lighter but I worry about the longevity of them. Great in a greenhouse but I still think you can’t beat a nice solid slab on a bed of sand, or sand and cement. Make sure though of the stability of the ground underneath as you don’t really want subsidence in years to come.

A suggestion on a good timber framed base

This is just a suggestion on how I would build a timber frame base for your log cabin, it’s not gospel, it may be wrong, remember I’m not a structural engineer or a qualified landscaper so you need to design your own way of doing it. My ideas might help though.

Timber frame base example of the way I might do it depending of course on the size of building

Timber frame base example of the way I might do it depending of course on the size of building

This is just an example and my personal thoughts (you may have your own) on how to make a good timber frame base for your log cabin. The main points in my personal design are:

  • I’m using a standard size timber, all of the same size, maybe 150mm x 50mm (6″ x 2″)
  • Laminated around the perimeter of the cabin walls for strength – Basically I am screwing / bolting with coach bolts the timber together every 1m or so. For bigger buildings I might use thicker timber. Every wall will have this support under it.
  • I’m using chunky support posts under the joints. Either use big 12cm timber posts like we supply or consider laminating.
  • You may want to consider, depending on the size of your building, using noggins to stop lateral movements of the joists
  • Incorporate your floor joists within the timber frame base. Our floor packs for log cabins are designed only for a flat and level base such as concrete or paving slabs. Joist in your house are normally spaced at about 300mm apart, it’s a good idea to use this measurement in your log cabin floor. If you are using the cabin for heavier items, treadmills, heavy machinery etc, you may want to consider them closer.
  • You will NOT need to use foundation beams under the first log. The sole purpose of them is to keep the first log away from ground contact, you are already accomplishing this with a timber frame base for your log cabin. With joists incorporated in the frame this will also give a better finish and everything will be at the same level.
  • The outside of the timber frame should be identical to the footprint listed with every log cabin to properly support the log, bear in mind the log thickness of your building though as it’s good to have a lip on the inside of at least 25mm for the floor to sit on.
  • If you feel like being clever bring the frame in by 2 – 5mm from the footprint and this will then set the frame in slightly giving a drip for the logs and you can be sure water will never sit against the first log
  • Consider using joist hangers for the floor joists as these will be easier and quicker.
  • If your post supports are above 300mm I would start to consider lateral supports to stop any movement.
  • Consider your spacing of posts support. I like to support every 1.50m depending on the building and thickness of timber.
  • Consider using Weed Control Matting under the base – nettles grow anywhere!

That’s pretty much it as far as I’m going to help you.

Hopefully you now have some ideas of your own. The principle is quite simple. Make a frame for your log cabin to sit on, make sure it does not subside, make sure the wall logs are supported. Above all make sure it is properly, 100% level! Oh and jump on your frame before installation – this is my technical test to check whether it will work 🙂

 Some examples of timber frame bases for Log Cabins

Here’s some examples of what others have done, all of them work. It’s up to you what information or ideas you take from this post ……

This is at the shallow end

This is at the shallow end of a build, notice the use of noggins to stabilise lateral movement of the floor joists.

The higher end

The higher end of the project. A timber frame helps you level out a very unlevel piece of ground and often cheaper. Notice the supports are smaller but a lot more of them. I have experimented in the past with simple stakes in the ground – lots of them but it worked well. This is what is happening here.

Perfect

Perfect! I love this base, massive telegraph poles as supports, good chunky timber and floor joists on hangers.

Smallr

Smaller timbers are used here, this customer has used a different support system and is screwed in from the side, it’s working and nothing wrong with it. It can also be adjusted easily.

same

This is the same customer as above, he created the frame, built the cabin and is now going to put in the joists. A good idea to do it afterwards as it does not hamper your build of the main log cabin.

Floor joists

Floor joists are now being added. I would have liked them closer together but of course it does depend on the thickness of your floor / decking boards you are going to use. There’s no right or wrong answer when it comes to a timber framed base.

floor

Floor going in on top of the floor joists.

post

Here you can see some chunky posts which I like, they’re also using large rough sawn timber with joist hangers for ease. After the build you would then clad this to make it look pretty. This is our Torsten Log cabin

osb

You can see here the floor joists used on joist hangers supporting an OSB floor used because they are going to put a final floor covering down so they do not need our posh Spruce timber floor.

detail

Noggins being used to stop the lateral movement of the floor joists. See also how thick the timber is in the frame

post

Again see the size of timber being used. Timber frames do get you out of a levelling problem and save quite a bit of money, it’s worth considering.

intersting

Not a timber frame but an interesting consideration, this customer is using up stand slabs and then using joist hangers to support the floor joist.

floor

A joist system has been created with a timber floor on top before the cabin is put on top – interesting and clever!

