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Shed Base

A website dedicated to the construction of an accurate 1/2 scale replica of a 1927 Aero Douglas Motorcycle

Once you have permission to build a workshop (make sure you have the relevant planning permission, or in the case of new build homes, consent from the developer and finally from your partner) it is time to lay a base.  

I'm going to run through the method I used as it is easy to do, removable and inexpensive.  I have used slabs laid on a sand and cement mix layer, but other methods include: A fully poured concrete base which can be very time consuming and a wooden beam base where the shed rests on a series of thick wooden beams direct on the ground allowing air flow.  Google is your friend and there are many sites out there showing all the methods above.

The garden before all the fun began.   The first thing is to work out where the workshop is going to sit.  Access to the garden is vital in the final position as moving machinery through the house is a bad idea and I have to get my motorcycle inside too.

The position of the doors on the workshop 


Once you know where the shed base it going,  it is time to get the slabs you are going to use.  Any slab will do but I would stay away from the heavily textured slabs as they are harder to get level due to their uneven surface and you're not going to see them after all.  On that point, I got mine second hand and as long as they are the same size width wise, in my case 45cm, they will do fine.  

I was advised to have at least a 9" gap between the fence and where the shed would sit but I would suggest that is upped to 12" just for painting and maintenance.  Using the known footprint of of the shed plus the gap I was able to work out how many slabs I needed.  

These were laid out on the grass in their final position, rope guidelines were then set out to mark where the grass is to be lifted.  

The spade was put into play and the grass lifted up to the marker rope to a rough depth of 2".  You can see the clay soil underneath that will cause my garden to look like a ploughed field at the end of this process.  Items like bricks can be left in so long as they are compacted down below the surface before laying.  

I lifted the turf in sections of 12" x 8" to make it easy to carry as it's surprisingly heavy.  No one wanted my turf so I ended up taking it to the tip in many trips, what a waste!  Do not let lifted turf sit on your lawn for long periods of time as it will kill the lawn below it, especially during the rainy season.  Here in the UK, that's pretty much all the time. 

All the turf has been lifted and disposed of.  Now it's time to compact the soil where the cement and sand mix will be laid. 
In the 1700's when men were building canals across England, to compact the clay lining of the canal base they used to herd sheep through, in tern stamping the clay down.  If you do not own a herd of sheep, or know of a local flock, just use your feet to compress the loose top surface.  If you have very unstable soil, a compactor can be rented from a local depot.  

Now it is time to start thinking about the sand and cement mix.  
Many different websites will give differing advice but I have found success using  a dry mix of 'sharp' or 'builders' sand and cement in a ratio of  6:1.  

I didn't have a wheel barrow to mix in so I made use of the recycling bin.  It was just about large enough to easily mix one bag of sand with the cement, they were mixed until they changed colour. 

Apologies about the lack of pictures, I got carried away and in November the light goes before 4pm. 

I started in the closest right hand corner in the photo by laying a 1.5" thick layer of the pre-mixed cement in a square 4" wider than the size of the slab.   The slab was they laid in its final place and made level using a 5ft spirit level.  They were tapped home using a lead filled rubber mallet.  Be careful when tapping the slabs level as I managed to break one by tapping too vigorously.   My slabs protrude above the soil level by 0.5-1".  That was the easy one.  

Another load of cement was laid next to the first slab and the process repeated.  This time the slab must be made level relative to the first one.  Any adjustment can be made by lifting the slab, adding some cement in the right place, relaying and levelling.  
 It is very important that all of the slabs are as level as you can make them.  If they are textured slabs as mine are,  getting them 'level' is very difficult so try and ignore any  sharp high spots that could be 'absorbed' by the wooden beams under the floor.  

Repeat the process until you have a shed base.  The dry cement mix will eventually harden as it rains and moisture is soaked up from the soil.  Using the up-lighters from the living room, I managed to get 22 slabs down before I was forced inside by the dark and the cold.   The rest of the base was finished a few days later.