18×18 Outdoor Shelter Plans

This step by step diy woodworking project is about a 18×18 outdoor pavilion plans. I had a request for this large square shelter so I came up with these plans. This picnic shelter is easy to build and it features a simple but sturdy design. Take a look over the rest of our woodworking plans, if you want to get more building inspiration.

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. See all my Premium Plans HERE.



Projects made from these plans




18×18 Outdoor Shelter Plans




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  • A – 8 pieces of 6×6 lumber – 132″ long POSTS
  • B – 2 pieces of 6×6 lumber – 246 1/2″ long, 3 pieces – 216″ long TOP PLATES
  • C – 12 pieces of 6×6 lumber – 36″ long BRACES
  • D – 3 pieces of 6×6 lumber – 41″ long, 1 piece – 246 1/2″ long, 4 pieces – 34″ long TOP RIDGE

  • 12 pieces of 6×6 lumber – 12′
  • 3 pieces of 6×6 lumber – 22′
  • 3 pieces of 6×6 lumber – 18′
  • 5 1/2″ screws, 6 1/2″ screws
  • wood glue, stain/paint
  • post hole digger
  • post anchors
  • beam to post connectors
  • structural screws for connectors
  • strong tie T

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 Hammer, Tape measure, Framing square, Level

 Miter saw, Drill machinery, Screwdriver, Sander

 Safety Gloves, Safety Glasses

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 One day

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How to build a 18×18 pavilion



The first step of the project is to 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. Moreover measure the diagonals and make sure they 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.



Dig 3′ deep holes into the ground with a post hole digger. Align the holes with attention and then fit form tubes. Fit the 6×6 posts with attention and align them using string. Use a spirit level to plumb the posts and then lock them into place with temporarily braces. Fill the tube forms with concrete and let it dry out for a few days.



Use 6×6 lumber for the 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. Use 6×6 lumber for the other rails. Set the circular saw at 2 3/4″ and then make parallel cuts inside the marked areas. Clean the recess with a chisel and sandpaper.

Fitting the top rails

Fitting the top rails

Fit the top rails to the sides, to the front and to the back of the pavilion. Align the edges flush, making sure the corners are square, drill pilot holes and insert 6 1/2″ screws.

Fitting the braces to the frame

Fitting the braces to the frame

Build the braces for the front and back of the pavilion from 6×6 lumber. Use a miter saw to make 45 degree cuts to both ends of the braces. 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.



Use 6×6 lumber for the ridge beam. Mark the cut lines on the beam and then remove the excess with a chisel. Smooth the recess with sandpaper.

Fitting the ridge beam

Fitting the ridge beam

Fit the 6×6 supports to the top of the plates. Plumb the supports with a spirit level and then attach the top ridge. Make sure the corners are square and then insert 6 1/2″ screws.

Fitting the braces

Fitting the braces

Fit the braces to the top ridge. Cut both ends of the braces at 45 degrees and then secure them into place with 5 1/2″ screws.

How to build a 18x18 shelter

How to build a 18×18 shelter

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

18x18 picnic shelter plans

18×18 picnic shelter plans

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.



This woodworking project was about 18×18 outdoor 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.





  1. Mario Payan
    • Ovidiu

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