Panel by Panel: My Hands-On Shed Building Adventure

When I decided to build a shed, I saw it as a perfect opportunity to put leftover CLT (cross-laminated timber) panels from my house construction to good use. They were already lying under the tarp for almost a year and I didn't want them to rot or make firewood from them.

I was really intimidated by the project at first, but it turned out to be more manageable than I thought. The hardest was the start. I learned a lot! From working with new materials to experimenting with 3D modeling and fighting with my fear of heights, every step of the way was a learning experience.

This article documents my process, from planning and construction to the lessons learned along the way. It’s not just a guide, but a reflection on the challenges and rewards of taking on a DIY project of this scale, especially when you’re not a professional builder. Hopefully, my experience will encourage you to dive into your own projects, whether it’s a small shed or something more ambitious.

Making Use of Leftover Materials

The main material for the shed came from leftover CLT panels, which had originally been used for my house. I had enough to use for the walls of the shed of the size 3 x 4m, and the dimensions were roughly 4.2 cm thick, 80 cm wide, and between 220 and 240 cm tall.

For the foundation, I used ground screws and wooden beams.

As for the tools, my toolbox isn’t very extensive, but it turned out to be enough. The main tools I relied on were:

• A circular saw, which I was initially intimidated by. Interestingly, the model I bought was so weak that it was almost incapable of kickback, which made it less scary to me.
• A Ryoba Seiun saku 270 (a Japanese pull saw) for fine cuts.
• Woodworking clamps to hold everything steady.
• A speed square for ensuring accurate cuts and angles.

For the floor, I opted for 22mm OSB boards and 18mm OSB boards for the roof.

For the roofing, I chose trapezoidal (corrugated) metal sheets, which offered durability and a good level of water resistance. Finally, I used a standard roofing membrane to protect OSB boards from condensation.

Planning and Modeling with Precision

Before any physical work began, I took the time to plan everything using SketchUp, a 3D modeling tool. Initially, I was quite intimidated by the idea of using 3D software. However, after watching just two YouTube videos, I picked up the basics and started to enjoy the process. Having the ability to experiment with panel arrangment and shed sizes was crucial to me.

The 3D model became invaluable later in the project. It allowed me to plan all my cuts in advance, get a clear idea of how the structure would come together, and make sure I wasn’t wasting any materials. Without it, I would have had to calculate and manually draw all the angles and measurements, which would have made the whole process much more time-consuming and prone to errors.

Laying a Solid Foundation

Once the planning was done, the next step was to lay the foundation. I decided to use ground screws and wooden beams. Ground screws were a practical choice, as they eliminated the need for concrete and provided a sturdy base while being easier to install on uneven ground. The beams were treated with a mixture of pine tar, tung oil, and turpentine to protect them from the elements. This traditional wood treatment not only sealed the wood against moisture but also gave the beams some insect-repellent properties.

The biggest challenge during this phase was getting the foundation both level and square. It took a lot of patience and small adjustments to make sure everything was aligned correctly. Any errors here would have caused bigger problems down the line, so I made sure to double-check all my measurements with a speed square and laser level before moving on.

Building a Strong Floor

With the foundation in place, I moved on to the floor. I chose 22mm OSB boards for this part. Then I started second guessing myself and did some research. I discovered that there's no right answer and it depends on your needs and how sturdy you want the floor to feel. Since the spacing between the foundation beams was about 90 cm, I decided to add some extra braces in between the beams to give the floor additional support.

Cutting and fitting the OSB boards was straightforward. The braces really helped strengthen the floor, and once everything was in place, it felt solid enough.

Cutting and Assembling the Panels

Once the floor was complete, the next step was cutting the CLT panels to size. This was where the 3D model truly came into play. Having everything pre-planned meant I could follow the dimensions and angles with precision, avoiding guesswork. Since I was working mostly during evenings after my regular day, the process was slow but steady. It took about two weeks of cutting in my free time to get all the panels sized properly.

After cutting, it was time to install the panels. I took some vacation days and, with help from my partner, started putting them up. The large panels were a breeze to manipulate with two people, and after a few hours, we had the main walls standing. It was incredibly satisfying to see the structure start taking shape.

The panels were secured to the floor and to each other with 140mm screws and galvanized connection plates, which helped ensure everything stayed firmly in place.

There was a small section of about 1 meter that I had to fill with off-cuts because there wasn’t enough large pannels. I used pieces around 30 cm wide to fill this gap.

Tackling the Rafters and Roof Frame

Once the walls were up, it was time to tackle the rafters and roof frame. I used the same spacing for the rafters as I had for the foundation beams — about 90 cm apart. However, one of the beams I had planned to use for the rafters was severely warped, so I couldn't use it. To get around this, I joined two shorter beams together, which worked out surprisingly well. This was actually my initial plan because I wanted to use the beams I already have but in order to make things quicker and easier I decided to just buy longer beams.

To fill the gaps between the rafters I used off-cuts from the CLT panels, not only to seal the building but also to help stabilize the walls. I had plenty of 140mm screws on hand, so I used those to secure everything tightly.

Constructing the Roof without Confidence

With the rafters in place things started to get challenging. The roof boards were significantly larger than the ones used for the floor(18 x 1250 x 2500 mm) and getting them up in one piece was not an option. I had cut them so that the boards were supported by the rafters. I then laid down a roofing membrane and installed metal sheets.

This phase was challenging due to my fear of heights, and I made a few decisions I might need to go back to in the future. For example, I overlapped the membrane edges instead of taping them, which should be fine on the sides and top edge but could need monitoring. Also I taped the membrane to the drip edge instead of the boards, this left the tape exposed to sunlight and OSB board edge exposed. So I had to tape over it to protect it from splashing water from the gutter.

Protecting and Preparing the Walls

With the roof in place, the next step was to protect the walls. Since I didn’t made the final decision on the cladding, I covered the walls with the same roofing membrane. This provides protection from the weather until I can install the final cladding. The plan is to use vertical slatted cladding.

There's always something more to do

The shed stands solid, and I’m looking forward to finishing the cladding soon. Also as you can see the membrane is not finished around the doorframe yet and I'm not really sure how to finish this detail. But the ultimate goal having a dry space for a lawnmower, bike and other stuff is finished.

Overall, building this lean-to shed was a huge learning experience. From mastering 3D modeling to handling CLT panels, every step taught me something new. While there were some mistakes—like the roof membrane choices and dealing with warped beams—it was all part of the learning curve.