I volunteered to design and build a 22 foot diameter gazebo for Marsh Park in Fairbury, Illinois. This gazebo will be the centerpiece attraction for Marsh Park.
I did an Internet search, to try to find a picture of a gazebo design that I liked. I found this one........
For my Marsh Park gazebo, I did not want an elevated floor. I am already constructing a band stand, so there is no need to raise the gazebo floor for a band. I wanted to have the concrete floor at the same height as the adjoining sidewalks, so people can walk right through the gazebo. I also wanted to place 4 park benches inside the gazebo. Since the existing gazebo was 20 foot diameter in Central park, I wanted to have "bragging rights" to the biggest gazebo in town, so I arbitrarily chose a 22 foot diameter. The city maintenance crew prefers standard 3-tab shingles from a long-term maintenance perspective.............versus a wood shingle roof like our existing Central Park gazebo. I decided to use a color scheme of white for the gazebo, with red shingles.......similar to the picture I found of the gazebo I liked.
Our existing gazebo has about a 20 degree pitch. As best as I could tell from the image of the gazebo I liked, it was also about 20 degrees. Also, a 20 degree pitch is relatively easy to work on and shingle...........so I went with a 20 degree pitch on both the lower and upper roofs.
I wanted to used pressure-treated wood so the gazebo will last for many, many years. I chose 6x6 posts for the main supports, with a 2x6 horizontal board to connect the 8 posts. I wanted to use mostly 2x6 wood to make this a beefy looking design, versus 2x4's. The floor will eventually be concrete.
I used Google Sketchup to design the gazebo for Marsh Park. I had a lot of trouble designing the gazebo. I first tried putting all 8 posts in a north-south orientation, versus a radial orientation. The north-south orientation did not work when I went to copy the roof segments and rotate them around the vertical center of the gazebo. I ended up putting the posts in a radial orientation. It took me 3 attempts to get the roof designs done right.
Since the restroom was the highest elevation in the park, we wanted the concrete floor of the gazebo to be the same height as the restroom floors. We used a string and bubble level to determine the location of the gazebo.......needed the post holes dug to 30 inches depth.............so we would end up with 36" depth after adding the 6 inch thick concrete floor. We rented a post hole digger to dig the 8 holes. We laid out the holes using the known 22 foot outside diameter, and then the chord length between the posts. Then we placed the posts, we used the same methodology.
The above photo shows the pile of 16 foot long 6x6 pressure-treated posts we used to make the gazebo base. We sunk them 30 inches in the ground, because 6 more inches of concrete is going to be poured on top of that for the gazebo floor. I rented the post-hole digger from Ace hardware in Fairbury........
Here is the string layout I used to located the 8 holes for the posts. I used red spray paint as the marker for the post hole digger.
I used my dad's old manual post hole digger to clean the dirt from the post holes, after the post hole digger was retracted. This old auger could be 100 years old!! I am sure glad I did not have to dig hundreds of fence post holes like the old farmers did!!
We ended up making 2 rounds going around the circle of the 8 posts to get them aligned. The 1st round can be considered a rough location, and the 2nd round a fine-tuning location. We picked a home post on the east side, then worked 1/2 way around .............then went back to the home post and went around the other way. We were off about an 1" on the far post, but that was as good as we could get it. We used two 1x4's eight feet long at 45 degree angles to hold the posts in their proper location. After the posts were set, it looked like Fairbury had a wooden version of Stonehenge :)
We used my brother's tractor to lift up the 2x6 boards, so we could first screw them to the 6x6 posts using 2.5 inch deck screws. Later, I drilled and installed 1/2" diameter bolts to secure the 2x6's to the 6x6 posts.
It took me about 1 day to prime the structure with Zinser's primer, then another day to paint the finish coat of white latex. Those 96 columns, or 9 inch long pieces of 2x6, were sure a challenge to paint...........I had paint all over my right hand from getting all 4 sides of each cut-out!
I used Sketchup to design the decorative 45 degree arms for the lower gazebo base. The process I used to make the arms was.....
1. Design in Sketchup
2. Print full scale paper pattern from Sketchup
3. Glue paper pattern onto thin Luan plywood to make a wood pattern
4. Trace on the 2x8 pressure-treated wood
5. Band saw
These 45 degree arms are not only decorative, they also really stiffen up the whole structure from swaying.
I thought the key to getting the 8 pie-shaped roof pieces to all fit together well, was to make all of them exactly the same..........using an assembly fixture. I built the 1st pie in my garage because I had the desktop computer handy with the Sketchup design information.
I was very concerned the 8th piece would not fit properly into the gazebo, given the variation in wood used, and the large 22 foot diameter structure. I consulted with an old carpenter who has built many structures. We decided it would be wise to shorter the horizontal long bottom piece by 1/16 to 1/8" from the nominal measurement. This might help accommodate the variability you will have in this type of structure.
The lower horizontal piece of each pie segment has decorative grooves. It takes way too long to saw these using a saber saw in 1.5" thick pressure treated. I had to take each one home to my basement workshop, and cut them on the bandsaw. They were a bear to cut, because they are so long and heavy, even using a roller height stand to assist in carrying the weight.
Once I got the first pie segment to the park, I built the assembly fixture around it.......using scrap wood.
It took me 1.5 days to saw up all the pieces required to build the larger 8 pie shaped pieces. I found this little tool was very helpful, in checking angles for the compound angle cuts...
I also cut and nailed on the 1/2" thick pressure-treated plywood sheeting, while the pie pieces were in the assembly fixture. I did not put sheeting on the 8th piece, because I thought some field adjustment might be required. We then gave 1 coat of primer and 1 coat of finish paint to all 8 segments. We did not paint the top of the sheeting, because it will be covered with tar paper and red shingles.
