---
title: "Deep Seating Cushions for Outdoor Sofas and Sectionals"
url: "https://cushionguide.com/cushions/deep-seating-cushions/"
section: "The Cushion Atlas"
author: "Callum Reid, The Weather Man of Casco Bay"
author_url: "https://cushionguide.com/masters/callum/"
published: "2026-09-13"
updated: "2026-09-13"
keywords: "deep seating cushions, outdoor sectional replacement cushions, patio sofa cushions, deep seat cushion set, outdoor loveseat cushions"
---

# Deep seating cushions: seat and back sets for patio sofas

*A deep seat is two cushions working as a pair. The seat fills the frame. The back stands on the seat. Size them together, from the frame, or the sofa never sits right.*

> **The quick answer:** Deep seating cushions are the seat-and-back pairs on outdoor lounge sofas, sectionals and club chairs. Measure the frame, not a standard: seat width inside the arms, depth front to back, and a back height equal to frame height minus seat thickness, so a 21 in frame with 4 in seats takes 17 in backs. Label every sectional piece on one drawing and order each seat and back separately.

![Ivory box cushions on a gray wicker patio sectional with navy striped and coral pillows beside hydrangea borders](https://cushionguide.com/media/outdoor-cushions/ivory-wicker-sectional-cushions-flagstone-garden-patio-1600.webp "Ivory seat and back cushions give a dark wicker sectional a clean outline, while navy and coral pillows carry the color.")

## Four frames, four depths, no standard

Four patio frames crossed our cutting table with seats 27.5, 28.5, 30 and 30.5 in deep (70, 72, 76 and 77 cm). Not one matched the next. That is the first lesson of **deep seating cushions**: there is no standard size, only your frame.

Deep seating is lounge furniture where a thick seat cushion and a separate back cushion work as a pair: outdoor sofas, loveseats, club chairs and sectionals in teak, aluminum or resin wicker. The seat fills the frame. The back stands on the seat and leans on the frame. Size one without the other and the pair fails.

This page covers sectionals and lounge sets. For benches, start with [outdoor cushions](https://cushionguide.com/cushions/outdoor-cushions/); for the whole backyard, [patio and porch cushions](https://cushionguide.com/cushions/patio-and-porch-cushions/). What does your frame measure at the back, friend?

## Measuring a deep seat frame, piece by piece

|   |   |
|---|---|
| Seat width | Inside the arms. Divide a long run evenly: a 67.5 in (171 cm) frame took three 22.5 in (57 cm) seats. |
| Seat depth | Frame front to back rail, inside: 27.5 in (70 cm) on that sofa. |
| Back height | Frame back height minus seat thickness: 21 in minus 4 in is a 17 in (43 cm) back. |
| Back width | One back per seat, as wide as the seat below it. |
| Thickness | Listed for every piece. 4 in (10 cm) is standard; thicker costs more. |
| Existing inserts | Seam to seam on the boxed side panel, nothing added. |
| Rounded corners | Size as if square, plus where each curve begins. |
| Extras | Ties, piping and a non-slip base, written in the order note. |

## Label the sectional before you measure it

Every piece gets a name on one drawing, left and right as you face the sofa.

| Piece | What to measure | from past orders |
|---|---|---|
| Corner seat | Both sides from the inside corner, then the depth | Corner seats 28.5 x 28.5 in (72 x 72 cm) |
| Armless seat | Width between its neighbors, and the depth | Side seats 28.5 in deep, 27.5 in wide (72 x 70 cm) |
| Seat between arms | Inside width divided evenly, and the depth | Three 22.5 x 27.5 x 4 in seats in a 67.5 in frame |
| Ottoman | Top length and width, and any rounded corners | An ottoman cushion with rounded corners, quoted with the set |
| Backs | Height above the seat, width per seat; corner backs must meet | Backs 16 in (41 cm) tall on the corner sectional |
| Large inserts | Seam to seam, plus where each curve starts | 76.5 x 30.5 x 5.5 in (194 x 77 x 14 cm) with rounded back corners |

## What keeps a back cushion standing

A back cushion has one job: stay upright while somebody leans on it.

