DIY Outdoor Sectional – Modular Design!


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July 28, 2023
Zoe Hunt

Have you been looking for the perfect outdoor sectional and have come up empty handed? Look no further! This DIY outdoor sectional plan features a modular design, so you unlock ultimate customization to create the perfect sectional for your space! 

Heck, if you didn’t want a sectional, you could even use these plans to create your dream outdoor seating set with armless chairs and a sofa. 

On top of being customizable, this modular sectional plan is beginner-friendly and very cost-effective for the size. 

DIY Modular Sectional on screened porch with white cushions

For our giant modular sectional, two tables, and a bonus piece so I could share additional configurations, we spent $400 on 6 sets of cushions and $250 on wood. This includes the wood required for both of the tables that are pictured with our sectional. 

Alright, let’s start DIYing and build this outdoor sectional!

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The height of each of the chair pieces is 26″. The depth is 30″.

The width of each of the chair pieces varies:

  • the armless chair piece is 28.5″ wide
  • corner piece is 30″ wide
  • one-armed chair pieces are 31″ wide

The ottoman is a 28.5″ square and 15.5″ tall with the cushion.

How to Build a Modular Outdoor Sectional

DIY customizable sectional sitting in garage workshop

In this post, we’ll talk through how to build a modular outdoor sectional. Since this DIY sectional plan is really composed of multiple individual plans, you’ll find more than one tutorial in this post. 

That said, there are several steps that are the same regardless of what specific piece of the sectional you’re building. We’ll share the instructions that are applicable to each piece and then in step 6, we’ll break it off into several tutorials. 

Once you complete the tutorial for each individual piece, head back to step 7 for the remainder of the tutorial that will apply to each piece. We designed it this way because it’s much easier to do some of the repetitive steps all at once. 

Want to DIY buy don\'t know where to start? Click here to grab your free guide!


Whether you’re building one piece, or twenty, the first step is always going to be to buy your cushions. It’s much easier to change the plans based on the cushions that to try to find the right cushions after you’ve already started building. 

We ordered two sets of these Segovia 3 Seater Outdoor Cushions from World Market. They tend to sell out fast, so if you want them, be sure to scoop them up as soon as you can! They are 28.74″ squares x 5.9″H. 

Though they are a pretty decent price for outdoor cushions and they look amazing, they are pretty stiff upon first sit! After sitting on them for a few days, they are starting to break in, but this is your warning that you’ll likely be disappointed the first time you sit on them.

Once you pick your cushions, you can start working on the cut list. We recommend making your pieces ⅛ – ¼” smaller than your cushion size. You want your cushions to be a tight fit so that they don’t move around or have gaps between them. 

In our printable plans, we include dimensions for the cushions we used as well as a spreadsheet that will auto-calculate the dimensions for you based on your cushion size.

Please note: We designed this outdoor sectional to sit on the lower side of standard couch, so if your cushions are shorter than 5.5-6” tall, you’ll likely want to adjust the height of the legs accordingly. This is automatically accounted for in the calculator that’s included with the printable plans.


Don’t worry, the beauty of a modular sectional is that you can switch things up whenever you want to, but you should decide on the number of pieces you would like to build and a general orientation so that you can build the right pieces. 

In this post we’ll cover how to build the main sectional pieces (a corner piece, an armless chair, an ottoman, and an end piece with an arm). Check out this post for how to build the outdoor storage table and see this post for how to build the table that slides nicely over the ottoman. 


Because this modular sectional is so customizable, we made a handy dandy cut list calculator that’s available in our printable plans. Instead of calculating how many pieces you’ll need of each size, you’ll just type in things like your cushion size and how many of each chair you want to build. It’ll spit out the cuts you need to make.

Once you have that, you can plop the number into this cut list optimizer to see the exact numbers of boards you need and how to cut them as efficiently as possible. 

As you’re selecting boards for this project, be sure to follow the guidelines in this post for selecting the best wood.