Joists

The base I was involved in being extended with noggins, joist hangers and supports and following a system we had put in place to extend further.

pretty

I love a timber framed base, so much can be accomplished. This does look good!

This post is not official advice, it’s nothing to do with Tuin or Tuindeco, all mine and I often get things wrong (so my wife says) take from it what you can but a timber frame base for your log cabin can get you out of a lot of problems and expense.

I hope you have some ideas? If you do please share them.

To make leveling the base we do have a nice product. It’s not a bad price either and you can level between 30mm and 140mm using a combination of two units click on the picture for more details:

Very useful pads for easily supporting and leveling a timber frame base for your log cabin

Very useful pads for easily supporting and leveling a timber frame base for your log cabin

More examples:

29 thoughts on “Timber Frame Base for Log Cabins

  1. We’re currently awaiting delivery of an Aiste cabin and are currently preparing the base. We’ve opted for a nice timber frame with joists, noggins and thick insulation in between. My question is relating to the damp proofing… I’ve read that it’s better to put a sheet of DPM across the whole of the floor once the base is built and insulated. Thus, the cabin will be placed immediately on top of the DPM. Is this correct?

    • If you are using a timber frame base I would be putting the DPM under the timber frame. You could put in on top but I think it better underneath if it is possible within your design.

      • Thanks for the prompt reply Richard. It should be easy enough to attach the DPM underneath, although the frame certainly weighs a fair amount now, so tipping that up and stapling will be interesting!

  2. Hi Richard,
    In a real spot of bother here and really wondering if you can help out. I ordered one of your Daily log cabins and have someone coming over to build this for me. I have a concrete slabbed based which I got ready during the summer. I thought it was flat but have been told by the builder it’s not 100% even and that the best thing to do is put decking on top of the slabbed base and then build the cabin log. My concern is I really don’t want to spend more money on getting decking in first and also that I don’t fully understand the benefit of this. Is there anything else I can do to build the cabin log on the slabbed base but with a timber base or something to compensate for the 5-6cm of unevenness. Any advice would be appreciated thanks

    • Ideally the base should be 100% level as the logs will then sit correctly and you will not have problems with subsidence and moving. You could try using timber packers to try to level it and then seal the gaps. 5 – 6cm out is quite a lot though. You will need to make sure the logs are supported throughout their length.

  3. Hi Richard, plenty of great advice here! I have an existing concrete base 3mx2.5m. I need a 4.1m x 4.3 m base for a Meaghan cabin. Should I: rip out the base and put down a timber frame one; add a timber frame to existing concrete base to save digging it up; or add more concrete to existing base. I am drawn to the middle option! All views gratefully received.

    Steve

    • I think if I was making this decision it would be based on the condition and quality of the existing concrete base. If it was good, level and square I would consider adding to it, I would also make sure i use timber to act as an expansion / contraction joint where the old concrete meets the new. If the base was not viable I would remove it completely and consider replacing it or indeed using a timber frame base.

        • I have seen them and used them in the past, they’re light and easy to handle which can be an advantage. They certainly seem strong enough but you will still have to prepare the ground as you would with a normal paving slab. normally you fill them with pea shingle. Also, they’re normally more expensive than slabs.

          The downside for a log cabin, for the way we like to see them constructed with a foundation beam around the perimeter, is that it is impossible to seal the base to the foundation beam. So, the only way to make them work is to use bearers like you would a shed which then defeats the object.

  4. If I’m buying a daisy cabin 3.5 x 2.5 what size timber frame should I construct?

    The internal measurements are different?

    Frame 3.5 x2.5 or
    Frame 3.3 x 2.?

    Help please

    • If you are using a timber frame base with a log cabin you will ideally make it to the footprint of the cabin. The footprint is the overall dimensions less the corner interlock. In most cases the interlock will be 100mm. With a Daisy Log Cabin the overall dimension is 3.50m x 2.50m. Therefore the footprint and minimum base size required to support the full length of wall log is 3.30m x 2.30m.

      On most log cabin pages the footprint size (minimum base size) is given for each building.

      • Hi Richard, I saw that, stupidly I’d done the framework to 3.5m x 2.5m before hand, it’s not secured/cemented yet but bolt holes done??

        Should I re do it to the 3.3 x2.3 specs or just go with the bigger frame?? Which tonne fair is fairly substantial

        Chris

        • If the walls are only supported at 3,5m x 2.5m then only the interlocks will be supported, this will not work at all as the main wall needs to be supported throughout its length.

