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Plastic Grid Bases

Perfect Cabins does not recommend using an interlocking plastic grid base for a log cabin.
These grids are OK to use for the playhouse for little Amy, or for your small potting shed, but are totally unsuitable to be used as a base for a heavy log cabin structure, where levels are crucially important to the longevity of the building.
There are several brands of interlocking plastic grid bases available, which are aimed at the DIY market, for customers that prefer something they can fit themselves, without the need to employ a tradesman. They claim to be very simple and quick to install, which is most appealing to people with little time or experience in base laying.
As they are lightweight and easily transportable, they appeal to those with poor access to the garden.
These grids are however quite expensive, and there are cheaper and easier solutions available.
We have had reports from customers that used these grids, saying they were a nightmare to level, which - as professional landscapers by trade - does not surprise us in the least!
The adverts give the impression that you can simply lay the grids down onto your grass, on top of a weed control membrane, then fill with gravel and hey presto! you have your log cabin base.
It sounds so easy in comparison to a concrete or paving slab base, and we can see the reason that some people are falling for these adverts.
They boast that, quote "You do not need any special tools or expertise". We would strongly dispute that!

If your ground is reasonably flat and solid, and the building is a lightweight shed, then it may be a quick solution for you.
A base for a log cabin MUST be 100% level in all directions. The difficulty in getting this right depends on the materials used, and the experience of the installer.
When you look closer at the specifications of most of the interlocking grid manufacturers, they explain that you will require a completely level sub-base. This involves digging out, removing soil, hiring skips etc. and leveling the ground, which is actually quite a specialised job.
It also means bringing in the sub-base material, usually crushed aggregates like Type 1 MOT (scalpings). These will need to be leveled properly, and then compacted with a wacker plate or heavy garden roller. If you don't have these tools you will need to hire them, which equals more expense.
The work so far is therefore basically the same as if you were having a full concrete base, which is actually much easier to level than these grids, and is cheaper!
If you have good access, then a concrete base is a good choice. If your access is poor there are various bases which are suitable: concrete blockwork, engineering bricks, concrete lintels, or see our Eco Timber Base.
Reviews from grid users
When a customer was placing an order recently, they mentioned they had used the grid base, so we asked them for their opinion. They said that the main problem had been getting it level, and that they wished they had not chosen to use it. They first laid a sub-base, and then laid the interlocking grids expecting the job to be reasonably easy. However, when they checked the levels with a spirit level, the base was nowhere near level. They decided that they should remove the grid, and they then added a layer of pea shingle and leveled it the best they could using a rake. After putting the grid back down on top of the shingle they found that it was still not level, and was falling slightly in two directions. As they could not afford to get someone professional in due to the high cost of the plastic grids, they again lifted the grid base, and this time added sharp sand and tried to screed it level. When they laid the grid again, the base was still not perfect, but they could not face removing it once more, so they were going to have to build the log cabin on top anyway! They said they planned to use some plastic shims under the bearers in the low areas. The whole saga had taken quite a few months, as they could only work at weekends. They told us that it had been a terrible experience, and they wished they had just paid someone to come in and lay the base for them in the first place!
Online reviews of various interlocking grid systems:
(Imagine, if it is this difficult for a tiny shed, how will it be for a cabin 6 times the size!)
"Don't bother! Get Concrete Slabs instead!

I bought this base for my new shed (the Keter Apex Resin 6x6) and, in all honesty, it’s a real pain to put together.

First of all, the dimensions of the base aren’t even 6ftx6ft, so when I assembled the shed there was a lot of overhang on every side, meaning we had to put stone chippings under each side to prop it up.

The sheet membrane that comes with the base is truly enormous. I didn’t measure it exactly, but it was easily about 12ft long. This meant we had to fold the membrane over, which meant putting the pegs in the ground interesting (more on that coming up).

The ground, obviously, needs to be completely level when you’re putting this base together. I don’t mean “there or thereabouts”, I mean COMPLETELY level in every single direction. I’d prepped the ground weeks before purchase, and even got the spirit level out to make sure it was all level. But when we put the panels down on top of the membrane, suddenly nothing was level. It turned out to be a combination of the membrane having ridges in it, the honeycomb centre of the panels cutting in to the ground at funny angles, we honestly spent about 2hrs trying to get the whole thing level but just gave up in the end and carried on regardless.

To hold the panels together, you get a lot of strange “U-shaped” plastic clips. The way we had the panels set up, we needed to use 14 of the clips to hold the panels together. You’d think that, given the “U shape” of the clips you’d put the two prongs in the ground to secure the panels. But no, you actually need to put the other, FLAT end of the clips in the ground! Meaning that, once the membrane is down and the panels are arranged, you then need to get on your hands and knees and violently stab multiple large holes through the membrane into the ground. Crazy.

In all honesty, I wish I hadn’t bothered with this base and had just bought some paving slabs and a load of sand. Would have taken me half the time to put that together compared to these plastic panels, and the Mrs wouldn’t have threatened to kill me 15 times when putting it together."
"You are swapping the self leveling nature of a typical concrete base for ease of installation. In other words you will need to put a lot more effort into leveling the site before laying your base. Few bags of MOT should do it, depending on exactly where it is going. Having a compacted level surface to put this sort of base on is the key issue so don't skimp on it."
"It did literally take minutes to click together and feels nice and stable. Took two days to properly level the site though. "
"A useful piece of kit, easy to use, only problem we had was leveling the ground"
Please Note: Perfect Cabins will not guarantee any cabin built on this type of base.
 Entertaining videos of a plastic grid construction
Video 1
Video 2

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Jun 27, 2017

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