Free download wood sizing cheatsheet


Because we’re working with dimensional lumber here, you’re likely going to need to do a bit more sanding than you typically need to on other DIY projects. We find it significantly easier (and faster) to knock out the majority of our sanding before cutting anything down. 

sanding 2x3 board with Dewalt orbital sander

For our 2x3s and 2x2s, we started with 60 grit sandpaper and then quickly sanded them again with 80 and 120 grit. Since our 1x4s were in a bit better shape, we just sanded them with 120 grit sandpaper. 

Note: for indoor projects it’s generally recommended to sand to 220 grit. For outdoor projects, you really don’t want to sand beyond 120 grit to allow more of your stain or sealer to penetrate into the wood. 


Cut your wood down according to the optimized cut list. If you are confident in your ability to accurately measure and cut your wood, you can set up stops and cut all of the wood upfront. If not, we generally recommend cutting your wood as you go so that you can make adjustments as necessary if your cuts get off along the way. 


Using the 1.5” settings, add (2) pocket holes to either end the following boards: 

  • Front Stretchers 
  • Side Stretchers 
  • Back Stretchers 
  • Middle Supports

This is the same for every piece, regardless of whether it turns into an armless chair, and ottoman, a corner piece, or an end piece with one arm. 

Pocket holes are the foundation of most DIY furniture. Become a pocket hole pro in less than an hour in Pocket Holes: Explained.


This is the point of the tutorial where we’re going to break things down for each individual piece. Skip the ones you aren’t using and focus on the ones you do want to build. We’ll come back together at step 8 to complete each of the pieces the same way. 

Unless otherwise noted, all assembly is done with glue and 2.5” Kreg screws. 

Jump to: 

How to Build an Armless Chair 


Grab (2) short legs and a front stretcher piece. Attach them using glue and 2.5” Kreg screws. The top of the stretcher should be flush with the top of the short legs. 

front piece of armless chair made with 2x3s

Grab (2) long legs and (2) back stretcher pieces. Secure the first stretcher flush with the top of one of the legs using glue and 2.5” Kreg screws. 

Then grab your spacer board. Line it up with the bottom of the legs and then place the second back stretcher up against the spacer board. Yes, you could just measure, but when you’re building a lot of pieces, this spacer board is so much handier! 

Secure the stretcher with glue and 2.5” Kreg screws and then secure to the second long leg, making sure the top one is lined up with the top and the bottom one is lined up using the spacer.

back piece of DIY armless chair assembled with 2x3s and pocket holes

Grab (2) side stretcher pieces to attach the front and back to each other. First attach the side stretcher pieces to the front piece, making sure the legs are flush with the top of the short legs. 

add side stretcher pieces to front piece

The pocket holes should be facing inward so that they aren’t visible once assembled and should be flush with the outside of the legs. 

Next, position your back piece so that the pocket holes are facing up. With this orientation, the front facing pocket holes will be covered by the cushions and there will be no visible pocket holes from the front or back side. If you do not have back cushions, you may want to position the pocket holes towards the back of the chair instead. 

Clamp the spacer black to the bottom of one of the long legs. Flip the front piece onto the back piece so that the first side stretcher is flush with the outside of the long leg and the spacer block.

assembling DIY armless chair using spacing block to get correct distance from bottom of the leg

Attach using glue and 2.5” Kreg screws and then move the spacer block to the second leg and repeat. 

Head down to step 8 for the final steps of completing this arm chair. 

How to Build an End Piece with One Arm 

Whether you’re wanting to build a seat with an arm on the right side or the left, you’ll follow the same steps. Just decide which side you want the arm to go on before you start assembly. 


Grab one arm leg, one short leg, and one front stretcher piece to create the front of this single-armed chair. 

First decide which side you want the arm to be on. Place the arm leg on the side OPPOSITE of what you want it to be, then place your front stretcher piece with the pocket holes facing up towards you, and the short leg on the other side. 

Secure the stretcher to the short leg, making sure it’s flush from back/front and at the top. 

