A decent corner garden sofa will set you back £4,000 or more if you buy retail. I built this one over a weekend for around £2,000 using Iroko hardwood, and if you’re happy to use scaffold boards, you can get it done for closer to £500.
I designed it myself in SketchUp, ordered the timber cut to size, and built the whole thing in my back garden with no workshop. The result is a low-profile corner sofa and two coffee tables that fit our space perfectly and have held up beautifully since.
This guide walks you through the full build, with all the key dimensions and angles you need. I’ve also put together two downloadable plan packs if you want the complete cut list and 3D models to work from, one for the scaffold board version, one for the hardwood build.
Which Build Is Right For You?
There are two ways to tackle this project, depending on your budget and the finish you’re after.
The budget build uses scaffold boards. cheap, widely available, and easy to work with. It’s a great starting point if you’re new to woodworking or just want to see if you enjoy the process before committing to expensive timber. Total material cost comes in around £500. The downloadable plan pack includes a full cut list, step-by-step instructions, left and right-handed designs, and a SketchUp file.
The hardwood build is what you’re looking at in this guide. I used Iroko, a dense tropical hardwood with natural oils that make it genuinely suited to outdoor use. It costs around £2,000 in materials, but the finish is in a different league. The plan pack includes the full cut list and SketchUp file to work from.
Key Dimensions and Angles
Getting the proportions right is what separates a sofa that’s genuinely comfortable from one that looks good in photos but nobody wants to sit on. Here’s what I landed on after measuring our existing garden furniture and tweaking from there.
| Dimension | Measurement |
|---|---|
| Seat height (to top of wood) | 300mm |
| Seat height (with cushion) | 400mm |
| Backrest angle | 98° (8° off vertical) |
| Backrest height (from wood) | 405mm |
| Backrest height (from cushion) | 305mm |
The backrest angle is the one most people ask about. 98 degrees feels like nothing on paper, but makes a real difference in use, any more upright and it starts to feel like a dining chair. I cut all the angled pieces at 8 degrees on the mitre saw, which covers both the legs and the back supports.
Seat depth is something to think about carefully before you start. We went deep deliberately so you can properly lounge rather than perch. Check what cushion sizes are available before you finalise your dimensions and design around those custom cushions are expensive.
Designing the DIY corner sofa with CAD software
To help me visualise the overall design I used a free CAD design suite called Sketchup. It’s quite easy to use and helps draw the design for visual representation and detailed dimension. This helps when creating a cut list for all the materials. It also helps find the exact dimensions and angles for cutting.
Materials and Wood Choice
The most important decision before you start is the timber. Outdoor furniture takes a beating, so you need a wood that can handle moisture, UV, and temperature changes without warping or rotting.
For the hardwood build I went with Iroko. It’s a dense tropical hardwood with high natural oil content, which makes it resistant to moisture and fungal growth without needing heavy treatment. I chose it over Sapele and Utile because it’s lighter in colour and suited our garden better — we have a lot of oak around the house and Iroko sits well alongside it. I ordered it cut and planed to size from Woodshop Direct, which meant I could go straight into the build without any milling.
For the budget build scaffold boards are the way to go. They’re rough, characterful, and dirt cheap. You’ll need to sand them back properly and treat them well, but the end result can look great.
Protecting the Wood
Whatever timber you use, finishing it properly is non-negotiable outdoors. For the Iroko build I used Osmo Decking Oil applied with a lint-free cloth in several thin coats. It’s thinner than most oils, which means it actually penetrates exotic hardwoods rather than sitting on the surface. It keeps the natural colour while giving the wood a richer, slightly darkened finish.
For scaffold boards, a good exterior wood stain or decking oil will do the job.
How to Build a Modern Garden Sofa – A Step-by-Step Guide
Step 1. Prepare your area, tools and materials
Make sure you have plenty of space to complete this build. Clear you area and make sure you have somewhere dry to work.
Collect all your materials and lay them out on a flat surface. This will help prevent them from warping or moving. Give the wood a light sand all over before you get started. The planed all round wood will likely have sharp edges which should be smoothed beforehand.
Setup your workstation. I have used a small workbench and have setup my mitre saw for cutting the leg sections of this build. Almost all of the cuts for this project will be cut at 98 degrees. So I set my mitre saw to 8 degrees.
I’ve also installed a new blade on my mitre saw. I have used an 80- tooth cross cut blade which will give me perfectly smooth cross-cuts for this project. Here’s a look at how clean the cut is with this type of blade.
Step 2. Making the sofa legs
Using the following diagram, measure and cut the leg sections. There are two different types of legs for this project. 1. The legs for the coffee tables 2. The legs for the sofa
The coffee table legs
Using the following measurements, cut each piece to the correct length. Lightly sand each of the corners and sides to clear any splinters.
I then used a pocket hole system (Kreg Jig) to create two pocket holes for each join.
Whilst clamping the pieces together, insert and tighten the screws using my impact driver. I was careful not to over-tighten the joints as this can split the wood. It’s best to use hardwood screws (coarse thread) for this job.
I slowly work my way through each leg. It’s a good idea to apply some exterior wood glue to each join before securing the screws.
The sofa leg
These follow a very similar construction method to the coffee table legs with the difference in the tapered top section which I cut using my circular saw.
Here is how I cut the tapered section at the top. My circular saw wasn’t quite deep enough for this cut but I finished it off with a panels saw. Again, each piece was sanded before moving on to the next.
