Scaffold corners and returns: how to plan and count them

What is a corner, a return and a corner bay?

A return is the part of a scaffold that turns from one face of a building onto the next. The corner is where the two runs meet. On a frame or modular system the runs are built as separate straight lines of bays, so the corner is a joint between two scaffolds rather than a special piece of scaffold. That joint has to do three things: keep a continuous working platform at full width, close any gap a person or a tool could fall through, and stay stable when the wind pushes on two faces at once.

There are two kinds of corner. An outside corner wraps around a building corner that points towards you; the scaffold is on the outside of the angle and has more length to cover than the walls themselves. An inside corner sits in a re-entrant angle, such as where an extension meets the main house; the scaffold is inside the angle, the two runs collide, and one of them has to stop short or be cut back with shorter bays or brackets.

How does an outside corner change the bay count?

The simplest outside corner lets one run, the corner owner, continue past the building corner by the scaffold width, so its last bay covers the end of the other run. The second run then starts against the inside face of that last bay. The owner’s run therefore needs to cover its wall length plus the scaffold width, and that can push it into an extra bay.

A worked example: with 0.73 m deep Blitz frames and 3.07 m bays, an 11.4 m wall needs 11.4 + 0.73 = 12.13 m of scaffold if it owns a corner, and four bays give 12.28 m. Alone, without a corner, it would still need four bays, because three give only 9.21 m. A 9 m wall is different: three bays (9.21 m) cover it alone, but as a corner owner it needs 9.73 m and goes to four bays. Whether a corner costs a bay depends on how close the wall already is to a whole number of bays.

The two runs do not share a frame line at an outside corner, because the frames of the two runs stand at right angles. That means each run keeps its own end frames and its own base jacks.

What does each system say about corners?

Layher Blitz

Layher’s Blitz instructions connect abutting bays at a corner with swivel couplers placed in the large openings of the node plates, with a further swivel coupler at the base, and the connected standards stand on a single base jack. For outside corners the frame is set projecting so the transition is as close to gapless as possible, and the top lift can be widened with swivelling and fixed brackets on one standard, with no height step between the decks (Layher Blitz instructions, 11.2013, chapter 8). For inside corners the frame is again set projecting; in the projecting bay, side protection is made with a telescopic guardrail and a toe board of matching length, or a 0.73 m bracket on the outside with a 1.57 m bay built across the end gives a level, closed transition, with gap covers at the joints.

The German approval adds two rules. Outside corners are built to its Annex C, page 22, or with corner decks to page 23, and the top levels have to be joined tension-proof, for example with locking pins, down to the next anchored level, so the wind cannot lift them. That uplift rule applies at buildings with inside corners and also at buildings with roofs pitched at 20° or less, so a flat-roofed building needs it on every run (DIBt Z-8.1-16.2, Annex B, B.1 and B.10).

Layher Allround

Allround is a modular system: standards with rosettes take ledgers in several directions, which gives more freedom at a corner. Layher’s instructions say to erect the scaffold starting from the outside corners, never to place equalising bays in the corner area, and to keep the full scaffold width round the corners. They show two basic layouts: four vertical standards with short decks in the corner, or two standards with longitudinal ledgers. If length has to be equalised across a corner, a rigid wedge head coupler connects the bay at right angles to the O-ledger; the gap between the two sections has to be closed, and in the projecting bay the side protection is built with tubes and couplers (Layher Allround instructions, edition 04.2018, chapter 15). The German approval for Allround, Z-8.22-64 of 23 April 2018, was extended on 5 April 2022 until 2 May 2027 (DIBt Z-8.22-64 extension.pdf)).

HAKI Universal

HAKI Universal is also a standard-and-ledger system, and its corner pieces are brackets. HAKI’s international user manual shows a 2-board corner bracket that is installed on top of the steel decks and fastened to the standard with its wedge coupler, and a 3-board corner bracket that must be installed on top of a 2-board corner bracket (HAKI Universal user’s manual, international version, 2022, page 18). The brackets fill the triangle of deck the two runs leave at the corner.

How do the counts change on a real house?

ScaFix’s system pages use the same example building for every system: 11.4 × 5.3 m with 4.5 m eaves and 6 m gables, scaffolded on all four sides. In the engine, each wall run carries one corner, so each run is its wall length plus the scaffold depth. With Blitz and Allround (3.07 m bays, 0.73 m deep) the long walls need 12.13 m and get four bays, the gables need 6.03 m and get two: twelve bays. With HAKI Universal (2.5 m bays, 1.01 m deep) the long walls need 12.41 m and get five bays, the gables need 6.31 m and get three: sixteen bays.

Base jacks

Bays on a closed ring would need only one frame line per bay if the corners were shared, but outside corners do not share, so every run adds one: sixteen lines for twelve Blitz bays, twenty standard pairs for sixteen HAKI bays. One caveat: the engine gives every frame line two base jacks, while Layher’s Blitz instructions let the joined corner standards stand on one jack, so a Blitz pick list can come out a little shorter at the corners.

End guardrails

Four separate walls would have eight unconnected ends; the ring has none. Instead each corner leaves one open face, where the end of one run sits inside the return of the other. On Blitz and Allround, with two deck levels, that is 4 × 2 = 8 end guardrails. The HAKI example lists 12. Its runs are laid out differently, five and three bays with a stair tower instead of ladder decks, and the engine guards every open deck end it finds in that layout; the HAKI Universal page shows where they sit.

