The most important thing about a log cabin base is that it needs to be level and able to take the weight placed on it over a prolonged period of time. Most log cabins, unlike a typical shed, will have the majority of their weight taken at their perimeter. Generally the base should have a footprint slightly larger than the cabin going on it.
There are four main designs of cabin bases: concrete, gravel foundations, paving slabs and timber frame supported by stilts.
The simplest way to do this is to use timber edges and fill the base to a depth of 8 10cm. For a large cabin you might want to have steel reinforcing. The critical issue with the timber perimeter is that it is level so that you can fill the excavation to the level of the top of the timbers.
This is not a job to do the day before the cabin arrives as the concrete may take several days to cure. The surface doesnt have to be level to the exact millimetre but the more you keep working the surface with a blank across the timber perimeters the better it will be assuming the edges were completely flat.
See our simple guide to making a base - concrete-base guide (PDF)
Better suited to small cabins, you can find a explanation of this technique here
A quick and cost-effective method of making a base just requires a sand/cement mix (1 part cement to 8 parts sand) or gravel base to a depth (depending on weight) of 510 cm and is relatively simple to get level. Recommend to use a plain concrete slab approx 4cm thickness
Timber frame supported by stilts
The timber frame that you use can simply be supported by paving slabs positioned at intervals which has the advantage that you can move it around. It is a good solution for areas where the ground is sloping or very uneven (because it is relatively easy to adjust the height of the stilts) or where access is poor making pouring concrete a difficult option.
The main criteria for a long lasting and stable base is therefore:
- It should be just over the footprint size of the cabin
- It should cope with the majority of weight being at the edges
- The depth of the based relative to the weight it will have to take
- Completely level in all directions
- Use of a good damp proof membrane (if it is not supported by stilts)
Finally, remember not to place the base too close to any walls or fences as the log cabin may have a slight overhang on the roof. Also, placing the base next to trees or large plants could also cause problems with root damage or branch overhang. Fast growing trees like sycamore, pines, leylandi etc could become a headache in 5 to 10 years time.