- **Ties.** Sewn into the seams on request, at the corners or the back. Ties aren't standard, so ask in writing with position, length and color.
- **Double piping.** It stiffens a back enough to hold without straps. After seeing photos of one buyer's patio chairs, the workshop suggested double-piped backs instead of the straps on the order.
- **A wedge.** A back thicker at the bottom carries its weight low and leans into the frame.

A buyer in the US wrote from a windy yard: two 33 x 30 x 4 in (84 x 76 x 10 cm) seats, two 32 x 13 in (81 x 33 cm) backs made thicker at the bottom, and ties. A gust turns a loose cushion into a kite. Rain doesn't negotiate, and wind doesn't either.

Sleeve backs that slip over the frame? Ask the workshop before you plan around them. More in [back cushions that stay upright](https://cushionguide.com/guides/back-cushions-staying-upright/) and [backrest cushions](https://cushionguide.com/cushions/backrest-cushions/).

## Outdoor fabric, and what it will and won't do

The outdoor range runs to close to 200 fabrics on four or five charts: woven cloth, not vinyl, water-repellent, UV-resistant and fade-resistant, all one quality. The charts differ in texture, tone and pattern. Order samples from the [outdoor fabric Swatch Library](https://cushionguide.com/fabrics/outdoor-acrylic/) before you commit a whole sectional.

Water-repellent sheds a shower and a spilled glass. It is not sealed: seams and zippers let water in, and the foam has to dry out again. Covered patios and lanais suit these cushions best, and they come indoors for the off-season. A screened porch still gets pollen and damp air, so choose outdoor fabric there too, and skip tufting outside. The [water-repellent vs waterproof](https://cushionguide.com/guides/water-repellent-vs-waterproof-cushions/) Pattern draws the line.

The lead photo keeps it simple: ivory seats on dark resin wicker, with the stripes and the coral on the pillows. The slate blue teak sofa under the pergola splits its backs, one per seat, so each lifts indoors on its own.

## Foam, thickness and the dry-fast question

For garden armchairs the workshop recommends a 3 to 4 in (8 to 10 cm) seat of 32-density high-resilience foam, about 2.0 lb/ft³ (32 kg/m³), wrapped in polyester wadding. Deep seats run thicker when you want: real inserts on our table measured 4.25, 5.5 and 6 in (11, 14 and 15 cm), and sofa seats have been made up to 12 in (30 cm).

Seat and back needn't match. Many buyers choose a firmer, thicker seat and a softer or thinner back; one outdoor set paired about 4.75 in (12 cm) backs with firmer, about 3 in (8 cm) seats. Backs can be firm foam or pillow-filled.

Reticulated, or dry-fast, foam has open cells that drain water quickly. It isn't standard here, and neither is a mesh bottom, though a breathable mesh base has been built on request. If your seats will sit out uncovered, ask the workshop and get the answer in writing; the [dry-fast foam Pattern](https://cushionguide.com/guides/dry-fast-foam-outdoor-cushions/) explains when to insist. Try thicknesses in the [seat height calculator](https://cushionguide.com/studio/seat-height-calculator/).

## Ten covers over ten good inserts

A buyer in the US had an outdoor sectional with benches. The foam still sprang back; the covers were done. So the order was ten covers, piped and zipped, sewn to the inserts they already owned.

Seven measured 25 x 15.5 x 4.25 in (64 x 39 x 11 cm), one 47 x 15 x 5.5 in (119 x 38 x 14 cm), and two big ones 76.5 x 30.5 x 5.5 in (194 x 77 x 14 cm), with rounded back corners.

They measured the boxed side panel seam to seam and added nothing; a full insert crowns the top on its own. The workshop asked one question back: how far from each corner does the curve begin? That is the number people leave off.

Weigh covers against new cushions in the [patio replacement cushions Pattern](https://cushionguide.com/guides/patio-furniture-replacement-cushions/), and see nine more sets in the [patio set refresh sketches](https://cushionguide.com/concepts/patio-set-cushion-refresh/).

## Deep-seat mistakes that cost a second order

- ✗ Trusting a standard size. Our frames ran 27.5 to 30.5 in deep.
- ✗ Measuring the tired old cushion. The frame hasn't moved; the cushion has.
- ✗ Sizing the back to the full frame height. Subtract the seat first.
- ✗ Assuming one listing buys the pair. Each seat and each back is its own item; one buyer who missed that made three payments before the extra was refunded.
- ✗ Approving the drawing at a glance. One cushion arrived 23 in short, exactly as the approved drawing showed.
- ✗ Typing ties into the size box. Put extras in the order note, then look for them in the pre-shipment photo.
- ✗ Ordering covers for foam that stays down when pressed. Flat foam needs a full replacement.

