Build an amazing shed – ground works

I thought that digging some holes and filling with concrete would be quick and easy. In fact it wasn’t hard but it did take a lot longer than I had expected.

The plan was to dig out holes approximately 450mm x 400mm x 400mm deep. Then concrete blocks laying on the top to achieve a height of 100mm above the highest point of the site. I dug the holes with help from a friend and decided to have a go at hand mixing the concrete. Each hole took about 75-100kg of ballast. I did 3 holes before giving in and hiring a mixer. Artisan tool hire are excellent and very cheap. It cost about 25 quid for the weekend.

The mix I used was 4 ballast to one cement. I used about 1.4 tons of ballast to fill the 12 holes. It was useful when mixing the concrete to accurately measure the ballast, cement, and water in a bucket. I used a stick as a depth gauge. 4 to 1 works out to be 4 builders buckets of ballast and half a 25kg bag of cement. Water was just under half a bucket. The actual amount of water will vary depending on how wet the ballast is.

The fall in height across the site is about 200mm even thought it looks flattish. To make my job easier I decided to pour concrete in the holes so that there would be two concrete blocks + a mortar gap to get to the building 100mm off the ground. This gave me enough wiggle room by varying the mortar thickness. Some holes needed filling above ground level. Where this happened I made some forms as shown in the picture below.


Here is another hole with less concrete and a strap to tie the shed down with.


Next step was to mortar the blocks in place. I set the first blocks at the highest point 100mm above ground and then made sure all the other blocks were at the same level.


As I was working I checked frequently that the blocks were all level in all directions. It turned out that a couple needed some packers, so I used old slates as these are thin and strong. Below is a photo showing the leveled blocks. I won’t be winning any prizes for bricklaying.


The next part will be to make the timber floor base from 4×2 timber.

Build an amazing shed – Design – part 2

After many sketches on envelopes and scraps of paper, image searches and arm waving, we have decided on the design for the workshed.

I have designed the shed using onshape. This is an online and free CAD tool. It is not as powerful as Sketchup but it is still amazing as it is browser based and has an android app. It was really useful to be able to work out what the shed would look like. It was especially useful to visualise the roof pitch and head-heights inside.

You can see the design here and even make copies for your own workshed.

Here are a couple of screen grabs of the design. Note the floor is not shown in these images but will be constructed as a suspended timber floor.



A few things about the design

Dimensions are 4×3 m with a total maximum height of just less than 2.5m

I didn’t really know what to do for the foundations. I asked builders, friends and the interweb with a variety of different suggestions. These ranged from 150mm concrete slab, paving slabs, timber bearers, concrete ring foundation, concrete piers and blank looks.

Local builders who did a lovely limestone extension for a neighbor suggested that pads would be sufficient. A poured concrete base just seemed like a lot of work, and not very environmentally friendly due to the environmental cost of cement production.

I have decided on:


  • Concrete piers/pads 400mm square. 12 placed equally spaced. Depth dug down to hard stony ground (350-400mm)
  • Concrete block on top of pier with wood frame on top.

Timber frame

  • A timber is raised above the ground by minimum 100mm and sits on damp proof course
  • Constructed from 100*50mm (2*4 in old money). At the moment I am uncertain whether to use treated CLS timber from a builders yard or treated rough sawn from the agricultural store. CLS is smooth and a regularised shape but is twice the cost. The rough sawn in splintery and not graded for strength but is ‘probably alright’.
  • Will be lined internally osb or ply for added strength and provide a surface to attach things to.
  • 900mm door to get bikes in and out easily


  • UPVC window as provide by a local skip to be repainted


  • Flat roof with 3 degree pitch or 150mm drop
  • To be covered by epdm membrane


  • Waney edge cladding, probably in cedar
  • Lined with breathable roofing felt

Next steps are the groundworks which might be a fancy way of saying hole digging.


Build an amazing shed – introduction – part 1

We have decided to replace the old shed that contains bikes, clutter and gardening bits with a bigger, better workshed. It will be a place to make, tinker, hide and be creative. I won’t say mancave, but others might. This is a lot to squeeze into the space available.

Here is a picture of the old shed and other garden clutter. We used to have chickens here, so there are no plants to remove. Note the herd of bins making a slow migration across the muddy tundra.


My partner and I have have different ideas about what should happen in the garden. I like making things and tinkering so would like a massive shed. She likes gardening so doesn’t want to loose garden space. Whilst I like the nice garden we have I am not motivated to spend my free time gardening. It actually works well, I chop stuff down and dig holes and she grows beautiful untidy wild looking plants

After looking at sheds online, in garden centers and specialist garden building companies we have decided to make our own.

One company worth a mention is Garden Affairs. They have some lovely high quality buildings well out of our price range. The owner was really nice when I went to visit them. They have provided the buildings at Hartley Farm

The design constraints are:

  • Must not look like a shed bought from B&Q
  • Must be less than 2.5m high to come within permitted development planning regulations
  • Must be less than 50% of the garden, again a permitted development thing
  • Actually it must be 4m x 3m as the agreed compromise between me (the shedman) and my partner (the gardener)
  • Constructed from wood
  • Clad in something nice
  • Be tall enough to store bikes stood on end
  • Be large enough to store bikes, garden stuff, and have a workbench
  • Would like to have power eventually

At the moment the budget is £2000, after it became apparent that £1000 would not cover it.

I will design it using onShape an online CAD tool a little like sketchup but completely cloud and browser based.

Here are some images for inspiration

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