Then grab your spacer block and clamp it to the bottom of the arm leg piece. Secure the stretcher to the arm leg, making sure the bottom is flush with the top of the spacer block. 

using spacer block to line up front stretcher on leg

Grab one arm leg, one long leg, and a back stretcher piece. Lay it out so that the arm leg is on the side that you want it to be on (NOT the opposite side like in step 1). Place the long leg on the other side of the back stretcher that is laid out with the pocket holes facing up. 

front and back pieces of arm chair stacked on one another

Place the spacer block at the bottom of either leg and use it to guide the placement of the back stretcher piece. Secure with glue and 2.5” Kreg screws. Then secure to the other side after repositioning the spacer block on the second leg. 


Grab the two side stretchers and first secure them to the front piece. The top of the side stretcher should be flush with the top of the short leg. This side stretcher will be flush with the outside of the leg. 

The other side stretcher (the one between the two arm leg pieces) will be flush with the inside of the legs instead. This is so that you don’t see the slats when the cushions are placed on the chair. 

assembling chair with one arm for DIY sectional

To install the armrest, we’re going to use the same technique we used on these DIY chair and sofa plans

First, add some glue to the top of the arm legs. Then place the armrest on top of the legs, clamping it so that it’s flush on all sides. 

DIY outdoor chair with one arm sitting on garage floor

Mark ¾” from the front of the front leg, ¾” from the back of the back leg, and ¾” from either side. 

measuring 3/4" from front of arm rest with Kreg multi-mark tool

If you aren’t covering your screws with wood plugs, you can simply add screws at the 4 pieces where these lines intersect. 

If you are covering your screws with wood plugs, you’ll first drill a countersink hole that is ⅜” wide and about ½” deep

drilling countersink holes using Kreg quick-flip drill bit

Next, you’ll add your 2.5” wood screws. Add a dab of glue to the wood plug and place them over the screw head.


Now that the armrest is installed, we can install the final back support. This back support will be flush with the top of the armrest and long leg. 

We recommend positioning the pocket holes towards the front of the chair. Yes, it’ll look a little funky at first, but once you add the top cushion, you won’t have any visible pocket holes, even when looking at it from the back! 

installing back support for DIY sectional piece

Once you get the back support board installed, head over to step 8 to finish this piece up. 

How to Build a Corner Piece for a Sectional 

This corner piece is the same basic structure as the other pieces. Though it doesn’t require any complicated joinery, it is different from the other pieces because the legs are oriented in different directions. 


Grab a short leg, the front stretcher, and a long leg piece. 

Secure the front stretcher to the short leg, making sure it’s flush with the top and front of the leg. Rather than the leg being oriented flat as we’ve built all the other pieces, these legs will be on their sides so that the skinny side is visible.

Clamp the spacer block to the bottom of the long leg piece to guide what height to secure the front stretcher and secure so that the stretcher is flush with the front of the leg. 

assembling front of sectional corner piece

Grab two long legs and two back stretchers. This piece will be assembled similarly to the other chairs, with the legs being flat and the stretchers being flush with the front and the back of the legs.

The first back stretcher will be flush with the top of the legs. Use the spacer block to get the placement of the spacer on the other two legs.

back frame of corner modular sectional piece assembled on workbench

Grab 3 side stretchers. We first attached them to the back and then to the front, but it would probably make more sense to reverse the order considering the back is heavier. We’ll write it how we recommend doing it, but know that the pictures are the opposite order.

attaching side stretchers to back piece

Install the first side stretcher so that it’s flush with the top of the legs. Install the second side stretcher so that it’s 7” from the bottom of the legs (aka use the spacer block). 

Then secure the side stretchers to the back piece using glue and 2.5″ Kreg screws. The stretchers should be flush with the outside of the back legs.

DIY sectional corner piece being assembled in garage

Once all the side stretchers are attached, head down to step 8 to finish your corner sectional piece! 

installing final side stretcher to DIY corner sectional piece

How to Build an Ottoman/Chaise 

We used the same cushion for our ottoman as the rest of our seats. The accompanied back cushion just isn’t being used. World Market does sell a specific ottoman cushion, but it is a few inches larger. That’s not a problem, but if you want to use that, you’ll need to adjust the dimensions from the plans


Using glue and 2.5” Kreg screws, secure a leg to either end of a front stretcher. The top of the stretcher should be flush with the top of legs. 

