How to replace a patio chair sling

On an aluminum sling chair, the seat is one piece of fabric with a sewn hem down each side. A round vinyl cord, the spline, sits inside each hem, and the filled hem slides along a channel in the side rail of the frame. To replace the sling you free one rail, slide the new sling and its spline into both channels, then spread the rails back into place and bolt them. It takes an hour or two per chair.

Everything you need is on the project page for fixing outdoor patio chairs.

Is it a sling chair?

Look at the side rails. A sling chair has a slot running along the inside of each rail, with the fabric edge disappearing into it, and plastic end caps on the rail ends. Other chairs need other parts:

• Flat vinyl straps riveted around the frame: follow our guide to replacing vinyl straps.
• Vinyl cord wrapped around the frame: see restringing a patio chair with vinyl lacing.
• Fabric laced to the frame with elastic cord: see re-lacing a zero gravity chair.
• A sewn sleeve that slips over the rails, with no slot and no spline: that is a different kind of sling. This guide does not cover it.

What you need

• A new sling made to your measurements, or sling fabric if you are sewing your own
• Sling chair spline cord, unless the new sling comes with spline already in it
• A flat screwdriver for the end caps
• A wrench, socket or drill driver for the rail bolts
• A utility knife or scissors, and pliers
• A rubber mallet
• A cloth tape measure or a piece of string
• A spray bottle of water with a little dish soap
• A helper, or a spreading clamp or sling spreader tool

Step 1: Photograph and label

Take photos of the chair from the back and underneath before you undo anything. Mark the top of each rail with tape, and note the order of any washers and spacers on the bolts. Most chairs only go back together one way.

Step 2: Measure

Measure before the old sling comes out, while the frame is still square.

1. Width. Measure across between the slots of the two side rails, a few inches in from the top, and again a few inches in from the bottom. Many slings are wider at one end than the other.
2. Length. Run a cloth tape or a string along a rail, from the top to the bottom of the slot, following any curve. Leave the end caps out of it.
3. The old sling. Once it is out, lay it flat and measure it too. Old fabric stretches, so if the numbers differ, go by the frame. The old sling still tells you which end is the top and where any slits for bolts or bars belong.
4. The spline. Pull a short piece of the old cord out of the hem and measure it with calipers, or hold it against the smooth shanks of drill bits. Our spline comes in 3/16 in (about 4.8 mm), 7/32 in (about 5.6 mm) and 1/4 in (about 6.4 mm). If the old cord is gone, choose one a little larger than the slot opening, so the hem cannot pull out through it.

If a supplier is making the sling, ask exactly where they want the width taken and give them both sets of numbers. A sling only a little too narrow is very hard to fit; one too wide never gets tight.

Step 3: Take out the old sling

1. Pry the end caps off the rails with a flat screwdriver. Old caps are often brittle, so go gently and keep them; exact replacements can be hard to find.
2. Cut the old sling lengthwise down the middle with a utility knife.
3. Take out any cross bars or spreader bars that pass through the sling.
4. Slide each half out of its rail. Pliers help with a stubborn end. If it will not move, spray soapy water along the slot and give it a few minutes.
5. Unbolt one side rail completely and loosen the bolts on the other side rail part way, leaving it on the frame.

Step 4: Clean the slots

Run a rag or a thin brush through each slot to clear dirt, old fabric fibers and bits of broken spline. Feel for burrs at the slot ends and smooth them, so they do not snag the new hem.

Step 5: Put the spline in the hems

If the sling came without spline, cut two pieces a few inches longer than the hems. Warm the spline first, in the sun or under warm tap water, so it bends easily, then feed it through each hem. Push it in steadily, without twisting it or stretching the fabric edge.

Leave the new sling in the sun for a while too. Warm fabric is easier to work.

Step 6: Slide the sling into the rails

1. Mist the hem with soapy water.
2. Feed one hem into the slot of the rail that is still on the chair, top end at the top. Keep the hem straight and slide the sling along to the far end of the rail.
3. Slide the loose rail onto the other hem the same way.
4. Pull the sling until it sits evenly at both ends of both rails.

The mistake here is forcing a hem that has twisted. If it binds, pull it back out a little, straighten it and try again with more soapy water.

Step 7: Spread the rails and bolt them

1. Bolt the loose rail back onto the frame by hand, in its washers and spacers.
2. Spread the two rails apart until the bar holes and bolt holes line up. A helper can pull them apart by hand on a small chair; a spreading clamp or a sling spreader tool makes it much easier.
3. Fit the cross bars or spreader bars while the rails are held apart.
4. Tighten all the bolts.

This spreading is what puts the tension in the sling. Do not cut the sling or trim the spline until the frame is fully bolted and the sling looks right.

Step 8: Finish

Trim the extra spline flush with the rail ends with scissors or side cutters, then tap the end caps back in with the rubber mallet. Run your hand across the seat: it should be smooth and taut, with no wrinkles running toward the corners.

If it is still loose or will not fit

• Too loose: check that the spline fills the hem. A thin spline lets the hem creep in the slot, and the sling can pull out when someone sits down.
• Too tight to slide in: warm the sling, use more soap, and check that the spline is not too thick for the slot.
• Wrinkles: the sling is not centered on the rails. Loosen the bolts, slide it to even it up and tighten again.

For straps, rivets, lacing cord and elastic cords as well as spline, see the fix outdoor patio chairs project, or browse outdoor furniture repair.