With each leg cut and joined, it was time to give them all a light sand with some 120-grit sandpaper.
This completes the leg building process.
Step 3. Building the coffee tables
For this step I lightly sanded each piece before continuing.
I laid all the pieces flat on the floor, selecting the nicest side to be the top of the coffee table. I then measured 150mm in from each side and centred the legs. Using 70mm (4mm) screws, I secured the legs to each piece of the top.
The screws are inserted from underneath so nothing is visible from the top. I drilled 3mm pilot holes before inserting the screws. To equally space out each board I used 4mm tile spacers.
This completes the coffee table construction. I have two coffee tables on this design.
Step 4. Building the sofa seat
The first task here was to measure and cut the cut out sections of the boards so that the legs and back supports can slot into place.
With the sections marked out I used a jigsaw, hammer and chisel to cut out the pieces.
Using 80mm screws, I joined the two corner legs and slotted the first piece into place.
I rolled the sections onto the back supports so that I could easily fix the planks from underneath. I added one board at a time and used the 4mm tile spacers for equal spacing between each board.
Repeat the above process for the other section of the sofa.
Step 5. Fixing the back supports
Without an extra pair of hands I made use of some F clamps for this part of the build. I marked out each board and held them in place with the clamps before securing them in place with some 40mm screws.
Each board was lightly sanded before I began.
This pretty much completes the build. Just two final steps left to finish and protect the wood.
Step 6. Sanding and staining the wood
The final stage of this build is to sand all the wood. I used an orbital sander for this job, starting with a 120 grit and then moving onto a 240 grit paper. Be sure to sand in the same direction as the grain of the wood so that any orbital marks don’t appear in the wood.
It’s then a good idea to wipe down the wood with a damp cloth before a final light sanding with a fine sanding foam pad.
Applying oil to exterior wood is important for several reasons. First and foremost, it helps to protect the wood from the damaging effects of exposure to the elements, including UV rays from the sun, moisture and temperature changes. Without protection, wood can become brittle, warped, cracked, and discoloured, which can compromise its structural integrity and aesthetic appeal.
By applying oil to exterior wood, you can help to prevent these issues and extend the life of the wood. The oil acts as a barrier that repels water and prevents it from soaking into the wood fibers, which can lead to rot and decay. It also helps to reduce the effects of UV radiation by blocking some of the sun’s harmful rays, which can cause the wood to fade and discolour over time.
Additionally, oiling exterior wood can enhance its natural beauty and bring out the richness of the grain pattern. This is particularly true for hardwoods like teak, iroko, or sapele, which have unique and striking grain patterns that can be accentuated with the right type of oil.
I’m applying several light coatings of an Osmo decking oil. It’s best to use a lint free cloth for this application, rather than a brush which can apply thicker layers which wont soak into the wood grain properly.
Step 7. Adding cushions to this diy outdoor sofa
It was quite difficult finding the right size cushions for our custom built garden sofa. This is something worth bearing in mind when designing your own sofa. Check what size cushions are available on the market and design the length and depth around these.
We were quoted over £900 for some custom-made cushions, which was a bit beyond our budget right now. Instead, we found some cheaper ones on eBay which are almost a perfect fit. Which was lucky. Here is the listing if you are interested: Garden sofa cushions eBay
To finish things off, I’ve stained the wood to protect it from the elements and added a few nice scatter cushions. The cushions are your basic 40x40cm, with cushion covers made from chenille fabric for a perfect match in colour and style to the rest of the garden. To protect the wood from hot drinks and spills, we’ve added a few patterned stone coasters, but we’re going to upgrade these to custom coasters to match the colour and styling of the garden.
Wood Options for Outdoor Use
If Iroko isn’t available or doesn’t suit your budget, Teak and Ipe are the best like-for-like alternatives; both are dense, naturally oily hardwoods that handle outdoor exposure well without heavy maintenance. Cedar and White Oak are worth considering if you want something more readily available from UK timber merchants. Whatever you choose, avoid untreated softwoods for anything left fully exposed to the elements. They’ll need regular maintenance and won’t last as long without it.
Tools Required
I built this with a fairly standard set of tools. Nothing specialist, but a mitre saw is close to essential for getting the angled cuts clean.
- Evolution mitre saw 210mm
- 80 tooth cross cut blade
- Dewalt Jigsaw
- Dewalt Circular saw
- Dewalt Orbital sander
- Dewalt Drill & impact driver set
- Kreg Jig
- Hammer
- Chisel
- Workbench
- Tape measure
- Sandpaper foam pads
Download the Plans
If you want to skip the measuring and go straight into the build, both plan packs are available below. The hardwood pack includes the full cut list and SketchUp file. The scaffold board pack includes the cut list, full instructions, left and right-handed designs, and a SketchUp file.
Download the Scaffold Board Plans
Download the Hardwood Iroko Plans
Final Thoughts
A bought corner garden sofa at this quality level costs upwards of £4,000. This one cost me £2,000 in hardwood, or you can build the scaffold board version for around £500. Either way, you end up with something that fits your space, suits your taste, and will outlast anything flat-packed.
If you don’t have a workshop, don’t let that put you off. Order your timber cut to size, wait for a dry weekend, and get started. If you do build one, share it in the comments. I’d genuinely like to see how it turns out.
