CushionGuide

The Cutting Table · a question, worked through

Wedge, rectangular or curved: which back cushion supports a deep seat best?

A deep seat pushes your back a long way from the wall. A wedge brings the wall to you, and that is most of the story.

Pinned by Harlan

The quick answer

A wedge back cushion supports a deep lounging seat best, because its wider base gives your back more support than a flat rectangle. The workshop's standard wedge is about 35.5 in long and 15.75 in high (90 x 40 cm), 6 in (15 cm) thick at the bottom and 4 in (10 cm) at the top. One-piece curved backs are risky to fit.

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Key facts

  • Wedge backrests are recommended for deep lounging seats.
  • Standard wedge: about 35.5 in (90 cm) long and 15.75 in (40 cm) high, 6 in (15 cm) thick at the bottom and 4 in (10 cm) at the top.
  • A thicker ready wedge is about 8.75 in (22 cm) at the bottom and 6 in (15 cm) at the top.
  • A wedge that is wider at the bottom is the go-to for extra back support on a banquette.
  • One-piece curved or arched backs are risky: a small measuring error causes fitting problems.

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Foam
The core: its density and thickness set the feel.
Piping
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In inches: length × depth × thickness, plus any angles or cut corners.

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“My bench is deep. Wedge or rectangle?”

A wedge, my friend. On a deep lounging seat a flat back cushion leaves you leaning into empty air. A wedge is thicker at the bottom, and that wider base is where the extra back support comes from. The workshop recommends it for exactly that kind of seat.

It is also the shape the workshop reaches for when a banquette needs extra back support. The whole family of backs lives under backrest cushions, and the word itself is in the glossary.

“Could it be arched, to follow my wall?”

The workshop steers buyers away from it. A single curved back piece is very tricky: even a small measuring error causes fitting problems, and on a curve there is nowhere to hide the difference.

A seam is a promise, and a curve makes that promise harder to keep. A wedge that is wider at the bottom gives the support you were after, without betting the fit on one perfect measurement.

The two wedges on the table, and the shapes they replace

Back cushionBottomTopWorkshop's view
Standard wedge, 35.5 x 15.75 in (90 x 40 cm)6 in (15 cm)4 in (10 cm)Recommended for deep lounging seats
Thicker ready wedge8.75 in (22 cm)6 in (15 cm)The fuller version of the same shape
RectangularEvenEvenSame thickness top to bottom, so no extra support at the base
One-piece curvedVariesVariesSteered away from: a small measuring error spoils the fit

“And if I want my own numbers, 10 in at the bottom?”

Then send them. Buyers have asked for their own tapers; send the dimensions and the fabric, and the workshop quotes it. Foam backs hold their shape and stay put when wedge-shaped; pillow backs are softer and more relaxed. You can pair a firm foam seat with either.

The Pattern on back cushion fill goes further. How deep is your seat, front edge to wall?

A one-piece curved back cushion is very tricky to fit, because even a small measuring error causes fitting problems along the wall.

Harlan

Buyer questions

  1. A common question

    Can you make an arched or curved back cushion for my banquette?

    The workshop's answer

    A single curved back piece is very tricky, because even a small measuring error causes fitting problems. A back cushion that's wider at the bottom, wedge style, is a model the workshop makes often and gives excellent back support. Send dimensions and fabric for a quote.

  2. A common question

    Wedge or rectangular back cushion for a deep lounge bench?

    The workshop's answer

    Wedge. The standard one is 35.5 in (90 cm) long and 15.75 in (40 cm) high, 6 in (15 cm) thick at the bottom and 4 in (10 cm) at the top. A thicker ready version is 8.75 in (22 cm) at the bottom and 6 in (15 cm) at the top.

  3. A common question

    Should my back cushion be foam or soft like a pillow?

    The workshop's answer

    Either works. Foam backs hold their shape better, suit outdoor use and stay put when wedge-shaped; pillow backs are softer and more relaxed. A firm foam seat can be paired with a softer pillow back.

  4. A common question

    How do I keep a back cushion fixed to the wall?

    The workshop's answer

    With hook-and-loop tape: the workshop sews one side to the cushion and you fix the other to the wall with adhesive or screws. Back cushions can also hang from a rod on sewn-on fabric loops.

Questions buyers ask next

How long and tall is the standard wedge back cushion?

About 35.5 in (90 cm) long and 15.75 in (40 cm) high, tapering from 6 in (15 cm) thick at the bottom to 4 in (10 cm) at the top. For other sizes, send your dimensions and fabric for a quote.

Why does the workshop discourage one-piece curved backs?

Because a single arched or curved back piece is very tricky to fit. Even a small measuring error causes fitting problems, so a wedge that is wider at the bottom is the safer way to get strong back support.

Is there a fuller wedge than the standard one?

Yes. A thicker ready version measures about 8.75 in (22 cm) at the bottom and 6 in (15 cm) at the top, compared with 6 in (15 cm) and 4 in (10 cm) on the standard wedge.

How tall should the back cushion be on a deep-seat chair?

Take the height of the backrest frame and subtract the seat cushion's thickness, because the back sits on top of the seat. Replacement guides measure it that way, or simply measure a back cushion that already fits. Soft, fiber-filled backs with a 3 to 4 in side band plump up to about 6 to 8 in deep, so allow for that in the seat depth.

How thick should a deep-seat cushion be?

Deep-seat furniture usually takes a 4 to 6 in seat cushion, with 5 in the most common, often paired with a thinner back of about 3 in. The workshop's standard is 4 in and 5 in is a standard option; 6 in and thicker are made on request at extra cost. Measure the frame, not the old cushion, before choosing.