Base for log cabin
Discussion
Hello all - first time poster (and semi-competent DIY-er), please be gentle...
I'm replacing a 6 x 4 garden shed with a 13 x 8 log cabin. The shed site on a concrete slab which isn't big enough for the log cabin, which will be built on a timber perimeter base.
This will go in the back of my garden, which slopes upward to the back fence. The concrete slab has been built above ground level, meaning that where it stops, the drop to ground level is 8 inches. I've attached a diagram showing the site.
So the options are as follows:
1. Remove and relay concrete slab to the correct size. This is not the preferred plan, for a whole bunch of reasons (including that everything coming out/in has to go through the terraced house, which makes big work pretty unpopular with the family);
2. Extend size of slab by pouring new border - but change in elevation, and slightly ropey nature of existing slab may make this difficult - I also don't particularly want huge amounts of new concrete in the garden for environmental reasons;
3. New foundation footings laid to match footprint of cabin, with cement blocks used to level (or perhaps cement blocks + plastic pads (yellow on attached plan) on top to hold the wood and slab to fully level and provide joist support).
Questions:
Does option 3 make sense?
If so, what kind of footings do I need to lay for the blocks? How deep/what materials?
How do I insulate the floor of the cabin? How would I support Kingspan (or whatever) in the section which effectively floats?
All help very gratefully received!
I'm replacing a 6 x 4 garden shed with a 13 x 8 log cabin. The shed site on a concrete slab which isn't big enough for the log cabin, which will be built on a timber perimeter base.
This will go in the back of my garden, which slopes upward to the back fence. The concrete slab has been built above ground level, meaning that where it stops, the drop to ground level is 8 inches. I've attached a diagram showing the site.
So the options are as follows:
1. Remove and relay concrete slab to the correct size. This is not the preferred plan, for a whole bunch of reasons (including that everything coming out/in has to go through the terraced house, which makes big work pretty unpopular with the family);
2. Extend size of slab by pouring new border - but change in elevation, and slightly ropey nature of existing slab may make this difficult - I also don't particularly want huge amounts of new concrete in the garden for environmental reasons;
3. New foundation footings laid to match footprint of cabin, with cement blocks used to level (or perhaps cement blocks + plastic pads (yellow on attached plan) on top to hold the wood and slab to fully level and provide joist support).
Questions:
Does option 3 make sense?
If so, what kind of footings do I need to lay for the blocks? How deep/what materials?
How do I insulate the floor of the cabin? How would I support Kingspan (or whatever) in the section which effectively floats?
All help very gratefully received!
trickywoo said:
Looks interesting, and seems like there's a few different suppliers... although no prices online - any rough idea how much these cost (appreciate there's specialist equipment needed to install and will vary by location etc) ?
Rhodeski said:
Looks interesting, and seems like there's a few different suppliers... although no prices online - any rough idea how much these cost (appreciate there's specialist equipment needed to install and will vary by location etc) ?
It’s a franchise I believe.I paid £40 a screw installed just over a year ago. I went for 20 but 16 would have done my 14ft x 12ft shed ok.
The guy put those 20 in by himself in half a day. My ground was pretty mich ideal for it. In the south east.
@uluru - that looks great, nice build. What did you put (if anything) underneath the paving slabs?
What slope do the paving slabs and timber supports deal with - my drop is 8" from front to back, and I'm not sure your solution looks like it would sufficiently fill the height.
Do you think stacking paving slabs would be ok to get to an appropriate height?
What slope do the paving slabs and timber supports deal with - my drop is 8" from front to back, and I'm not sure your solution looks like it would sufficiently fill the height.
Do you think stacking paving slabs would be ok to get to an appropriate height?
I had a similar issue where I had a large shed base but it was also sloped away badly. I was initially going to add more concrete around it and incorporate it to make one large concrete slab. I went with breaking up the old slab and having a new one poured. I want this to last many many years and didn’t want hassle of ground movement or pads/feet sinking etc.
