How to Build a Circular Deck
A deck is a beautiful and practical addition to most homes when constructed with care. There are several designs that you can choose from, the circular deck being one of the most intriguing and probably the hardest to build. One of the special considerations when undertaking to build a circular deck is that the center support beam supports the majority of the entire unit’s weight.
Required Materials
- cement
- wood stock for beams
- wood screws
- metal fastening plates - flat, angle and T
- 1×8 treated board for stairs
- re-bar
Note: All wood must be treated to withstand outdoor conditions.
Required Tools
- table saw
- dado blade (to cut a 2”-wide block)
- drill
- philips drill bit
- hammer
- wheelbarrow (to mix cement in)
- shovel
- pencil
- measuring tape
- square
- 4 stakes - minimum
- string
Instructions
- Planning your Circular Deck - The first step is planning the design, size, and placement of your new deck. Use your stakes to mark the placement of the support and corner beams. This will give you a better idea of the support requirements and space accommodations necessary for your accessories.
- Placement of Your Footing – The deck will likely be a non-permanent structure. To alter this, you will need to place a 3’ length of principal support beam into cement. Consult your local library or hardware store for the desired support beam spacings. At the center of your circular deck place a round support beam which is at least 1” in diameter for every foot of the final deck. This is a pivot point as well as a main support. You will need to dig down to create a platform for your support beams. Where you plan to place them, dig an area that is no less than 4’ deep and 8” square. Fill with cement. Then set a length of re-bar into the cement so that 6-8” will be sticking up, and create a support stub. Drill a hole in one end of the beam to place the re-bar into.
- Forming Your Frame - Fasten a length of 4×4’ to the top of each outer beam to form the support frame. You may have chosen a design that requires the dado blade to make special cuts so that your frame fits together like a 3D jigsaw puzzle. You will need to make those cuts before constructing your support frame. A metal T-plate should be used to secure each of the supporting 4×4’s both to one another and to the supporting beams.
- Flooring Your Deck - Your design may call for either solid deck flooring or tongue-and-groove flooring (most experts do not recommend this type of flooring as it does not tend to last as long as the solid alternative). Use open flooring that can be easily made by securing 2×4” boards to the support frame with a 1/2” gap between each board. Countersink your screws to protect feet.
- Railing - When you make the special cuts in your supporting framework, you will also make special cuts for the top and fencing railings - make dovetail and groove cuts on all the pieces used for these rails. Place the rails according to your plans and secure the bottom of the fencing rails only. On the side of the support beams which face the fencing or lathing, place a long screw, leaving 3/6” of the screw exposed. With the top rail in place, you can attach a bungee cord to this screw, crisscross it over the rail tightly, and mark it. This will hold the other end of the bungee, helping to hold the rail and fencing in place as you work.
- The Stairs - Most professional plans call for a stair that graduates in 8” increments, but you could opt to use 6” increments to make access easier for young children and people with mobility problems. The extra 2” can make a big difference.
- Finishing - The last step is coating your deck. Some coatings are designed specifically for their visual effects, while others will be all-purpose. All-purpose coatings protect against extreme weather conditions, standing water, and snow, and also keep the wood from discoloring. You can either choose your stain color or opt for a clear coat. Whatever stain you choose, you should consider adding a bit of sand to the coating to help avoid slips and falls when the deck becomes wet.