In the summer of 2020, my Mom and I decided to build a garden shed for outdoor bench. As the trees in our backyard had not grown tall enough to provide shade, we always wanted to create some shade to sit in at noon or chill in the summer evenings. We started with selecting which material is most accessible and easy to work with. Seeing the few spare PVC pipes in our garage from previous irrigation system repairs, we decided to give these a try.

The primary obstacle of using PVC pipes was to secure it such that they could hold up in extreme weather. As shown in the images here, our PVC shade is still holding up after 3 years of baking in the sun and enduring storms. Our rather peculiar choice of material, PVC, also contributed to why we built the shed with an arched top rather than a flat one. In the research process, guided by my mom, I also learned a little more about the physics of arched structures which I'm learning now in high school Physics classes! :)

Besides being a shade spot for benches, my mom also uses it as a greenhouse for seedlings and plants. We've enjoyed it for many purposes in the last three years.

The DIY Garden Shed is friendly to hands-on project enthusiasts of all ages and experience in building.

Supplies

Materials

12 pieces of .5" Rebar (48" in length)
3/4" PVC Pipes in the following lengths (see image below for more specifics of each piece):
(12 pieces of) 55"
(15 pieces of) 20"
(12 pieces of) 6.5"
(12 pieces of) 28.5"
6 pieces of 3/4" PVC Tee
12 pieces of 3/4" PVC Cross Tee
12 pieces of 135 Degree 3/4" PVC Elbow
A Roll of UV Blocking Shade Fabric Cloth
(optional = another layer of fabric) 10" x 12" Sun Shade Cloth with Grommets for Pergola Cover Canopy (12-Bungee Balls)
Zip Ties

Tools

3" x 9" x 24" Metal Fence Post Driver (or Post Pounder)
PVC Glue and Primer
Ratcheting PVC Cutter
Level Tool
Ladder

Step 1: The Design Process

Sketching the Idea

Making a shed with a flat roof would save material and effort, effectively cutting down the PVC connectors to only 12 pieces 90° elbow
However, knowing the physics of arch bridges, which was not common sense to me at the time, my mom proposed the arch roof.
Utilizing the limited flexibility of PVC pipes, the pipes should bend just enough to created an arch roof but still stay stiff and compact.

Why Arched?

After some research, I learned:

The advantage of an arch is most clearly seen in the arch bridge. As shown in Figure 2, as the force exerted on the bridge (by gravity and other weight) pushes down, the bricks compress each other and dissipate the force down until it is countered by the equal and opposite force from the ground (Newton's Third Law!). Thus, no one spot has to bear the concentrated force. This is the same for the roof of the shed.
If the roof were flat, however, buckling could happen where the compression forces eventually overcomes the bridge's ability to counter compression (Figure 1). As the material we had to work with were flexible PVC pipes, they do not resist compression as well as stiffer material like timber and concrete.

Source:

Kwong, Norman. "Physics of Bridges." University of British Columbia, https://phys420.phas.ubc.ca/p420_04/norman/physics_of_bridges.ppt. Accessed 25 June 2023.

Ashish. "Why Are Some Bridges Arched?" Science ABC, https://www.scienceabc.com/eyeopeners/ancient-bridges-arch-shaped-reason-abutment-load-distribution-strong.html. Accessed 25 June 2023.

Step 2: Making a Prototype

The actual dimensions of the shed ended up being 108" x 76.5" x 67" (L x W x H). I made the prototype in Fusion 360, in an attempt to model as close to the finished project as possible. The dimensions in the prototype is only for reference as the bending of the pipes required some trial and error to fit (will be explained in later steps).

To be more clear and concise, I will refer to each pipe part with the name and label number in () as shown in the first image above.

Video Animation of Assembly: https://www.youtube.com/watch?v=cxXbwxFKCtM

Step 3: Building the Foundation

"Post Pounder." Wikipedia, https://en.wikipedia.org/wiki/Post_pounder. Accessed 25 June 2023.

To begin, measure and mark the 12 points on the ground to hammer in the rebars. For reference, the width between the rebars on one side is around 21", and the distance between the two sides is about 76.5".
Once marked, use a post pounder or hammer to drive around 1/4 to 1/3 of the rebar into the ground. The rebars form the foundation for the rest of the structure, so should be kept as straight as possible using a level tool (I-Beam Level, etc).
With this dimension, the sun shed can fit a picnic table of dimensions 56.9" x 72" x 29.4" (L x W x H).

Step 4: Building the Sides

"Answer : How long should PVC pipe glue dry?" Deco Alert Magazine, https://decoalert.com/answer-how-long-should-pvc-pipe-glue-dry/, 25 June 2021. Accessed 25 June 2023.

Start building the following on one side, then repeat for the other:

After the rebars are all hammered into the ground, slip the 3/4" PVC base pipes onto each of the 12 rebars.
Glue on the Tee Connectors (5) on the two outermost Base pipes and Cross Tee Connectors (6) on the four Base pipes (1) in between. Make sure the connectors are facing the correct direction.
Starting with the outermost Tee Connector, glue in one end of the Horizontal pipe (2), then glue the other end to the Cross Tee Connector.

Also: The glue used for PVCs dry up very fast, which makes it more difficult to estimate the exact length required for the Horizontal pipes (2) connecting the Base pipes. Be careful of cutting the Horizontal pipes too long since the pipe fitting does not slide all the way in.

Glue in the Second from Base Pipe (4) for each connector.
Lastly, glue in the 135° elbow (7) facing the correct direction.

Step 5: Building the Top

On an empty ground nearby, make the roof separately:

Before cutting the pipes, make sure account into your calculations that the smaller top allows the roof to have bend upward like an arch. So the total width of the top connecting two sides should be smaller than the width between the two sides of Base pipes.
Cut out 12 pieces of Top Across pipes (3).
Glue the two Tee and four Cross Tee connectors onto the Top Across pipes and line them up in columns.
Finally cut out 5 Top Main pipes (2) and connect them to the above.

Step 6: Putting It Together: the (slightly) Tricky Step

Start by first attaching one side of the roof:

Also: This step may require help of one to two friends. And keep in mind the Top Main pipes (2) needs to be in the middle of the two sides to make the arch properly balance, so you may need to adjust the lengths as you go.

With one person on the ladder holding the roof, the other person can glue the 6 Top Across pipes (3) onto each of the 135° elbows. The person should keep holding the roof until the glue has completely dried.
After the glue has completely dried, bend the roof and glue the rest of the Top Across pipes into the 135° elbows on the other side. This step requires some force to insert the roof pipes. Make sure to hold the glued parts together until the glue has completely dried.

Build a Garden Shed From PVC Pipes - Step #6
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Step 7: Attaching the Cloth

We first attached a layer of sun shade cloth on the roof with zip ties.
Then, we made two curtain-like sun shade on both sides with each end wrapped onto another long pipe. By attaching only one end a little beneath the roof, we can adjust the curtains as needed.
To increase the shade during the summer, we added another sun cloth on top (final image).

Thank you for reading my Instructable!