The concrete slab cost me £750 which was pumped into the back garden. All I had to do was level the ground and knock up the shuttering. I had a guy with a mini digger level the ground as we lowered the bottom half of the garden. All in I’m was probably at £1200 for ground works and slab. The main conciliation being I know it’s not moving... ever.
Mine was a DPM laid under the concrete, and then some DPC under the bearers so the timbers shouldn’t get wet. I’ve also pour gravel around the back and sides to stop rain splashing up as advised and that works a treat too.
The concrete slab cost me £750 which was pumped into the back garden. All I had to do was level the ground and knock up the shuttering. I had a guy with a mini digger level the ground as we lowered the bottom half of the garden. All in I’m was probably at £1200 for ground works and slab. The main conciliation being I know it’s not moving... ever.
Mine was a DPM laid under the concrete, and then some DPC under the bearers so the timbers shouldn’t get wet. I’ve also pour gravel around the back and sides to stop rain splashing up as advised and that works a treat too.
FrankWebby said:
@uluru - that looks great, nice build. What did you put (if anything) underneath the paving slabs?
What slope do the paving slabs and timber supports deal with
Paving slabs were laid on mot type 1 on top of sharp sand. The supports themselves allow a range of 140mm (if you combine 2 different sizes) So probably not quite the difference you need. What slope do the paving slabs and timber supports deal with
Tuin supplied our log cabin this summer and the foundations were (in the true style of my other half) over engineered massively.
There's loads of advice on the Tuin website which really helps, but ultimately for a log cabin the base needs to be completely level.
Ours is (ignoring the over-engineered unnecessary amount of hardcore and sand) essentially a ring of well laid construction slabs. It seems to work well and the cabin hasn't shifted at all in the 8 months it's been up.
We just constructed the cabin, then built the floor as a floating floor inside on top of a damp proof membrane and filled the gaps with celotex.
There's loads of advice on the Tuin website which really helps, but ultimately for a log cabin the base needs to be completely level.
Ours is (ignoring the over-engineered unnecessary amount of hardcore and sand) essentially a ring of well laid construction slabs. It seems to work well and the cabin hasn't shifted at all in the 8 months it's been up.
We just constructed the cabin, then built the floor as a floating floor inside on top of a damp proof membrane and filled the gaps with celotex.
@uluru
I've noticed that you trimmed the overlap of the roof (it looks like it basically just fits a tiny bit wider than the footprint of the corner locking section). Any thoughts on that?
I'm going to have to do the same to, likely take 15cms off each side so that it fits my width (I'll have no side or rear access once it's up, so will be treating extensively as I build - but also it will be sheltered from weather by fencing).
I've noticed that you trimmed the overlap of the roof (it looks like it basically just fits a tiny bit wider than the footprint of the corner locking section). Any thoughts on that?
I'm going to have to do the same to, likely take 15cms off each side so that it fits my width (I'll have no side or rear access once it's up, so will be treating extensively as I build - but also it will be sheltered from weather by fencing).
FrankWebby said:
@uluru
I've noticed that you trimmed the overlap of the roof (it looks like it basically just fits a tiny bit wider than the footprint of the corner locking section). Any thoughts on that?
Not sure what you're referring too? The roof is flush with the top corner sections which is how they're designed, with the fascia board fitting in front. Are you mistaking the edge of the celotex we put on the roof as a cut edge?I've noticed that you trimmed the overlap of the roof (it looks like it basically just fits a tiny bit wider than the footprint of the corner locking section). Any thoughts on that?
No, but useful to see that - did you use any kind of additional moisture barrier/breathable membrane before finishing the roof?
My question was re the sides of the building - the overlap there looks to me like you've reduced it a little - I have a very restricted site, so will need to trim back pretty much to the overlapping corner width, so was wondering if you had any views.