Wall ties

The tie count follows each system’s own rule, not the corners. The Blitz approval’s 4 m continuous pattern ties every frame line every 4 m and also ties the standards of the top lift (DIBt Z-8.1-16.2, Annex B, B.5); Allround comes to the same 24 in the engine. HAKI’s manual asks for every inside standard to be tied at every 4th metre of height, with the lowest tie no higher than 4.8 m, and recommends anchoring as high as possible rather than adding a separate top-lift row (HAKI Universal user’s manual, page 32). On walls only 4.5 to 6 m high that gives HAKI fewer ties, 18 against 24.

The totals differ even more, 271 pieces for Blitz, 481 for Allround and 610 for HAKI at the same geometry, because a modular system lists standards, ledgers and transoms separately where a frame system has one frame, and because the HAKI example adds a stair tower and aluminium planks. The full lists are on the Layher Blitz, Layher Allround and HAKI Universal pages, and the house scaffolding guide walks through the same building.

How do UK tube and fitting scaffolds handle corners and returns?

In tube and fitting there are no corner pieces. A return is built from the same tubes, couplers and boards as the rest of the scaffold, so the count is a matter of logic rather than a kit list. We give no engine numbers here, because ScaFix’s generic tube-and-coupler model does not use UK tube and board lengths, but a British estimator counts a corner like this:

• Corner standards. At an outside corner the two lifts meet on a pair of corner standards, or one run’s ledgers are extended past the corner so the return’s ledgers can be coupled to them. Count the corner standards once, not once per elevation.
• Return transoms. Where the boards turn the corner, transoms run in both directions on the corner bay, so count the corner bay’s transoms in both directions, not just along the main run.
• Butting and bridging at inside corners. In a re-entrant corner one run is stopped short and its boards are bridged across or butted to the other run; the gap has to be closed so nothing can fall through.
• Boards round the corner. The working platform must stay at full width around the corner, so allow extra boards and toe boards for the corner bay and for any lapped boards.
• Ties and bracing. Ties and bracing for the returns follow the compliance sheet you build to, not the corner itself.

TG20:21 is the NASC’s good-practice guidance for tube and fitting scaffolding; its user guide explains how to read the compliance sheets, tie patterns and scaffold configurations (NASC TG20:21 user guide). HSE treats TG20 as the recognised standard configuration for tube and fitting, and anything not built to such a configuration must be designed by bespoke calculation by a competent person (HSE scaffolding guidance). Our TG20 guide explains how the compliance sheets work.

What do US rules say about corners?

OSHA has no corner clause as such, but three general rules decide what happens there. Platforms must be fully planked or decked between the front uprights and the guardrail supports, with gaps between units of no more than 1 inch unless the employer can show a wider gap is necessary; guardrails must be installed along all open sides and ends of platforms; and ties on scaffolds taller than four times their base width must be placed at each end and at horizontal intervals of no more than 30 feet (29 CFR 1926.451(b)(1), (c)(1)(ii) and (g)(4)(i)). The open face a corner leaves is one of those open ends, and the corner triangle is part of the platform that has to be decked.

What are the most common corner mistakes?

1. Counting walls as if they were separate. You double the end guardrails and miss the bay that a corner owner sometimes needs.
2. Putting short equalising bays at the corner. Allround’s instructions rule it out, and on any system it makes the corner harder to deck at full width.
3. Leaving the corner triangle open. Gap covers, corner decks or corner brackets are part of the order, not an afterthought.
4. Two jacks where the manual wants one. On Blitz the joined corner standards stand on a single base jack.
5. Forgetting uplift pinning. The Blitz approval asks for the top levels to be pinned down to the anchored level at inside corners and on buildings with roofs pitched at 20° or less.
6. Assuming the parts list covers the corner details. A planning list shows runs and ends; couplers, short tubes and brackets for the corner detail are chosen on site from the manual.

Plan corners before you fix the bay layout of each wall, and the rest of the count follows. The facade planning guide shows where corners sit in the overall plan. ScaFix models connected walls, corner ownership and return bays in 3D and lists the parts for many systems from wall dimensions or a PDF drawing; it is a planning tool, not a structural calculation.

This is planning information, not structural approval. The manufacturer’s assembly instructions and approvals decide how each corner is built, with HSE and TG20 guidance in Great Britain and 29 CFR 1926 Subpart L in the US, and a competent person must inspect the scaffold before use.

Frequently asked questions

Sources

Primary sources used for this article, with the date each was read.

• Layher Blitz Gerüst, Aufbau- und Verwendungsanleitung, edition 11.2013 (read 23 October 2026)
• DIBt Z-8.1-16.2: Layher Blitz Gerüst 70 Stahl (2 January 2025) (read 23 October 2026)
• Layher Allround Scaffolding, Instructions for Assembly and Use, edition 04.2018 (read 23 October 2026)
• DIBt Z-8.22-64: Layher Allround, extension of 5 April 2022.pdf) (read 23 October 2026)
• HAKI Universal User’s Manual, international version (2022) (read 23 October 2026)
• NASC: TG20:21 User Guide (read 23 October 2026)
• HSE: Scaffolding (read 23 October 2026)
• 29 CFR 1926.451, General requirements for scaffolds (govinfo, 2024 edition) (read 23 October 2026)