Glossary

Scaffold, fence and plan terms

The words you meet in our tutorials and on the plans, explained simply. Standards are Canadian and cited by edition and article.

The scaffold

Bay: Space between two adjacent standards or frames, along the length of the scaffold. A scaffold's length is always made of whole bays.
Lift: Height between two levels of the scaffold. For a stair, height climbed by one flight.
Standard: Vertical load-bearing tube. It carries the loads down to the screw jack and the sole plate.
Frame: Prefabricated unit of two standards joined by cross members. Frames are stacked to build the scaffold up.
Cross brace: Pair of crossed tubes between two frames that braces the scaffold.
Platform: Working or access surface of the scaffold, made of decks.
Deck: Prefabricated platform unit set between two ledgers or frame bearers.
Hatch deck: Deck with a hatch that lets the access ladder pass from one level to the next. Scaffold places one at every lift of the access bay.
Guardrail: Fall protection at the edge of a platform: top rail, mid-rail and toeboard.
Toeboard: Board set on edge at the platform edge, which stops objects from falling.
Screw jack: Adjustable threaded base under a standard, used to level the scaffold.
Sole plate: Timber piece under the screw jack that spreads the load on the ground. A scaffold's footprint includes its sole plates.
Tie: Connection of the scaffold to the wall or structure, which holds it against overturning and wind. Each tie needs a pull-out test before installation.
Wall gap: Distance between the edge of the platform and the wall. A platform more than 350 mm from the wall needs a guardrail on the wall side (CSTC, s. 3.9.8).

Loads and wind

Duty class: Live load per platform: light 1.2 kPa, intermediate 2.4 kPa, heavy 3.6 kPa (CSA S269.2-16, clause 6.2.3). A province may set a higher minimum, such as Ontario at 2.4 kPa. Scaffold never picks it for you.
Load takedown: Load each standard transmits to its support (dead load and live load, unfactored) and pressure under the sole plate.
q1/50: Hourly wind pressure with a 1-in-50 annual probability of being exceeded, at the site (NBC 2020, Appendix C, Table C-2). Fencing and Scaffold use it for the wind check.
Overturning: A panel or scaffold tipping over under wind. The plan compares the overturning moment with the resisting moment of the bases and ballast.
Moment ratio: Resisting moment divided by overturning moment. Below 1.00, the fence overturns; at 1.00, it just holds, with no margin.

The site fence

Hoarding: Site fence that closes the site, often along a scaffold on the street side, and protects passers-by.
Fence panel: Prefabricated fence unit, mesh in the examples, set on bases. No panel is cut: when a run does not come out even, the last panel overlaps the one before.
Fence base: Concrete block that holds the panel posts. At a joint, a single base takes the posts of both adjacent panels.
Stay: Diagonal member, with its base, that holds the fence on the site side, at each corner and each end of a fixed fence. A ballasted stay also helps the fence hold against wind.
Ballast: Weight placed on the bases so the fence does not overturn in the wind. The plan calculates the weight to place on each base.
Clearance: Distance between the scaffold and the hoarding, on the street side and at both ends. Fencing needs it to place the fence.
Scaffold footprint: Ground area taken by the scaffold, plus a geometric clearance of 0.60 m by default. No part of the hoarding may enter it. This clearance is a design assumption, not a regulatory minimum.
Public walkway: Protected passage for pedestrians, between the hoarding and the street.
Lot line: Boundary of the site's land, on the street side or on the sides. Without it, the plan does not check whether the hoarding or the public walkway goes past it.
Party wall: Wall shared with the neighbouring building, at the end of a façade. The scaffold stops at that end, without the sole plate crossing the limit.
Total footprint: Total length the scaffold takes on the ground, sole plates included. The plan gives it with the clear space to each limit.

The plan and its documents

Preliminary: First status of a plan, before FOR APPROVAL and APPROVED FOR ERECTION. Only the last one allows erection. Each revision sets the plan back to PRELIMINARY.
Drawing number: Number that identifies the plan, the same on every sheet (ECH-… for Scaffold, CLO-… for Fencing). Quote it with its revision.
Revision: Letter of the plan's version (A, B, C…). The revision table gives its date, purpose and author.
Title block: Box at the bottom right of each sheet: company, title, site, authors, scale, drawing number, revision and status.
Bill of materials: List of the plan's parts: item, quantity, description, part number, dimensions and weights. Weights are indicative.
Not in catalogue: Note in the bill of materials for a part missing from the company's library. The plan keeps the generic part.
Not checked: Check the plan does not perform because a value is missing. The line names it, and the revision that receives it adds the check.
TK reference and check code: "Ref. TK-…" identifies the delivery: the plan, its revision and all its files. The check code comes from a signature only TektonAI can produce. The QR code opens the public verification page.
IFC model: 3D model of a building, in the open IFC format, supplied by the architect. Scaffold reads its storeys, walls, doors and windows.
CAD plan (DXF): Plan in DXF format, to open in drawing software. It arrives a few minutes after the other files.
3D model (STEP): 3D model of the scaffold in STEP format, to open in drawing or modelling software.

Rules and standards

NBC 2020: National Building Code of Canada, 2020 edition. On the plans, the article cited follows the acronym.
CSTC: Quebec Safety Code for the construction industry (CQLR, c. S-2.1, r. 4), cited by section. Subdivision 3.9 covers scaffolds.
CNESST: Quebec's labour standards, pay equity and workplace health and safety board.
CSA S269.2-16: CSA design standard for access scaffolding, 2016 edition, cited by clause. It sets the duty classes (clause 6.2.3).
CSA Z797:23: CSA standard for the erection, use and inspection of access scaffolding, 2023 edition.
Competent person: Qualified person who checks the plan before erection or installation. An engineer must sign it when the province's regulations require it.