First off, you need to get a gazebo plan from an authentic and experienced provider to design your gazebo. Numerous websites offer such gazebo plans on the internet free of cost. Pick one plan according to your preference and the available space in your garden. Make sure you take the accurate measurements for all the wood pieces before starting the construction.
Buy pre-cut wood from your local hardware shop or cut the wood yourself. Many hardware shops will cut wooden pieces in case they do not have the pieces that fit the measurement you need. The measurement will entirely depend on the gazebo blueprint you have chosen for construction.
Once you have decided the place where you will be making your wooden gazebo, you can start measuring the area where the foundation of your gazebo will rest. Dig approximate 30-inch deep holes using a posthole auger where each of the posts will go. The number of posts will be equivalent to the number of sides. Generally, they are six or eight in number.
Place the wooden posts in the holes and use concrete to set them. Use a spirit level to make the posts even and level. Support them with braces in order to help them stay in position while the concrete dries. Let the concrete dry for at least 24 hours before moving ahead with the construction.
Install the deck by connecting the plank to the post with decking screws. Make each plank even. Install the center deck post and joints from the center to the outside planks to build the deck base. Level each joist and screw them up inside the frame planks. Add cross supports between the joists and install the deck floor.
Build a concrete slab to extend about 2 inches past the length and width of the staircase and keep it about 4 inches thick to get support from the base of the steps. Measure the distance from one post to another post on the opposite side of the octagon. Cut the roof rafters equal to half this distance.
Nail two opposite rafters to a center point of the roof. Lift the truss to the top of building with the help of ropes and place the truss in place. Nail the cap plates into the appropriate posts. Attach rest of the rafters to the center point and corresponding posts.
Climb up on the roof and install tongue and groove joints for covering the rafters. Install asphalt roofing shingles with short roofing nails. Attach the rail sections to the ground posts using screws for the outside of your gazebo.