I used the jack just to get going it was the only accessible corner really. Supported with a lump of wood under both log ends. I didn't risk jacking only under one log end. The rest I used those bags all the way round. Would highly recommend them. They did a great job. from memory 4.5 x 2.5 ish.
I've just looked at your thread, Knobby - what a cracking solution (no pun...) I was going to suggest Snappy tries something similar, but never knew these small bags existed. I was going to simply suggest proping up all around the perimeter in tiny stages - a half-inch at most at a time - and slipping in spacers. This would be after removing the glass window sections... Keep on working around and around until you get it to the height you require. Hopefully you'd be able to get the edges raised to a point that the centre of the floor also raises, tho' it's bound to sag a bit. But if you need to lift it all, say, 2", then you'd likely need to get the perimeter up a good 3" before the centre rises enough. A wrecking bar (hopefully not living up to its name) would probably do this, with the fulcrum positioned close enough. That would make it a very (well, relatively) quick job. I don't see a different solution that I'd be happy to live with - the thought of all that damp, mould and possible rot taking place under the bearers .
I took up the floor and raised the bearers under the floor. With the sides in the air the middle sections were in the air just needed a bit more support with tiles under them. I'm much happier now I'm getting some air under it rather than it festering.
Was actually planning to lift mine but bearers are screwed to concrete. which is probably the best part of the build so far Looks like it's just gonna have to come down and re-build on a raised base of some sort.
Forget sitting it on bricks/timber and a DPC, sit it on recycled plastic beams, not cheapest but will not rot or soak up water. Acts as support and DPC. https://www.filcris.co.uk/category/boards-posts-and-sheets/posts/square-posts Any concrete base should be slightly smaller than footprint of building.
From thier website... "Please be aware that recycled plastic profiles will expand and contract with changes in temperature. This needs to be considered when fixing within a frame or between channels. Recycled plastic boards are more flexible than timber and will require more frequent supports than an equivalently sized timber profile"
I have a very similar cabin which I completed just before the heavy rain started. I could not paint it in time and it looks like the first one in the picture. I have exactly the same wet corner problem even though mine is raised above ground level on a frame. Plenty of air can get in and out underneath. I find that the wind drives water right through the joints. Mine is made from 58mm wide T&G boards. The wind drives water right through. It also drives water through any knots in the timber. Thanks to gravity, the problem is worse at the bottom than at the top. I ventilate the cabin every day and the inside moisture has cleared up pretty well. This moisture was from assembling it in the rain and everything got wet. It is now mostly dry but all corners and floor skirtings are wet. I am hoping that paint will reduce the problem.
For many years, I have treated (and or painted) timber before assembly. Then once assembled just give it a light sand and final coat to remove any marks through assembly. With anything like tongue and groves or "logs" it is more even more important as they continue to move exposing unpainted joints.
This has been very helpful guys thanks. I'm just waiting for a sell of dry weather to get mine started. I think after reading all your posts I'm going to lay a sheet of Dpm on the concrete slab then lay 4x2 bearers of my own on top of that then wrap the Dpm over the outer bearers, then put the cabin kits bearers on top of that
For what it's worth, I have a similar log cabin that I had at one house for 2-3 years, then moved it to a new house 5 years ago. I use a dirt base, polythene ground cover, then slabs on piles of sand (carefully levelled all 24) then the treated bearers sit on these. I've never noticed any damp or leaking in through the walls. The only moisture that gets it seems to come through a knot in one of the t&G roof boards, it must be near a nail hole from attaching the felt! This is such a small amount that it dries out before there is an sort of issue. Here's a couple of videos of the dismantle and rebuild process and you can see the base that went down for it.
Hi, slight resurrection of this thread. I have a similar problem but i feel the wind and rain is seeping through the wall nails which them soak internal wall and base. I have since trimmed back the dpm i fitted under shed in summer with toe-jacks. desperately want to insulate the shed for a man cave but need to watertight first any help most grateful