Steel Mezzanine Estimator

Purpose and model boundary

This calculator takes off and estimates a steel mezzanine or elevated platform drawn on the page: columns on a grid, girders, beams and joists at one or more deck levels, column bracing, deck panels of grating, plate or composite metal deck with openings cut in them, stairs with their handrails, and guardrails. It counts the members drawn and gives each member's length, its section's idealized area and, when you enter a density, its weight; the deck area by deck type, less openings; each stair's flights, landings, rise, run and stringer length; and the guardrail and handrail lengths. Optionally it prices the steel by weight, the deck by area, the stairs each and the railings by length at rates you type.

It is an arithmetic takeoff of what is drawn, for estimating and learning. It is not a structural design, a fabrication bill of materials or a supplier quote.

The spreadsheet is the calculation authority. The page sends the drawn geometry, the sections table and the values you type to the workbook and shows only what the workbook returns.

Inputs and units

• The drawing. The column grid, the deck levels, the joist spacing, the deck panels and openings, the stairs and the guardrails are drawn on the canvas, in the Plan, Front, Side and 3D views. The canvas sends the model's nodes (x and y in plan, z up, in feet or metres), its members (start and end node, section, group and type), its member groups, each deck panel and opening with its corners in plan, and each stair, handrail and guardrail as a line of points.
• Deck type. Each deck panel is grating, plate or composite metal deck (steel deck with concrete fill), picked on the panel; a newly drawn panel takes the type set in the drawing's toolbar.
• Sections. Up to 12 rows in the calculator panel: a name, the profile (I, C, L, HSS, PIPE or RECT) and the dimensions that profile uses, in inches (US) or millimetres (Metric). Sections are assigned to members on the canvas.
• Density (optional) of the steel, in lb/ft³ or kg/m³. Left blank, the takeoff gives lengths and areas without weights.
• Stringers per stair flight, 1 to 4 (2 by default).
• Prices (optional): steel per pound or per kilogram; grating, plate and composite deck per square foot or per square metre; railings per foot or per metre; and a price for each stair. A blank price leaves its line unpriced; 0 is a real price.

Governing relationships

• Each member's length is the distance between its two end nodes.
• Each section's area is that of its idealized, sharp-corner outline, as the sum of its parts: I and C, 2·bf·tf + (d − 2·tf)·tw; L, t·(b + d − t); HSS, 2·t·(b + d − 2·t); pipe, π·t·(od − t); rectangle, b·d.
• Each member's weight is its length times its section's area times the density. The totals are in pounds and short tons of 2,000 lb, or kilograms and tonnes of 1,000 kg.
• Each deck panel's and opening's area is its plan area from its corners (the shoelace formula). An opening's area is taken off its deck panel: net deck area = deck areas − opening areas, by deck type.
• Along a stair's line, each segment that climbs is a flight and each level segment is a landing. The rise and run are the flights' height and horizontal length; the stringer length is the stringers per flight times the flights' sloped lengths.
• A railing's length is the sum of its segment lengths.
• Each priced line is its quantity times your unit price; the total adds up the lines that are priced.

Calculation sequence

1. The workbook checks the node, section, member, group, deck, corner and path rows and the prices, and refuses the first row that is wrong.
2. It works out each member's length from its two end nodes, and each section's area from its dimensions.
3. With a density, it works out each member's weight and each section's weight per length.
4. It adds the members up by type, by section and by group.
5. It works out each deck panel's and opening's area, and the gross, opening and net areas by deck type.
6. It splits each stair line into flights and landings and works out the rise, run and stringer length, and the guardrail and handrail lengths.
7. With prices, it prices the steel, the deck by type, the stairs and the railings, and adds up the priced lines.

Outputs and interpretation

• Steel takeoff: the member count, the total length of every member (end node to end node, with no allowance for cutting, laps or waste), and the total weight in pounds or kilograms and in short tons or tonnes.
• Deck: the net, gross and opening areas, and the numbers of deck panels and openings; by deck type and panel by panel.
• Stairs and railings: the stairs, flights and landings, the total rise and run, the stringer length, and the guardrail and handrail lengths; stair by stair and rail by rail.
• By type, by section and by group: the count, the total length and the total weight of the members of each; for a section, also its area, its second moments Ix and Iy and its weight per foot or metre.
• Estimate: each priced line and their sum, with whether everything, part or nothing is priced and how many lines have a quantity but no price.

