Gazebo Octagon 12'

These wood working plans include:

The following drawings: Front Elevation giving the dimensions of the unit; Foundation and Floor Plan; Gazebo Floor Plan; Roof Plan; Post Detail; details of the window openings and doors; detail of the hip and common rafters with dimensions; detail of the benches.

The plans have a List of Materials, showing a breakdown of materials for the gazebo floor, walls, benches, roof and fasteners.

The Instructions include directions on building the gazebo foundation, embedding wood posts or forming concrete posts, laying out an octagon, framing the walls, constructing the door and window opening trim, laying out and cutting the hip and common rafters, applying fascia trim and wood shingles and finally installing benches and fly screen.

Drawing of our octagon gazebo.

List of Materials

Gazebo Floor:

  • 6 - 2x6x12' beams
  • 2 - 2x6x8' beams
  • 10 - 2x6x12' joists
  • 64 - 2x4 x12' or 42 - 2x6x12' or 5/4x6 decking

Gazebo Walls:

  • 12 - 2x4x10' plates
  • 8 - 4x4x8' posts
  • 27 - 2x2x12' handrail pales
  • 4 - 1x4x10' door
  • 2 - 2x2x8' door
  • 2 - 2x2x10' door
  • 4 - 1x4x8' door
  • 2 - 1x6x8' door
  • 3- spring loaded screen door hinges
  • 1 - screen door latch
  • 1 - door pull
  • fly screen: 4' wide x40'; 3'x60'
  • 160' burlap molding or equivalent

Gazebo Benches:

  • 3 - 2x8x10' seats
  • 2 - 2x12x10' supports

Gazebo Roof:

  • 8 - 2x4x10' hip rafters
  • 4 - 2x4x10' common rafters
  • 2 - 2x4x10' blocking
  • 10 - mp24 mending plate
  • 4 - 2x4x12' fascia
  • 4 - 1x6x12' fascia board
  • 18 - 1x4x10' strapping
  • 215 - square feet shingles and caps


  • 6 lbs. #8 x 3" flat head wood screws
  • 4 lbs. 3" galvanized box nail
  • 3 lbs. 3" galvanized casing nails for the decking
  • 1 lb. 1" galvanized shingle nails
  • 3 lbs. 1 1/4" galvanized shingle nails
  • 1 lb. 2" galvanized box nails for the fascia board
  • 1 pint (500ml) carpenter's exterior wood glue


The Gazebo Foundation

I know you are allowed to embed pressure treated wood into concrete for decks and such down south. We are not allowed to do that in Canada and probably the wetter northern states. I have the building code for Fairfax County Virginia and they are allowed to do that with the following conditions: the 4x4s are pressure treated, the bottom of the hole is 24" below the grade and the post is up a minimum of 8" from the bottom of the concrete. The advantage to this is that you can dig a hole 16" square or 18" diameter by 24" deep, pour 16" of concrete in the hole, embed a 4x4 in the concrete about 8" up from the bottom of the hole. When the concrete dries you can accurately cut the tops of the 4x4s off to the correct level, at least 8" above grade.

The other option for the gazebo foundation, for our northern neighbors, is using 12" diameter sonotubes for forms coming up 8" above grade, finished off level. A steel strap is embedded in the top of the concrete to be nailed into the side of the beam. The same 2x6 beams are used except they should be pressure treated since they sit on the concrete or a layer of roofing felt or sill gasket is applied between the 2x6 and the concrete, to prevent rotting of the sill plate.

To layout the gazebo's foundation and floor, set up batter boards on the center lines as shown on the drawing. Refer to my article: How to Build a House 2: The Foundation.

The flooring should be either 2x4, 2x6 or 5/4x6 decking.

The gazebo walls will be framed right off the decking.

The Gazebo Floor

After the floor is installed it is time to layout the octagon shape.

The easiest way to layout an octagon is to cut the 8 sides, which are the 2x4 bottom plates. Cut each length to 1/16" under 5' with a 22 1/2 degree miter on each end. Cut one out first and use it as a pattern to cut out the others. When all 8 pieces are cut lay them out in position on the floor and measure across each end to be sure the opposite sides are parallel to each other (12'). Then use the pattern piece to cut out the remaining 8 for the top plates.

Fasten the bottom 2x4 plates to the gazebo floor in position with #8 x 3" flathead wood screws.