Repeat with (2) more legs and the back stretcher. 

assembling front and back pieces of ottoman for DIY sectional

Note: if you aren’t sure which stretcher to use, it’s the longer of the two options for this piece. The side stretchers are longer than the front/back stretchers. 


Using glue and 2.5” Kreg screws, secure a side stretcher to each of the top corners of the front. All of the pocket holes should be facing inward so that they aren’t visible once everything is assembled. 

DIY ottoman base sitting on workbench in garage

Secure the side stretchers to the back piece. Continue to step 8 in the overarching project plan. 


One thing to note about this project is that it’s built with dimensional lumber. Even when you find the best boards there are, there’s likely still going to be a little bit of bowing/warping in some of your boards. 

You may find that some of your chairs seem wobbly or their feet aren’t all aligning exactly right on the floor. As long as you cut them to the same size, that’s okay. This next step will likely fix it. If it doesn’t, re-tighten the screws in each corner while applying pressure to the corners that are lifting up. Alright, let’s get to the next step. 

Mark ¾” from the top of the seat frame on both sides. Then mark ¾” from the top of the seat frame near the middle of the front/back pieces of the seat frame. 

Using glue and (3) 2.5” wood screws, secure a 2×2 support to either side of the chair frame. Line the top of the 2×2 up with the ¾” line you just drew. This will allow the slats to sit flush with the top of the seat. 

installing 2x2 supports boards to inside of sectional pieces

After installing both 2x2s, grab a 2×3 support board and install it using glue and 2.5” Kreg screws. You don’t need to measure and place it precisely, just make sure it’s straight so that it doesn’t make your chairs off-square. The top of the support board should be indented ¾” from the top of the seat. 

installing middle support board to bottom of DIY modular sectional chair


Apply the outdoor stain, sealer, or paint of your choice to protect your outdoor furniture. It’s important to use an exterior grade finish for outdoor projects, especially if you are using untreated pine like we did. 

modular outdoor sectional in garage workshop  before staining
DIY Modular Sectional Before Staining

For this project, we used Cabot Semi-Solid Stain in Taupe. It’s a great neutral color. No heavy undertones and it’s a light-medium brown.

As you’re staining, be sure to also stain the slats that haven’t been installed just yet. 

P.S. Each piece took me about 20-25 minutes to stain and I ended up using about a quart and a half on everything (both coffee tables included). 


Now that your pieces are all stained, we can install the slats. Place 6 slats on top of the bottom supports for each piece. 

No need to measure the spacing–it’ll be covered by cushions anyway. We placed the first and last piece about ½” from the front and back to allow for drainage if ever needed. Then we eyeballed the rest of the spacing 

Install using (6) 2” nails in each slat. 2 into each of the bottom support boards. 

nailing slats to bottom of DIY sectional to support the cushions


This DIY sectional is already ultra customizable, but we wanted to put one more customization idea in your head. You can add additional slats to the back and sides of the chair if you wish! 

If your cushions are a different size than ours, it might be a good idea to add an extra 2×3 or 2 to the back to prevent the cushion from falling through. Ours is nice and stiff, but I could see a floppy pillow struggling a bit more to keep up. 

how to make an outdoor sectional text overlay on image of dalmatian sitting on sectional with white cushions

There you have it! Now you know how to build your very own modular sectional. The question is…which orientation will you choose? 

Be sure to grab the printable plans to get access to the 3D renderings, and cut list calculator. Seriously, this cut list calculator might be the coolest tool I’ve ever made. I’m really excited about how easy it makes creating a custom cut list for this modular sectional! 

Now that you have your sectional built, be sure to check out the plans for the two accompanying tables. You can use them as coffee tables or sides tables or in any way your heart desires! 

Okay these next three plans weren’t technically designed for this particular sectional, but they would also be a great option to consider! 

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