Weights are blank until a density is entered.

Validation and status logic

The status reads OK when the drawing can be taken off. NOT VALID names the first row or input to fix, and every number is then blank, while the member, panel and path tables still show each row's status. CHECK flags a takeoff that is counted but worth a look, such as member types that differ only in letter case, which are counted together under the first spelling.

Assumptions and limitations

Only what is drawn is counted: no connections, base plates, bolts, welds, coatings, deck or grating weight, stair treads, toe plates, posts or kick plates, and no cutting or waste allowance. Deck panels are horizontal. Real rolled shapes have fillets and corner radii, so their published areas differ from the idealized outline's. The takeoff makes no strength, stability, deflection or vibration check and does not size anything. No price is a supplier bid or a current market rate.

Restrictions and non-computing states

• Up to 600 nodes, 600 members, 12 sections, 50 groups, 40 deck panels and openings with 240 corners, and 40 stairs and railings with 240 points; at most 20 member types.
• A deck panel or opening has at least three corners and an area above zero; a deck's openings add up to less than its area.
• A stair or railing has at least two points and no segment of zero length; a stair has at least one flight, and a flight has a horizontal run.
• A density must be above zero and at most 1,600 lb/ft³ (25,000 kg/m³). Prices are zero or more: steel at most $100 per lb ($220 per kg), deck at most $2,000 per ft² ($20,000 per m²), railings at most $5,000 per ft ($16,000 per m), a stair at most $5,000,000; a money result above $1,000,000,000 is refused.
• IDs must differ, compared without regard to letter case; an ID is at most 64 characters and holds none of * ? ~ < > =.

Errors and warnings

A drawing the workbook cannot take off reads NOT VALID with the first row to fix, for example a member whose section is not in the sections table, an opening whose host is not a deck panel, a path that mixes kinds, or two IDs that differ only in letter case. The canvas itself refuses a change that would not fit the workbook's tables, and says which table is full.

The method is an arithmetic takeoff of what is drawn. Each member's length is the distance between its end nodes, and each section's area is that of its idealized sharp-corner outline as the sum of its parts. Each deck panel's and opening's plan area comes from its corners by the shoelace (surveyor's) formula. Along each stair line, a climbing segment is a flight and a level segment a landing; the rise, run and stringer length are measured from the drawn points, and each railing's length is the sum of its segments. Weights are length times area times the density you enter. The workbook measures the stairs and railings but does not check them against any stair or guard rule. The full method is also stated on the workbook's References sheet.

Sources and further reading

• Centroids of composite areas, second moments of area and the parallel-axis theorem, used for each section's area and second moments: B. J. Goodno and J. M. Gere, Mechanics of Materials, 9th edition, Cengage Learning, 2018, appendix D, Review of Centroids and Moments of Inertia. Publisher page
• The area of a polygon from the coordinates of its vertices, used for the deck panels and openings: E. W. Weisstein, "Shoelace Formula", MathWorld, Wolfram Research. MathWorld
• Conversion factors for the pound, the short ton, the kilogram and the metric ton, and for lengths and areas between US and SI units: A. Thompson and B. N. Taylor, Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 edition, appendix B, Conversion Factors. NIST
• The published dimensions and properties of rolled steel shapes, which differ from the idealized outlines used here: American Institute of Steel Construction, Steel Construction Manual, 16th edition, 2023. AISC
• Further reading on the stair and railing rules for industrial platforms in the United States, which this calculator does not check: Occupational Safety and Health Administration, 29 CFR 1910.25, Stairways, and 29 CFR 1910.29, Fall protection systems and falling object protection, criteria and practices, paragraphs (b), guardrail systems, and (f), handrails and stair rail systems. 29 CFR 1910.25, 29 CFR 1910.29

No table, chart or text from a standard, manual or commercial publication is reproduced, and no section property comes from a shape table: every dimension and the density are entered by you or drawn on the canvas. None of the authors or publishers named here has reviewed or endorses this calculator.

The workbook was checked by two independent methods: a hand count from the mezzanine's dimensions, and an independent script over the exported nodes, members, deck corners and stair and railing points, including each section's area by its own split into parts.

Applicable building codes and a qualified engineer govern real structures, stairs and guards.