The Gazebo Walls

Cut 8 - 4x4s as corner posts 93" long. Fasten the corner posts on top of the plates so that the front face of the post is square with the 12' dimension of the octagon, as shown in the elevation drawing. Center the post over the miter joint.

Temporarily fasten the top plate into the same position on the 4x4 as was done on the bottom plate, in case adjustment is needed. Check to see that all the posts are plumb in both directions. Adjust as needed. Fasten securely with 3" screws through pre-drilled holes in the 2x4s.

Cut two 2x4 door lintels between the corner posts and fasten into position as shown on the gazebo's elevation drawing. Fasten the two sets of door posts between the lintel and the bottom plate. Do not cut out the bottom plate at the door opening. Since this is a screened in area, the screen door will close against the lintel at the top and the plate on the bottom.

Cut 2x2s to fit between the lintels and top plates in the gazebo's door openings. Use 3" screws to fasten them in place flush on the inside of the 2x4s. One screw pre-drilled in the lintel and plate should be good with a dab of exterior carpenter's wood glue. These 2x2s should not be more that 4" apart to match the handrail. Lay them out from the center each way. The screening will be installed on the inside, that is why we want everything flush on the inside.

Continue around the perimeter of the gazebo installing the lintels and 2x2s for the header as well as the 2x4 cap and 2x2s for the handrail. Keep these 2x2s flush with the inside of the lintels, plates and caps, as well.

The Gazebo's Windows and Doors

Cut the gazebo's window braces out of 2x6 stock to get about 3 1/2" wide arc. Install in place, as shown in Window Detail.

Build the door of the gazebo, as shown in Door Detail. The internal braces and center are made from 1x2. The frame is 1x4. Choose straight material for the door. Use biscuits and exterior wood glue for joining the frame and braces. If you don't have a biscuit cutter, rip a groove in the edge and make short splines out of scrap hardwood. If you have a dowel jig, go with dowels. Install the fly screen to the inside of the gazebo door. Install burlap molding over the edge of the screen to hold it in place, rather than relying on staples alone. The door should overlap the door posts, lintel and plate by 3/4" all around. Fasten the hinges to the door and install it. Rip down a 1x4 to fit and fasten it to both sides of the door posts, and mount the hinges and latch to this.

Before installing the gazebo roof rafters, it would be a smart precaution to apply mending plates on each intersection on the top plate on the walls. This helps tie everything together. Use Simpson Strong Tie #MP24 or equivalent. Just center the plate on the joint and nail the prongs into the 2x4.

The Gazebo Roof

The roof of the gazebo consists of 8 "hip" rafters and 8 "common" rafters. The common rafters shorten the span at the wall between the hips, as shown on the drawing.

Notice that the common rafter of the gazebo has an angle of 24 3/4 degrees and the hips have an angle of 22 1/2 degrees. There are 3 different lengths of Hip rafters, as shown: 2 at 84 1/2" the first two to install. Screw them together from the top with the 3" screws. Nail a mending plate across this first intersection on both sides of the rafters. Then 83 3/4" at right angles to the first two and nailed into them at the ridge with 2 - 3" toenails on each side. The third set is a compound plumb cut at 45 degrees on each side to fit nicely into the 90 degree corner formed from the first two sets of rafters. The gazebo's rafters are toenailed to the wall top plate with 2 - 3" nails on each side and into the blocking between the hips about 39" up from the wall line. After all the rafters of the gazebo are installed, cut and install the 2x4 fascia on the ends of the rafters to form the eaves of the gazebo. The fascia board is then nailed on, commonly 1x6 cedar. If a fascia gutter will be installed on the gazebo, eliminate the fascia board.

For wood shingles you need to strap the roof of the gazebo with 1x4 at the same exposure as the shingles. The exposure is different for the length of shingle as well as the grade. It should tell you on the package what the exposure is. The exposure is the amount of shingle exposed to the weather. The shingles are nailed about 1" in from each edge, none in the center, and about 1 1/2" under the exposure line. The nails should be centered on the strapping. Use a double course of shingles to start with at the eaves of the gazebo roof, overlapping the first course joints with the second. Overlap the shingle by at least 1 1/2". The caps on the hip are formed by alternating the way they overlap each other. Rip these caps from regular shingles about 6" wide.

The Screening and Benches of the Gazebo

Now that the roof is on, it is time to apply the fly screen and then install the gazebo benches as shown:

If you are unsure of anything in these drawings or instructions, send me an email for clarification.


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