One thing to note with my build is that I was placing the new log cabin in place of an old shed, which was sat on paving slabs. Today, I broke a hole in the old shed floor to inspect the state of its base. While I wont be laying my cabin on the existing slabs, I needed to see how the ground was. Thankfully it was completely bone dry (surprising considering we've had the wettest few weeks in years!). With this in mind, I can now dismantle the old shed, leaving the ground covered with a tarpaulin sheet until the rain stops and I can lay the new base.
I'll explain in detail what I'm planning to do later in this post, but first, lets talk about the different types of base that can be used for a log cabin or garden office.
Choosing A Base
The first base type is the most obvious:
A concrete base is probably the most stable way to set up any shed. If you choose to go for a concrete base, you first need to dig out the land and level it, then place wooden shutter boards around the edge, do measurements throughout to make sure you've got the right size.
Once your shuttering is in place, lay a damp proof membrane. This will stop anything coming up through the concrete and help to keep it dry.
You can now lay your concrete. Depending on how heavy your building is will depend on how thick it should be. Realistically most garden office / log cabin structures are fine with 4 inches (10 cm). You can use ready-mixed bags from the likes of Wickes and Homebase if you wish, these work fine. Its usually best to see if you can get a deal on a wet concrete delivery as in some cases it can be cheaper. I personally wasn't able to find a good deal on this for my build when I first started researching.
There are a few important points to note with a concrete base:
- Try not to make your base any bigger than your shed. This encourages water to collect.
- Ideally, you should try and have the base above ground, so it's effectively 4 inches of raised concrete. This does wonders to stop water.
- The concrete can take up to a month to fully set, however in most cases should be fine to build on after 48 hours.
- Concrete actually loves water, so dont be too worried if it rains after you've laid it, it'll only make your base stronger.
- If you are extending an existing concrete base, drill into the sides of the old base and add metal supports, this will help bond the two bases together and prevent them separating.
I cant stress how much of a bad idea this is if you want your log cabin to last. A wooden base has very little support and will basically be completely rotten within a few years. I'm not going to go into detail on how to erect a wooden base, however I can only say this: dont do it.
Rased Concrete Base
Think about how a pier works, this method works in a similar fashion. You basically create concrete elevated molds (you can buy them ready made) and then place your wooden base on top of these, raising the log cabin up significantly.
The idea is that you add these concrete blocks under the base, and it created a strong foundation, way off of the ground.
A very similar method is offered by a few select garden companies that uses metal pads and poles to raise the base.
Now, this is the method I chose to go with. But before I go into detail, you need to know that there are more than one type of plastic base. There is 'Ecobase' style bases which aren't very thick (between 3 and 6 cm) and a more stable variation called 'HawkLok' or sometimes 'Forest Plastic Base', this is a much thicker, sturdier method where instead of ramming pea shingles into each hold (presumably to hold everything together), the plastic 'pads' each lock into each other, creating a sold, strong pad which acts much like a solid concrete pad.
When I first looked into this, I immediately dismissed a plastic base as being a bad idea, but the HawkLok style bas is actually pretty clever. It's been tested to apparently support over 28 tons per pad, and can be moved around and reused. For me, it worked out cheaper than a concrete base, and allows me to put it together myself in a matter of hours.
You start by digging out your plot (which is actually optional if you want the shed rased even more). You then place a layer of sand (again, optional but recommended) followed by a damp-proof membrane. You then lay your plastic bads on the membrane and lock them into place, once done you can move it around to get the correct position.
At this point, the base is complete...much quicker and simpler. I'll be doing a full review (and walkthrough) of the base once I get started (assuming the rain actually stops at some point!!)
I had many discussions with members of DIY forums and like myself, many thought the plastic bases were a silly idea and were only intended for small, light sheds, but they work just as well as a concrete base, and theoretically should be even better as they allow for a bit more air circulation, shouldn't get anywhere near as cold as concrete does, and can be reused. Only time will tell just how good they are though!