My question was re the sides of the building - the overlap there looks to me like you've reduced it a little - I have a very restricted site, so will need to trim back pretty much to the overlapping corner width, so was wondering if you had any views.
Hi
I'm going to be in a similar situation. I'm going for the Aiste Log Cabin from tuin a 5m by 3m and ive spoken to a builder who will be making a Concrete base for me at 100mm in height with a sleeper edge which will be 100mm thick (ie sleepeers on their side running the perimeter of the base).
I will ring up Tuin beforehand to see if this is suffice but as far as I'm aware the base needs to be level as a must. I'm very wary too of over complicating the base.
Watching developments with interest here.
I'm going to be in a similar situation. I'm going for the Aiste Log Cabin from tuin a 5m by 3m and ive spoken to a builder who will be making a Concrete base for me at 100mm in height with a sleeper edge which will be 100mm thick (ie sleepeers on their side running the perimeter of the base).
I will ring up Tuin beforehand to see if this is suffice but as far as I'm aware the base needs to be level as a must. I'm very wary too of over complicating the base.
Watching developments with interest here.
Kingdom35 said:
Hi
I'm going to be in a similar situation. I'm going for the Aiste Log Cabin from tuin a 5m by 3m and ive spoken to a builder who will be making a Concrete base for me at 100mm in height with a sleeper edge which will be 100mm thick (ie sleepeers on their side running the perimeter of the base).
I will ring up Tuin beforehand to see if this is suffice but as far as I'm aware the base needs to be level as a must. I'm very wary too of over complicating the base.
Watching developments with interest here.
I've discussed with them, and also spent a lot of time on their (excellent) site - I've come to the conclusion that I'm going to use compressed paving slabs on top of a base of MOT, then sand/cement mix. Spacing these out every metre (or whatever makes most sense to provide support for perimetre and joists) leaves good air circulation under the cabin.I'm going to be in a similar situation. I'm going for the Aiste Log Cabin from tuin a 5m by 3m and ive spoken to a builder who will be making a Concrete base for me at 100mm in height with a sleeper edge which will be 100mm thick (ie sleepeers on their side running the perimeter of the base).
I will ring up Tuin beforehand to see if this is suffice but as far as I'm aware the base needs to be level as a must. I'm very wary too of over complicating the base.
Watching developments with interest here.
So my plan overall for the base/floor:
- DPM on top of existing slab
- Trench (depth?) around slab to footprint of cabin, filled with MOT, and topped with concrete pavers on base of sand/cement (maybe postcrete would do the job) to height 50mm above slab (slab level raised to level with pavers, using tanalised timber/additional thinner pavers)
- damp course on pavers
- Foundation beams built
- joists run at suitable intervals (say every 350mm), on joist hangers, with 20mm expansion gap at each end
- 50m Celotex or similar (does anyone recommend a particular product?) inserted between joists, with support from below as necessary
- - - WALLS BUILT - - -
- some kind of membrane/vapour barrier - (anyone know what I should be using)?
- 18mm? OSB sheet pinned to joists
- Underlay
- Carpet/laminated floor
Edited by FrankWebby on Tuesday 15th January 11:59
Balmoral said:
I'm not so sure about compacted MOT and pavers, I had a base built like that for a large cabin 3 years ago and it's settled and shifted. Job for this year is to dismantle it, put a concrete base down and reassemble it. Wish I'd gone for a concrete slab raft in the first place.
I built mine to last.... forever ! Was going with screws and pads, then thought about concrete lintels on compacted MOT. Eventually I settled on going mad as I want this thing to last 30+ years after spending 7k on it. I had the ground levelled and then had a 4” thick reinforced concrete slab poured. Yes it cost about a grand with the wood for shuttering, reinforcing sheets and then having Concrete pumped into my back garden with me doing little to no work. I know now it will outlast anything I stand on it (within reason obviously)
They managed to back this beast down into my little corner
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