How to Build a DIY Deck Lounger

This article appeared in the Summer 2022 issue of This Old House Magazine.

Recently, my husband and I realized our dream of putting in a swimming pool, which we surrounded with a composite deck. And since we ended up with lengths of leftover decking, I saw an opportunity to put them to use by building a pair of lounge chairs.

The design I came up with has backrests that fold down flat, angled legs for a modern look, and a long, slatted seat so we can put up our feet while watching the kids. The composite material does make the chairs quite heavy, but with corrosion-resistant fasteners and polyurethane glue holding the parts together, I’m happy to report that the chairs are strong and nearly maintenance-free. To make them perfect for relaxing, you’ll just need long cushions to cover the seat and the backrest.

Our lounge chairs beside the pool provide ideal vantage points for judging our kids’ cannonball competitions. Here’s how to build a set of your own

Note: The directions for this guide won’t include actual measurements so it will be important to find cushions, measure them, and design a frame that will work with them. For this design, Jenn bought chaise lounge cushions and built a frame to fit them.

Before You Begin

Composite decking material holds up great outdoors, but it has different characteristics than wood does. Here’s what you need to know when working with it:

1. To prevent composite faces from mushrooming around screwheads, drill a pilot hole for every screw.
2. Cut edges can be sharp, so round them over with a router or sandpaper.
3. If a cut exposes a composite’s core that doesn’t match its face, wipe the cut with a wood stain.
4. Composite decking expands and contracts with temperature changes. Leave 1/8- inch gaps at the ends of the slats.

TIP: Many kits are available for drilling and plugging screw holes in composite decking, but I found it much easier to just counterbore the pilot holes with a ¼-inch bit before popping in plugs.

DIY Deck Lounger Cut List

• Sides: 2 @ 4 by 79 inches (rip to remove one grooved edge for a final width of 4 inches)
• Ends: 2 @ 4 by 24 inches (rip to remove one grooved edge for a final width of 4 inches)
• Seat slats: 7 @ 5 1/2 by 22 inches
• Backrest slats: 5 @ 5 1/2 by 21 7/8 inches
• Legs: Rip grooves from both sides for a final width of 4 inches, then miter the ends of each
• leg at parallel 20° angles. Note the diagram to ensure the outside faces of each doubledup leg have a finished texture.
• Legs (outside front and back): 4 @ 4 by 9 1/2 inches
• Legs (inside front): 2 @ 4 by 12 43/64 inches
• Legs (inside back): 2 @ 4 by 11 5/64 inches
• Seat-slat side supports: 2 @ 1 1/2 by 9 1/8 inches (miter one end at 20°)
• Seat-slat side supports: 2 @ 1 1/2 by 32 1/8 inches (miter one end at 20°)
• End supports: 2 @ 1 1/2 by 12 inches
• Backrest support sides: 2 @ 1 1/2 by 33 inches
• Backrest support end: 1 @ 1 1/2 by 19 3/4 inches
• Backrest support arm sides: 2 @ 1 1/2 by 19 1/2 inches
• Backrest support arm end: 1 @ 1 1/2 by 17 3/4 inches
• Backrest support arm catch: 2 @ 1 1/2 by 5 inches
• Backrest support shelf: 2 @ 1 1/2 by 20 inchesTools

Steps for Building a DIY Deck Lounger

Step 1: Assemble the legs.

Following the cut list above, cut the decking to size using a table saw, then a miter saw. Apply polyurethane glue to the unfinished composite faces of one short and one long leg piece. Align their bottom edges, and clamp them until the glue cures. Drill four pilot holes through the long leg and into the shorter one; make a counterbore with a 1/4-inch bit, then secure with 15/8-inch screws. Conceal each hole with a plug. Do the same for the remaining legs.

Step 2: Attach the front legs.

Position the shoulders of the front legs against the bottom edges of the frame sides, 91/8 inches from the frame’s front end. Glue, clamp, and fasten them with 15/8-inch screws. Butt the seat-support rails on either side of each leg, grooved sides down. Using the same screws, glue, clamp, and fasten the rails to the frames’ sides and ends, 1 inch below its top edges.

Step 3: Attach the back legs.

To allow the backrest to lie flat on the back legs, trim their shoulders by the thickness of the backrest support. Then glue and screw each leg 11 inches from the frame’s ends.

Step 4: Prep the supports.

Position the backrest supports 1 inch from the installed seat-support rails. Drill a 3/8-inch hole through the parts 1 inch from the end of the backrest rail.

Step 5: Assemble the frame.

Set the sides and ends of the chair frame on their flat edges, perpendicular to each other. Drill two pilot holes through each end board and into the sides. Fasten the pieces with glue and 3-inch screws; conceal the screws with plugs. Glue and screw the support-rail pieces to the inside of each frame end.

Step 6: Attach the backrest support arms.

Hammer a carriage bolt through the outside of each frame piece and each backrest support arm. Embed the bolt heads in the composite. Add washers, then tighten a locking nut onto each bolt with a wrench.

Step 7: Secure the seat slats.

Set the first slat against the frame’s front end, then glue and screw it and six other slats to the fixed rails. Affix the slats’ ends with glue and two screws, leaving a 1-inch gap between them. Assemble a U-shaped frame for the backrest. Set it on the back legs, then glue and screw the remaining slats to the frame.

Step 8: Support the backrest.

Screw together two 5-inch-wide boards to make an L-shaped shelf to elevate the backrest; fasten the shelf between the back legs. Make a U-shaped arm with glue, 3-inch screws, and three lengths of stock; bolt it to the frame. Now screw doubled-up blocks to the inside of the frame to cradle the backrest when lying flat.

Add the cushions and enjoy!

Materials

• 100-grit sandpaper
• Clamps
• Four 1 x 6 x 12 composite deck boards
• Polyurethane glue
• 1 5/8-inch-trim head deck screws
• 3-inch trim-head deck screws
• Composite plugs
• Two 3/8-by-2 1/2-inch stainless steel carriage bolts, washers, and locking nuts
• 3/8-inch deck plugs
• Lounge cushions

Tools