When we lifted each segment into position, I wanted the inside of the segment to be a little higher than the final height needed, so we could lower it into place using the tractor. I did some trial and error testing using a come-a-long, to find the best lifting spot. I then installed some D-hooks rated at 1200 pounds at that spot. I estimate each pie segment weighed about 300 pounds.
Thinking through the final assembly sequence, once the pie segment was set on the gazebo base, gravity would cause the pie segment to want to slide down on the outer base 2x6. I decided to install 2 stop blocks on each pie segment to keep it from sliding out of position. I used Sketchup to determine where to place the blocks.
A gazebo roof does not become self-supporting until all 8 pie segments are installed. I decided to use two 2x4's, each 12 foot long to temporarily support each of the pie segments. These 2x4's will be used later as forms to pour sidewalks in the park. I placed them where the 8th and last segment would be installed, so they would be out of the way during assembly.
I lined up 4 other guys to help, for a total of 5 guys including myself. This turned out to be exactly the right number of guys for the job. The first challenge we had was that my brother's tractor was short about 1.5 inches of having enough lifting capacity. We solved that by placing some scrap 2x6's on the ground for the front tires of the tractor to drive up on. We placed the first segment in place, then attached the two long 2x4's to hold it up. We used a string across the top of the gazebo base, to set the height of the segment 19 inches higher than that.
When we got to the 2nd piece, we used two 6 inch bar clamps to get the upper 2x4's aligned, then put a screw in them to secure them. The bar clamps really worked slick one each following segment we installed. On the last and 8th segment, a miracle occurred, it slipped right into place with no field modifications required!! We did have to move some of the stop blocks when the segment was set into place, but we decided it was a good idea in general to use the stop blocks, and they became a permanent part of the gazebo.
Once all the segments were installed, I installed the stop blocks that we had to remove. I also drilled two 1/2" holes in each of the 8 joints, and bolted them together with 4.5" long 1/2 bolts.
I modified my assembly fixture to fit the smaller upper roof segments. It was easy to modify, because the 20 degree pitch angle was the same. It took me about one day to saw up all the 2x6 pieces needed to assemble the 8 upper roof segments.
I decided to paint the 40 pieces that make up the framing of the upper roof segments with a roller, before screwing them into roof segments. It took me about 6 hours to apply 1 coat of primer and 1 coat of finish paint.
Since my brother's tractor was out of lifting height capacity, we could not use it to set the upper roof segments into place. I climbed up on the finished 1st level roof and studied the situation. I came up with a solution for how to install them. I temporarily installed two of the long 12 foot 2x4's to the upper part of the lower level roof. One is to provide a place for the upper roof segment to rest on horizontally. The other 2x4 is to provide a place for my ladder to rest against. I pulled up the 1st segment using a rope. I was then able to slide it horizontally on the first 2x4. I placed my 24 foot extension ladder against the 2nd 2x4. I attached 2 scrap 8 foot 1x4's together to make a 16 foot long vertical support board. I then raised the upper roof segment until the 20 degree joint matched between the 1st and 2nd roof levels..........then I screwed the inside piece to the 16 foot riser. I had installed 2 screws as stop blocks at the 20 degree joint just prior to this.
I hoisted the upper roof segments using a rope to pull them up. After I installed #5 and #6 segments, I noticed the segments were no longer resting properly on the supporting 2x4's from the lower large roof segments. After checking measurements, I discovered what the problem was. I designed both the 1st and 2nd story roof segments to overhang about 6 inches on the outside. When I installed the upper roof segments, I aligned them from the inside of the gazebo up on the ladder..........and did not measure the resultant overhang. I got off about 2 inches on the overhang. So, I loosened up segments #5 and #6 and corrected the amount of overhang...........and everything lined up properly on the supporting 2x4's :)
On the 8th segment, the inside was about 1.5 inches high. I first hit it with a small sledge hammer, but did not budge it. I got a 12 inch pry bar, pried a little, and it snapped into place!!!!!!
The last thing to build was the cupola. I decided to break it up into about 4 different pieces, to keep the weight of each piece reasonable for rope hoisting them to the roofs. I had 3 guys on the ground push each piece up, then I took over with the rope and pulled them to the 1st roof. I used 1 inch oak dowels for the horizontal spindles on the cupola. I bought a new 1" auger bit from Ace hardware, and make a little fixture to hold the piece being drilled. I eyeballed the 45 degree drill angle, then checked the hole angle using a piece of dowel.
I worked from the top - down, and shingled the cupola first. I cut the standard ridge cap shingles in half horizontally, to scale to this small roof. I tried the standard size ridge cap, but it was too big. These are red maple, old 3-tab design shingles.
I used black roof sealant under the first ridge cap shingle, 8 places, to prevent high winds from tearing them off.
It took 4 calendar weeks plus 2 days from start-to-finish to build the gazebo. The concrete floor for the gazebo will probably be poured by the Fairbury City crew in the next few weeks. Here is the finished gazebo........
Number of Wood Pieces in the Gazebo
I made a spreadsheet to count up the total pieces of wood in this gazebo. I was surprised to see there are just under 500 pieces of wood in this gazebo !!
This was definitely a fun and challenging project. It took me 3 times to get the design right in Google Sketchup, before I started building it. Building the roof segments in a fixture turned out to be a great idea.........and helped to make sure all the roof segments fit together properly. Many thanks go to the "roof raising" crew and my brother, for helping to erect this gazebo!