How to Build a Garden Workshop From Scratch

Building a garden workshop is one of the most rewarding DIY projects you can take on. Whether you want a wood workshop shed, a flat pack workshop, or a fully custom DIY garden workshop, this guide shows you how to build a workshop from the ground up, starting with the base and finishing with a complete, functional building.

In this guide, you will learn:

• How to build a workshop from scratch or using a flat pack workshop kit
• How to build a solid workshop base
• The full process from foundations to finished workshop
• Practical tips to make the build easy to accomplish
• Ideas for setting up the inside of your workshop

I built this garden workshop to support my woodworking hobby, which later grew into a small business. If you are also interested in a fully custom build, you can check out my complete guide here. How to build a shed from scratch.

Quick Summary: How to Build a Garden Workshop

• Choose the right location and workshop size
• Decide between a flat pack workshop or a custom build
• Build a solid workshop base using MOT Type 1 and paving slabs
• Assemble walls, roof, and floor panels
• Weatherproof and secure the workshop
• Fit out the inside with electrics, lighting, and workbenches

Workshop Location

I had a reasonable size space to work with for this project but decided to go for a 12 x 10ft garden building. This would allow me to leave a reasonable amount of space between the workshop and the garden boundary. I was tempted to squeeze in a couple of extra feet but this would leave it very close to my mulberry tree. It’s strongly advised not to build near trees or bushes as these over time can grow into the building and cause damage.

Once I had decided on the size, I needed to choose an actual building. Was I going to build this myself or save some time and buy a flat-pack one? On this occasion, I purchased a building from gardenbuildingsdirect.com, which (in my opinion) is one of the best websites for customisable garden buildings.

Building a Solid Workshop Base

So the building was on the way, but I needed some solid ground to put it on. I knew I had a few options here, but I had to consider what I could actually achieve on my own with the tools I had. I ended up going for a paving slab base.

A well-built base prevents movement, cracking, moisture ingress, and door misalignment. Taking extra time at this stage dramatically increases the lifespan of your garden workshop and avoids costly repairs later.

This would offer me a robust, strong and level base to build on. This part of the project was probably the most physically challenging, but it is actually quite easy in terms of skills required. I’d repaired some of the existing patio before, so I had a little experience, but never attempted anything of this size. Here’s how I did it.

How to Build a Workshop Base

Materials

For the base, there were a few materials required to ensure a good, strong surface for the shed to sit on.  These included:

• MOT Type 1 Sub base – This stuff is perfect for creating a solid surface to lay your slabs.  It consists of 1mm – 40mm jagged stones that compact down to form a strong level surface.
• General purpose cement – Combined/mixed with sharp sand to make your mortar mix (Concrete)
• Sharp sand – Mix with cement to make mortar.
• Paving slabs – I didn’t use anything fancy here, just a basic slab to support the shed.

Tools

To complete this base, you will need a few basic tools and one not so basic, the cement mixer.  You can try mixing the concrete by hand, but for the amount required, it’s much easier to buy or hire a cement mixer.

• Wheel barrow – Moving your materials around the garden
• Cement mixer – Mix the mortar.  I purchased one and now rent it out via Fat Llama
• Trowel – For applying the mortar to the base
• Shovel- Round edge shovels are ideal for digging into the MOT materials.  Flat edge shovels or spades are better for moving larger loads
• Compactor – I created my own out of a sledge hammer and an old slab but you can also buy or hire one
• Spirit level – The larger the better.
• Rubber mallet – to tap the slabs into place
• Tape measure – 8m is ideal
• String –  for marking out a level area
• Wooden pegs – for marking out a level area
• Gloves – hand protection

Step-by-Step gGuide for How to Create a Workshop Base

1. I started by marking out the area with some wooden pegs and string. Square this off by measuring from corner to corner until both lengths are the same.
2. Level out the area. This took a lot of digging and back pain but was essential to the overall build.  The overall area needs to be flat but also requires a bit of run off for surface water.  So don’t worry too much about levelling this perfectly.
3. Fill the area with the type 1 MOT and level off by walking over the whole space with tiny stomps steps. I used enough for about 60mm depth. In some cases you might need to go a little thicker but as my soil is mostly clay it wasn’t essential.  Clay is a very tough soil that hold weight well.  To calculate the amount of Type 1 MOT you require you can use this calculator.
4. As you can see I had a little help. 
5. I used a roller and makeshift compactor to create a nice flat surface.  I used a piece of wood and spirit level to get this as level as possible.  It’s important to compact the sub-base as much as possible to make sure the base doesn’t sink when all the extra weight is added after.
6. Mix up the concrete. I used a cement mixer because the thought of mixing all that in a wheelbarrow or mixing tray was very off putting. You can purchase one for about £230 or hire one for about £15 a day. The mix should be about 4 parts sand to 1 part cement. Water is added after to make a wet mix. There are plenty of YouTube videos to help if you get stuck.
7. Using a large blob in each corner of the slab and levelling off with a large spirit level. Each slab should have about a 6mm gap and level with the last. To get a nice level base you can use a long piece of wood to lay across the slabs and gently tabs each into place with a rubber mallet.
8. Ensure you follow the string line as you go along which should have a 2cm drop for every 1m.  This is to allow water run off.
9. Once all the slabs have been laid leave to go off for 12 – 24 hours. Now to fill the gaps. Simply mix some slightly damp sharp sand with some cement, about a 1 part cement to 2 or 3 part sand. Then using a scrapper push the mix into the gaps and level off with a small pipe or similar shaped tool.