> Deep seating cushions come in pairs: a seat that fills the frame, and a back sized to the frame height minus the seat. Measure the frame, never a standard.
>
> — Callum

> **Tailor's margin:** Photograph the bare sectional from above, then write corner, armless, arm end and ottoman on the print. One labeled photo beats ten emails.

## Deep-seat questions

**A common question:** The foam in my sectional is still good. Can I order just new covers?

**The workshop's answer:** Yes. Covers only, with no foam or filling, go through the custom zippered cover listing: pick the nearest size range and write each insert's exact length, width, thickness and fabric code in the personalization box, and each cover is sewn to fit snugly. Outdoor sectional covers are made this way, and extra-strong zippers can be requested. The workshop double-checks that you mean covers only.

**A common question:** Do the back cushions have to be as thick as the seat cushions?

**The workshop's answer:** No. Each cushion is its own item, so seat and back can match or differ. Many buyers pick a thicker, firmer seat with a thinner or softer back, such as 4 in backs on an 8 in seat, which also lowers the price. If a back rests on the seat, subtract the seat's thickness: a 17 in back on a 4 in seat fills a 21 in frame.

**A common question:** Where do I measure back height from: the frame or the top of the seat cushion?

**The workshop's answer:** From the top of the seat cushion, so the back rests on the seat, which looks and fits better. The seat takes up height: a 4 in (10 cm) seat with a 16 in (41 cm) back stands 20 in (51 cm) in all. Where space is tight the back can be shorter; one was made 15 in (38 cm) high.

**A common question:** What do you need to make seat and back cushions for my patio armchairs?

**The workshop's answer:** Not the chair's overall width, depth and height; those don't give a good fit. Send the width between the armrests, the seat depth, the back height you want and a photo of the chairs. For garden armchairs the workshop suggests a 3 to 4 in (8 to 10 cm) seat wrapped in polyester wadding, with ties at the back corners. Boxed and piped is no problem.

**A common question:** Can I add matching back cushions later, after the seats arrive?

**The workshop's answer:** Yes. Backs are made to any size in the seat's fabric, either firm foam, which holds its shape upright, or a soft filled pillow, which looks more relaxed. Order them with the seats, or later by quoting your original fabric code; one buyer added a back 90 in long, 11 in high and 3 in deep that way.

## Before you order the pair

### Is a deep seating set priced as a set or per piece?

Per piece. Each seat and each back is a separate cushion at its own size, and pillows styled in listing photos are sold separately. For a whole sectional, send one list with every piece and ask for the set to be quoted together; outdoor conversation sets have been quoted as a single bundle.

### Can deep seat cushions stay out through a rainy season?

Not uncovered. The outdoor fabric is water-repellent and UV-resistant, and the covers zip off to wash, but the foam isn't a quick-dry type and there's no drainage bottom as standard. These cushions do best on a covered patio or lanai and should come indoors for the off-season.

### Can a seat and its back cushion be joined together?

They can be made separate or connected so the pair folds. Separate is the usual build, and it lets you order a thinner or softer back than the seat. Say which you want in the order note, with the sizes of both pieces.

### Can outdoor deep seat cushions be tufted with buttons?

They can be made in outdoor fabric, but tufting lets water inside even then. For seats that get wet, beside a pool or a fire pit, the workshop recommends plain foam cushions without tufting, and its zippered outdoor versions are made without it.

## Related at the atelier

- [Adirondack chair cushions that follow the slope of the seat](https://cushionguide.com/guides/adirondack-chair-cushions/): Measure Adirondack chair cushions along the slats, not across the floor, taking six numbers: seat width at front and back, seat depth along the slope, back width at bottom and top, and back height…

*Fair winds — Callum*

---

Written by Callum Reid (https://cushionguide.com/masters/callum/) for CushionGuide (https://cushionguide.com/about/). The site explains made-to-measure cushions and the partner workshop makes them; measurements are in inches first. This Markdown mirrors the page at https://cushionguide.com/cushions/deep-seating-cushions/