What you need

Lumber sizes

A 2x4 is actually 1½″ × 3½″. Every measurement in this plan uses the real size. ¾″ plywood is drawn at full thickness, but plywood sold that way is often a hair thinner, so measure yours and cut the pieces that fit between panels to match.

Shopping list

112x4, 8 ftPressure-treated or cedar.
1¾″ plywood, 4 × 8 ft sheetExterior grade. The seat deck.
~403″ structural wood screws, exteriorSuch as GRK or Spax, for the frame and legs.
~903″ exterior deck screws
~102½″ exterior deck screws
~301⅝″ exterior deck screws
3Seat cushions, 24″ × 24″Plus back cushions.
1Exterior paint or stain

Tools

Miter saw or circular saw
Drill/driverWith a ½″ bit for the drain holes.
Level
Tape measure, speed square, pencil

Links for the hardware and tools ↓

Cut list

Twenty-eight pieces from eleven boards and one sheet. Label each piece with its letter in pencil as you cut it.

Part	Qty	Size, inches	From
ABack posts	4	1½ × 3½ × 28	2x4
BFront posts	2	1½ × 3½ × 23½	2x4
CEnd cross pieces	2	1½ × 3½ × 31	2x4
DFront and back rails	2	1½ × 3½ × 69	2x4
EMiddle cross pieces	2	1½ × 3½ × 24½	2x4
FMiddle front legs	2	1½ × 3½ × 12¾	2x4
GSeat deckSix ½″ drain holes.	1	¾ × 27½ × 72	¾″ plywood
HBack boards	3	1½ × 3½ × 75	2x4
IArm slats	8	1½ × 3½ × 31	2x4
JArm caps	2	1½ × 3½ × 26	2x4

Board layout. Each row is one board, cut left to right, with the remainder hatched. Dark lines are saw cuts, about ⅛″ wide.

Hardware & tools

Everything besides the lumber, with a link for each.

Links go to Amazon. Woodable earns a small commission at no cost to you.

Hardware

Seat cushions, 24″ × 24″Plus back cushions.3View on Amazon

Fasteners

3″ structural wood screws, exteriorSuch as GRK or Spax, for the frame and legs.~40View on Amazon
3″ exterior deck screws#9 or #10 × 3″, coated or stainless, rated for outdoor use and treated lumber.~90View on Amazon
2½″ exterior deck screws#9 or #10 × 2½″, coated or stainless, rated for outdoor use and treated lumber.~10View on Amazon
1⅝″ exterior deck screws#9 or #10 × 1⅝″, coated or stainless, rated for outdoor use and treated lumber.~30View on Amazon

Glue & finish

Exterior stain and sealerExterior stain or clear deck sealer.View on Amazon
Exterior paintExterior latex paint for wood.View on Amazon

Tools

Miter saw or circular saw10″ compound miter saw: square, angled and beveled crosscuts.View on Amazon
Drill/driverWith a ½″ bit for the drain holes.View on Amazon
Level24″ level.View on Amazon
Tape measure25 ft tape measure.View on Amazon
Speed square7″ rafter square for marking and guiding cuts.View on Amazon

Build it

Eight steps. The 3D view follows along as you scroll. The parts you're working on are yellow, and the pocket holes or screws for that step are red.

Step 1 of 8Cut the pieces

01
Cut the pieces
Measure your cushions first. This fits three 24″ × 24″ seat cushions between the arms, with room behind for back cushions. For other cushions, change the rails (D), back boards (H) and seat deck (G) by the same amount.
- A Back posts, four at 28″
- B Front posts, two at 23½″
- C End cross pieces, two at 31″
- D Front and back rails, two at 69″
- E Middle cross pieces, two at 24½″
- F Middle front legs, two at 12¾″
- G Seat deck, one at 27½″ × 72″
- H Back boards, three at 75″
- I Arm slats, eight at 31″
- J Arm caps, two at 26″
Drill six ½″ drain holes through the seat deck (G) so rain can't pool under the cushions.
02
Build the two arms
For each arm, lay a back post (A) and a front post (B) on a flat floor, 31″ apart at the outside, bottoms lined up. Screw the four arm slats (I) across them with 3″ deck screws, two into each post: the lowest one 3½″ up from the bottom, the rest 2″ apart, the top one flush with the top of the front post.

Build the second arm as a mirror image, so the slats end up on the outside of both arms.
03
Build the seat frame
Stand the front and back rails (D) on edge between the two end cross pieces (C): the front rail flush with the front ends, the back rail 3½″ in from the back ends. Drive two 3″ deck screws through each end cross piece into each rail.

Fit the two middle cross pieces (E) between the rails, centered 27″ and 51″ from the left end, and screw through the rails into them.
04
Join the arms to the frame
Stand the arms up, slats out, and set the seat frame between them with its top 12¾″ above the floor. Drive four 3″ structural screws through each end cross piece into each arm post.

Stand the two middle back posts (A) behind the back rail and the two middle front legs (F) behind the front rail, just outside the middle cross pieces. Drive two structural screws through the rails into each one, and two through the middle cross piece into each leg.

Watch outEvery leg and post must stand on the floor before you screw it, so all eight share the load.
05
Screw down the seat deck
Lay the seat deck (G) on the frame between the arms, its back edge against the back posts. Screw it down with 1⅝″ deck screws every 8″ or so into the rails and cross pieces.
06
Add the back
Stand the first back board (H) on edge on the seat deck, against the front of the four back posts, and screw it to each post with two 3″ deck screws. Add the other two above it with 2″ gaps. The top one ends flush with the tops of the posts.
07
Add the arm caps
Lay an arm cap (J) flat on each arm, flush with the outside and the front, its back end against the back. Drive two 2½″ deck screws into the front post and two into the top arm slat.
08
Finish
Round over the front edges of the arm caps and every corner people touch, and sand smooth. Seal the plywood edges well, then paint or stain the whole piece with an exterior finish.

TipUse outdoor cushions with quick-dry foam, and bring them in or tip them up after rain.
Get this hardware: Outdoor seat cushions, 24″ × 24″

Build safely

Build at your own risk. Check every measurement against your own lumber before you cut, test-fit before you glue, and wear eye and ear protection. Full disclaimer.