18×18 Pavilion Plans

Ovidiu 6 GapDice RANDOM PLAN

This step by step diy woodworking project is about a 18×18 outdoor gable pavilion plans. I had lots of requests for a 18×18 gable pavilion built on just 4 posts. This pavilion is sturdy and it features a beautiful design. Make sure you take a look over the local building codes, so you comply with the regulations. Take a look over the rest of our woodworking plans, if you want to get more building inspiration. Premium Plans for this project available Here. Check out the Shop, as well, for full list of Premium Plans.

When buying the lumber, you should select the planks with great care, making sure they are straight and without any visible flaws (cracks, knots, twists, decay). Investing in cedar or other weather resistant lumber is a good idea, as it will pay off on the long run. Use a spirit level to plumb and align the components, before inserting the galvanized screws, otherwise the project won’t have a symmetrical look. If you have all the materials and tools required for the project, you could get the job done in about a day.



Projects made from these plans




18×18 Pavilion – Free DIY Plans




Cut + Shopping List

  • A – 4 pieces of 8×8 lumber – 8 ft long POSTS
  • B – 2 pieces of 8×12 lumber – 22 ft long TOP PLATES
  • C – 2 pieces of 8×12 lumber – 18′ long TOP PLATES
  • D – 8 pieces 8×8 lumber – 36″ long BRACES
  • E – 2 pieces of 8×8 lumber – 42 3/4″ long, 1 piece of 8×12 lumber – 22″ long RIDGE BEAM
  • F – 2 pieces of 8×8 lumber – 48″ long BRACES


 Hammer, Tape measure, Framing square, Level

 Miter saw, Drill machinery, Screwdriver, Sander

 Safety Gloves, Safety Glasses


One week




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18×18 Pavilion Plans – Playing out

Laying out the posts

Laying out the posts

First, layout the posts for the 18×18 pavilion. Use batter boards and string to determine the location of the posts. Apply the 3-4-5 rule to every corner of the pavilion, so you make sure they are right angled. Make sure the diagonals are equal. Determining the location for the pavilion is essential, as you have to comply with the local building codes. Make sure the surface is level and remove the vegetation layer. Use 8×8 lumber for the posts. 

Anchoring the post into concrete

Anchoring the post into concrete

Dig 3 ft holes into the ground, making sure they have about 16″ in diameter. Fit the tubes then the posts into the ground and plumb them with a spirit level. Let the concrete dry out for several days. Read the local codes for more details on how to secure the posts. Install the anchors. 

Fit the posts to the anchors and plumb them with a spirit level. Use temporarily braces to make sure the posts are locked into placed while filling the holes with concrete. Use lag screws to secure the posts to the anchors. Before pouring the concrete you need to make sure the top of the posts are horizontal one to another. Use a laser to mark the level to the top of the posts and use a circular saw, if you need to make cuts.


Building the frame of the pavilion



Use 8×12 lumber for the top rails. Mark the cut lines on the beams and then make the cut outs with a circular saw and a chisel. Smooth the surface with sandpaper. Set the circular saw at 5 5/8″ and then make parallel cuts inside the marked areas. Clean the recess with a chisel and sandpaper.

Fitting the side plates

Fitting the side plates

Fit the top rails to the sides of the pavilion. Notice the 24″ overhangs to the front and back of the pavilion. Drill pilot holes through the plates and insert 10″ screws to lock them to the posts. Use 2 screws for each joint. Make sure the corners are square and plumb the posts vertically.



Fit the cross plates to the pavilion. Align the edges flush and drill pilot holes. Insert the 10″ screws to lock the cross plates into place tightly.


Attaching the braces



Build the braces for the front and back of the pavilion from 8×8 lumber. Use a miter saw to make 45 degree cuts to both ends of the braces.

Fitting the braces to pavilion frame

Fitting the braces to pavilion frame

Fit the braces to the posts, after you plumb them vertically. Drill pilot holes and insert 5 1/2″ screws to secure the braces into place tightly.


Fitting the ridge beam

Posts for ridge beam

Posts for ridge beam

Fit the 8×8 supports to the front and back of the pavilion. Use post to beam connectors to lock them into place tightly. Secure the connectors with 2 1/2″ structural screws. Plumb the posts with a spirit level before locking them into place.



Center the 8×8 supports to the top of pavilion. Plumb the supports with a spirit level. Use post to beam connectors to secure the supports to the frame of the pavilion. Fit the 8×12 ridge beam to the supports with post to beam connectors. Make sure the corners are square. Use 2 1/2″ structural screws to lock the connectors into place.

Braces for the ridge beam

Braces for the ridge beam

Use 8×8 lumber for the braces. Make 45 degree cuts at both ends of the braces. Secure the braces into place with 5 1/2″ screws. Drill pilot holes before inserting the screws,



Check out PART 2 of the project to learn how to build the gable roof.

How to build a 18x18 pavilion

How to build a 18×18 pavilion


18x18 pavilion plans - front view

18×18 pavilion plans – front view

Fill the holes with wood putty and let them dry out for a few hours. Smooth the surface with 100-220 grit sandpaper and remove the residues with a damp cloth.

Top Tip: Apply a few coats of paint or stain to the components, to enhance the look of the project. Premium Plans for this project available HERE. Check out the Shop, as well, for full list of Premium Plans.



This woodworking project was about 18×18 4 post pavilion plans free. If you want to see more outdoor plans, check out the rest of our step by step projects and follow the instructions to obtain a professional result.




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  1. Melodie Ritter at - Reply

    Good Evening,

    I’m looking for a Pavillion that is 24’x20′ with no center beams. I live out in the country and do not want to obscure my view. Do you have any plans for this size?

    Thank you,

    • Ovidiu at - Reply

      No. I have a search button and a list with all sizes available

  2. Leo Busch at - Reply

    I’m not understanding the size of the notch cuts for the top rails of the 18’x18’ pavilion plan which calls for a 5 5/8” and a 7 1/4 cut out. If using true dimensional 8”x12” lumber for the rails, shouldn’t the cut outs be 6” and 8” to accommodate true 8”x12” lumber? Please clarify.

    • Ovidiu at - Reply

      I always use actual dimensional lumber for all my plans. Therefore, I can’t redo the plans.

  3. Ed at - Reply

    Hi there, 8×8’s are tough to come by for the long 20 ft top rails. Could I substitute with three 2×8’s of southern pine at least for all the top rails/roof?

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