What are cushion seam types?
Box edge, French seam, welt and tufting compared
The seam type describes how the top and bottom fabric panels of a cushion are joined at the edge. It decides the edge line, the cushion thickness that is possible at all, and whether the cover can be taken off later. This page explains which seam types we build, how to tell them apart and which one suits your furniture.
Why the seam type is more than a styling question
A cushion consists of a top panel, a bottom panel and the filling in between. How those two fabric surfaces meet at the edge is the seam type. Four things depend on it.
The edge line
A seam with a sewn-in side strip stands the edge upright and produces a straight, clearly drawn line. A seam without that strip tapers off and looks softer. Both are intentional, they simply suit different furniture.
The possible thickness
From roughly 4 cm cushion thickness upwards the edge needs a strip of its own, otherwise the seam pulls out of line and the cushion looks wavy. For thicker seat and back cushions the box edge seam is therefore construction, not taste.
Cleaning
A seam with a concealed zip lets the filling out, so the cover can then be cleaned according to the care instructions for that fabric. On a tufted cushion the stitching holds the filling in place and only the surface can be cleaned.
Your measurement
With a French seam the seam itself is part of the size you order and runs around the cushion at 2.5 cm. The cushion panel in the middle is therefore smaller than the width you entered. The worked example is further down this page.
The seam types we build
These are the options available when we make a cushion to measure. The welt is not a separate base construction but a box edge seam with additional piping worked into it.
| Seam type | Construction | Effect and use |
|---|---|---|
| Box edge seam | vertical fabric strip between the top and bottom panel | crisp edge line, factory-made look, needed from about 4 cm thickness |
| Box edge with welt | as above, plus a piping cord worked into the strip along the top and bottom | emphasises the edge, the welt is available in contrasting colours |
| French seam | no strip, top and bottom panel joined directly across the seam allowance | flat finish, looks handmade, suited to flatter cushions |
| Centre seam | a seam running down the middle of the cover | joins two widths of fabric or sits there as a design feature |
| Tufted | top and bottom stitched right through the filling, with thread or an upholstery button | breaks up the surface and holds the filling permanently in place |
Box edge seam and French seam side by side
These are the two base constructions you choose between in the configurator. The filling figures describe how we build them in our own workshop.
| Property | Box edge seam | French seam |
|---|---|---|
| Side strip | yes, as tall as the cushion is thick | no |
| Edge line | straight and crisply drawn | flat, softer finish |
| Look | factory-made | handmade |
| Recommended from | about 4 cm cushion thickness | flatter cushions and seat pads |
| Seam inside the ordered size | reflected in the thickness | 2.5 cm per side, contained in the size |
| Filling we use | foam core in the thickness ordered, wrapped in thermal fleece | 4 cm soft foam core, the rest built up with fleece on both sides |
The seam types on video
Both films were shot in our own workshop and show the differences on finished cushions rather than on a drawing. Please note that the commentary is in German, but the construction steps are easy to follow without it.
Box edge seam, French seam and welt next to each other: how the boxing strip stands the edge upright and how to tell the constructions apart on a finished cushion.
Tufting with thread and with upholstery buttons, single row and triple row, and what the stitching means for the filling and for cleaning later on.
What comes off and what stays on
This is the point that makes itself felt years later. It appears on no product photo, so it is spelled out here.
Box edge and welt come apart
These cushions are made with a concealed zip. The filling can be taken out and the cover then cleaned according to the care instructions for that particular fabric. Which fabrics go in a machine and which do not is set out in our care guide for outdoor cushions.
Tufted cushions stay together
On a tufted cushion the stitching holds the filling. The cover cannot be pulled off and cannot go in a washing machine. Stains are lifted with mild soapy water and a damp cloth, then rinsed off with clean water.
How closely we tuft
Up to a height or depth of 40 cm we tuft in a single row. From 41 cm the surface is tufted in three rows so the filling cannot shift across the larger area. From 8 cm thickness the filling sits inside a sewn fleece pocket.
Three mix-ups that keep coming up
In dressmaking a French seam encloses the raw edges inside a second seam. In cushion making the term describes the flat edge where top and bottom panel meet directly, without a boxing strip. English-speaking suppliers often call the same construction a knife edge. If you have seen knife edge cushions elsewhere, that is what we call a French seam.
The strip that stands the edge upright is the boxing, sometimes called a gusset. It is a component, not a third construction. There is no boxing without a box edge seam, because that strip is precisely what makes the seam a box edge. Depending on the product it is two side strips or one strip wrapping all the way round.
On a cushion the welt is a piping cord sewn into the edge to define it. In shading products the same German word describes a plastic bead along the hem of the fabric that slides into a keder rail on the wall. Same word, two entirely different parts. If you want to fit a keder rail, the shade sail pages are the right place, not the cushions.
What the seam type means for the size you order
Before you measure, three rules from our workshop are worth knowing. The full guide with diagrams is in our measurement instructions for cushions.
The French seam is inside your size
The French seam is 2.5 cm wide and runs around the cushion. It is not added to your measurement, it sits inside it. Worked example: order a width of 50 cm and the cushion panel is 45 cm wide, with 2.5 cm of seam on each side.
Thicknesses come in even steps
Foam cores are made at 4, 6, 8, 10 cm and onwards in steps of two up to 20 cm. Odd intermediate thicknesses cannot be cut directly, but can be approached by adding layers of fleece around the core. On angled special shapes 4 cm is often not workable, in which case 6 cm is the alternative.
One centimetre of tolerance
For cushions we work to a manufacturing tolerance of one centimetre. Measurement is taken corner to corner on the finished cover, without the filling inserted. A deviation within that tolerance is inherent to the making.
Frequently Asked Questions
Sources
- Custom cushions made to measure
- Measurement instructions for cushions
- Care guide for outdoor cushions
- All terms in the glossary
Last reviewed: 21.08.2026 · Reviewer: Germes-Team
Not sure which seam type suits your furniture?
Tell us what the cushion is for and how thick it should be. We will tell you which construction fits and which one will be easier to keep clean later.