That’s it for the base. Now onto the workshop. It was relatively easy to put this building together as the instructions were pretty clear.

Building a Prefabricated Workshop – Step-by-Step Guide

The instructions for assembling these prefabricated workshops are straightforward and easy to follow. To simplify the process of joining the panels, I utilised F-clamps, which served as an additional set of hands. It was crucial to ensure that the base was completely level, as this alignment was essential for the proper positioning of all the panels and roofing elements.

The base and walls were easy enough to erect. I had some rain which didn’t help but a large tarpaulin helped keep things dry.

There are a few key points to take note here to ensure a good sturdy build.

1. Ensure the base is completely level. Any slight unevenness will affect the way the walls and roof fit together.
2. Use two drills. One for drilling pilot holes and one for screwing. This will speed up the build.
3. When screwing the walls together, only use a couple of screw to start with as it’s very likely you will need to adjust each slightly.
4. I managed to build most of this on my own but there were a few times I required an extra hand. Thanks wifey 🙂
5. Check all the parts and arrange into piles before you start. This makes it easier to find everything and speeds up the build.
6. Don’t buy cheap drill bits from eBay. I went through a pack of 10 in two days!
7. Avoid rainy days. Ideal time to build would be in the summer. I was caught out by a couple of rainy days that prevented me from building. You can’t fit the roof materials when wet.
8. Think about what floor you want. I went for the cheaper floor on this model but wish I’d gone for the thicker flooring. This was about an extra £150 but I think it’s worth it. I added a cheap laminate floor just to strengthen it up a bit. This cost about £50.

So far, this is just a big space. The next stages for me to finish this project and make this a fully operational workshop will be:

1. Add some security. I won’t be putting anything in here until I’m happy it’s protected. I’ve purchased a decent smart home Yale alarm system, home security lighting and triple-bolted doors.
2. Workbench with storage. I’ve got some great ideas for a workbench I intend to build myself. Stay tuned for more on this.
3. Fit lighting and electrical points. Not too sure how this is going to pan out as I’m not a big fan of electricity as you can read in one of my other posts.
4. A suitable path. At the moment I just have some loose paving slabs laid in the grass but this isn’t ideal so I’d like to lay a proper path with a nice border.

Common Garden Workshop Mistakes to Avoid

I didn’t make this whole workshop without hitting a few snagging points. Here are a few of my top tips to ensure a smooth build.

• Building on an unlevel base
• Placing the workshop too close to trees or fences
• Skipping damp proof membrane
• Choosing flooring that is too thin
• Not planning electrics early

Estimating Total Costs for Your DIY Workshop Build

Here are some things to consider when estimating the total costs for your workshop:

• The size and scope of the workshop. How big will the workshop be? What features will it have? The more complex the workshop, the higher the costs will be.
• The labour costs. If you are hiring someone to build your workshop, you will need to factor in the labour costs. The labour costs will depend on the size and complexity of the workshop, as well as the hourly rates of the workers.
• The cost of tools and equipment. If you do not already own the tools and equipment you need to build your workshop, you will need to factor in the cost of purchasing them. The cost of tools and equipment can vary depending on the type and quality of tools you choose.

Insulating and Weatherproofing Your Workshop

Proper insulation and weatherproofing will make your garden workshop more comfortable, protect your tools, and extend the life of the building.

• Wall insulation options – Rigid foam boards, PIR insulation, or mineral wool slabs are all suitable choices depending on budget and wall depth.
• Roof insulation – Insulating between roof rafters helps retain heat in winter and reduces overheating in summer.
• Vapour barriers – A vapour control layer on the warm side of insulation helps prevent condensation and moisture buildup.
• External treatment or paint – Apply a quality exterior wood preservative or paint to protect against rot, UV damage, and moisture.
• Sealing gaps – Use exterior-grade sealant around doors, windows, and panel joints to prevent drafts and water ingress.

For a full step-by-step guide, see my detailed article on how to insulate a garden room, summer house, or shed

Conclusion

Building a garden workshop is a practical, achievable project that can completely transform how you work, create, and store your tools. I found that by taking the time to build a solid base, choosing the right workshop building, and assembling everything carefully, you can create a strong, long-lasting DIY garden workshop that suits your exact needs.

This workshop started as a simple space for my woodworking hobby and has since grown into a small working business space, which proves just how valuable a well-built workshop can be. Whether you decide to build a workshop from scratch or assemble a flat pack workshop, the same principles apply. Good preparation, accurate levelling, and patience during assembly make all the difference.

If you follow the steps in this guide, you will have a clear understanding of how to build a workshop from the ground up, including how to build a workshop base, assemble the structure, and plan the inside of your workshop. Take your time, measure carefully, and do not rush the foundation stage. It is the most important part of the entire build.

Once your garden workshop is up, you can gradually improve it with insulation, electrics, lighting, storage, and workbenches to turn it into a comfortable and productive workspace. A workshop does not need to be perfect from day one. It can evolve as your skills, projects, and requirements grow.

If you would like to explore a fully custom build, you can also check out my complete guide on how to build a shed from scratch, which walks through the entire process in more detail.