Slat Thickness | The Starting Point for Every Dimension
This series · The Changho Glossary · No. 15 (16 episodes total) Ongoing
"Sorting out the names and joinery of traditional changho, one at a time."
- No. 1 Jeongja-sal | A Changho Joined into the Character 井
- No. 2 Se-sal (細살) | A Changho Set with Fine Slats, Packed Close
- No. 3 Bit-sal | A Changho Joined with Slats Set on the Diagonal
- No. 4 Aja-sal | A Pattern With No Good Meaning
- No. 5 Wanja-sal | A Pattern Overflowing with Meaning
- No. 6 Sutdae-sal | A Changho Joined with Broken Slats
- No. 7 Semo-sotgeul-sal | A Changho Where the Cells Come Out as Triangles
- No. 8 Yukmo-sotgeul-sal | A Changho Where the Cells Come Out as Hexagons
- No. 9 Gyeokja-bit-sal | A Changho Layering Diagonal Lattice Over a Grid
- No. 10 Gwigap-sal | Tenon or Notch?
- No. 11 Yongja-sal | A Jeongja-sal Scaled Up
- No. 12 Changho Hung in Layers | Ssangchang, Yeongchang, Heukchang, Gapchang
- No. 13 Changho Built into the Wall | Bongchang, Salchang, Gwangchang, Deulchang
- No. 14 Small Changho | Baraji, Nukkup, Changgyeong
- No. 15 Slat Thickness | The Starting Point for Every Dimension
- No. 16 Finishing & Maintenance | What to Apply, and When to Redo It
Originally written in Korean and translated into English with the help of AI. Read the original
Window & Door Glossary — Joinery & Fabrication Series
Slat thickness is the very first number you fix when setting out a window or door's dimensions.
Jang Gi-in tabulated stile-and-rail width against slat thickness. Once the stile-and-rail is fixed, the tenon and groove follow it in turn.
Our windows and doors, in other words, start from the slat and grow outward.
Japan works the other way around.
The Meiji-era carpenter's manual Nihon Kaoku Kozo (1904) sets the stile-and-rail width of a temple gate door (karado) at 1/24–1/30 of the post spacing.
There, the bay of the building comes first, and the door is divided out of it.
The slats themselves differ too. The same book gives the visible width of an ordinary shoji slat as 2 bu 5 rin, about 7.6mm.
For a close-spaced shoji it goes down to 4.5mm. A shoji stands indoors; its slats never take wind or rain, so this is enough.
Our windows and doors are a different matter. Because the paper is pasted on the inside face, the slats sit exposed on the outside and take wind and rain directly.
Jang Gi-in starts slat thickness at 9mm, and records sutdae-sal or se-sal slats running past 20mm.
Even under the same word "slat," the job differs, so the thickness has to differ too.
Thickness and Width by Slat Type
| Slat type | Thickness (mm) | Width (mm) | Notes |
| wanja-sal / aja-sal (swastika / 亜 lattice) | 9–15 (usually 10.5 or 12) | 1.5–2× thickness | 12mm thick → 18–24mm wide |
| sutdae-sal (straight rod lattice) | 9–21 | 15–30 (up to 36 for large work) | |
| beom-sal | 9–21 | 15–30 (up to 36 for large work) | |
| se-sal (fine lattice) | 9–24 | stile thickness minus the chamfer | Fig.5-2 gives T = 12, 15, 18 |
| bit-sal (diagonal lattice) | — | 9–24 | width is the governing figure |
| maengjangji slats (opaque-paper door) | — | 15 and up to 45 | 15mm+ if spacing is under 15cm; 24mm+ if spacing is 20cm or more |
Dimensions That Follow From It
| Item | Basis | Notes |
| slat width | 1.5–2× slat thickness | wanja-/aja-sal |
| chamfer depth | 6–9mm | independent of slat thickness |
| stile-and-rail width | set by a table keyed to slat thickness | see Table 3-1 below |
| stile-and-rail thickness | 2/5–3/5 of the lintel thickness, usually 1/2 | usually 45–60mm; if the lintel is 75mm, use 2/5 or more |
| tenon thickness | 1/3–1/5 of stile-and-rail thickness | |
| half-lap width | 2/5–1/2 of slat width | se-sal crossing joints |
Wanja-/Aja-sal Stile-and-Rail Width (Table 3-1, mm)
| Slat thickness | Min | Typical | Max |
| 9 | 12 | 13.5 | 15 |
| 10.5 | 15 | 18 | 21 |
| 12 | 18 | 21 | 24 |
| 15 | 21 | 24 | 30 |
| 18 | 30 | 36 | 48 |
| 24 | 36 | 40 | 60 |
| 30 | 40 | 45 | 66 |
| 33 | 45 | 54 | 72 |
| 36 | 54 | 60 | — |
Se-sal Door Stile-and-Rail Width (Table 5-1, mm)
| Thickness | ×1 | ×1.2 | ×1.5 | ×1.7 | ×2 |
| 36 | 36 | 45 | 54 | 60 | 72(75) |
| 45 | 45 | 54 | 60 | 72(75) | 90(105) |
| 54 | 54 | 60 | 75 | 90 | 105 |
| 60 | 60 | 75 | 90 | 105 | 120 |
| 75 | 75 | 90 | 105 | 120 | 130(150) |
| 90 | 90 | 105 | 120 | 135(150) | 150(180) |
Bit-sal (Diagonal Lattice) Spacing (Table 2-1, mm)
| Slat width w | h/2 = 0.577w | h = 1.154w |
| 9 | 5.19 | 10.39 |
| 10.5 * | 5.77 | 11.55 |
| 12 | 6.93 | 13.86 |
| 15 | 8.66 | 17.31 |
| 18 | 10.39 | 20.77 |
| 20 | 11.55 | 23.09 |
| 24 | 13.86 | 27.71 |
Set at a 30° angle. Spacing runs 9–12cm for small work and 15–24cm for large work.
* The source prints 10.5, but the computed values 5.773 and 11.547 correspond to w = 10. Treated here as a misprint.
Sources
- 장기인, 『한국건축대계 I : 窓戶』, 보성각, 1983 / 2019 재판.
- 斎藤兵次郎, 『日本家屋構造』, 信友堂, 1904. 하권 참고편 「(三) 戸の部」「(四) 障子及襖の部」. 국립국회도서관 디지털 컬렉션 https://dl.ndl.go.jp/pid/846328
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