          See this picture for an explanation, you will see the interlocks, they sit outside the footprint: ?w=818&ssl=1″ alt=”Log Cabin Diemsions” />

          If it is not possible to adjust the size to the footprint or it will take too long I would consider adding extra timber in to accomplish the footprint.

          • That makes total sense, thankyou Richard, I’ll look at it tommorow! Might just laminate the internal to fill the footprint!

            Great service, thanks again

            Chris

          • Please let me know how you get on. Pictures are great for other people with their bases and are much appreciated and help others greatly in the same position.

  5. Total novice here (sorry) I’m building wooden frame to hold a 3.5 x 2.5 (man cave/bar) so far I’m using 4×4 posts set with post Crete? Then I’ll use 4×2 framework laminated around the outer frame? With joists across using joist hangers? With posts every meter? And joists across?

    Does this sound ok?

      • Give all wood a good coating in creosote, you may never get to paint them again. I also put a layer of damp-proof member between the joists and cabin, this only has to be a thin layer of plastic sheet. Stop any damp reaching your cabin from the ground.

    • I cannot quite get my head round the advantage of laminating. I would have thought that a 6×2 would give more resistance to downward forces than two 4x2s laminated

        • Larger pieces of wood cost more money, bigger trees. By laminating you use up cheaper wood, combined to get the same strength. If you have a source of larger cheap timber, use it instead.

  6. Great help, thank you so much. My log cabin is 5.5m x 3.5m maximum sizes and has been ordered, so I need to get a base made ASAP.
    I am considering 12cm tanalised posts, concreted into the ground, which is sloping and clay soil. 5 posts wide by 5 posts deep to extend a give a 1m surface out-front to use as a path and small decking area.
    Am I right in presuming I do not need to put decking on the whole lot, the log cabin bearers will sit across the frame and the flooring will go on these. With weed control on the ground. Or do I need to fully deck the whole framework?

    • If you are using a timber frame base it is better to incorporate the floor joists within the base frame. The cabin can then sit directly onto the frame and also the floor boards. You will not necessarily need to use the foundation beams as you are already accomplishing their purpose which is to take the first log away from ground contact.

  7. I’m planning my first log cabin build (4m x 3.5m ) so some useful advice here for sure. I will build a doubled-up frame of 7×2 with joist hangers. I intend to make corner foundations using breeze blocks on top of large paving slabs (60cm x 60cm). However, what ground preparations should go beneath the paving slabs? I have seen mention of sand and cement elsewhere but surely this would eventually subside? I want to avoid the laying of concrete if possible. Perhaps some further breeze blocks/rubble beneath the slabs with a small amount of concrete to bind them together would prevent any movement?

    In between the corner supports I want to take a slightly different approach and use levelling machine feet instead of wood blocks. They are like the little adjustable feet on the bottom of a washing machine, but about 10 times bigger and can take 1.5 tonnes each. Because the ‘foot’ part is rubber, there should be no rising damp into the building and because they self-level, the blocks they sit on do not need to be perfectly flat. Have you any thoughts/experience with this method?

    • Sand and cement can work under the foundation but I prefer to be certain and would add some hardcore underneath to ensure stability. This does of course depend on your ground conditions, a sandy soil will obviously require more.

      I’ve used something similar to your leveling blocks, we in fact sell something similar and they work very well, an adjustable support can save a lot of time mucking about but personally I still prefer timber and leveling it from timber posts. I also think it looks better and easier to trim.

  8. My experience of buying timber is that some is always warped, sometimes very much so. When laminating a timber frame and trying to get it level, what are the solutions? Buying largely unwrapped timber or can it be massaged into a level way? Or is it the case the Cabin will straighten it out with it’s weight?

    I have purchased a Stian and a Ben Blockhouse and am considering timber bases for both.

    • This is not something I’ve really had a problem with, but when a piece is very warped then you can use noggins to maintain the level and straightness. For larger buildings we tend to create separate frames and then bolt them together. This maybe why we have not had problems with warps as the whole base is made of smaller framed sections. For your Stian I would do it as normal. For the Ben Clockhouse due to its size you could consider making three separate frames.

  9. I’m planning my first log cabin build, this content is really useful – thank you! I am favouring a timber frame base because the ground is pretty uneven. The soil is clay heavy so I am worried about waterlogging and future movement. What are your views on embedding the support posts in concrete forms rather than sitting on cemented slabs. The cabin will be 44mm thick, 3m x 3m with a 3m x 3m gazebo and an extended deck area: whole area is 36 square metres.

    Thanks,
    Dave

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