Estimating man-hours with a Schedule of Norms

Introduction

Avontus AI Scaffold Connect can turn a scaffold model into the quantities your estimate is built on, then apply your labor units and productivity factors to them.

Ask in plain language, and the arithmetic, the assumptions and the source of every figure comes back with the answer. This page explains the terminology, what the connector supplies, and the one thing it will not do.

The Calculation

US industrial and EPC estimating converts a measured quantity of scaffold work into the man-hours needed to erect, modify and dismantle it:

Quantity × Labor Unit × Productivity Factors = Estimated Man-Hours

The concept is simple. The difficulty is choosing the right quantity, the right labor unit and the right factors for the work in front of you.

The connector supplies the quantity. You supply everything else. That split is deliberate, and the rest of this page is mostly about why.

Terminology

Quantity - The measured amount of work a labor unit applies to: pieces, weight, volume, face area, linear feet, leg feet, decks, stair towers.

Unit of Measure (UOM) - How that quantity is measured. EA, lb, ton, ft², ft³, LF, leg-ft. A UOM on its own says nothing about productivity; it only defines the measurement basis.

Labor Unit - The man-hours required for one unit of work. 0.10 MH/EA  means each component is estimated at 0.10 man-hours, or six minutes. A labour unit should state its scope: an erection unit does not silently include dismantling, modification, material handling or supervision.

Unit Man-Hours (UMH) - The same thing in tabular form. 0.10 UHM/EA is 0.10 man-hours per piece.

Productivity Rate - The same relationship inverted: work completed per man-hour. A labor unit of 0.10 MH/EA is a productivity rate of 10 EA/MH. Avontus works in labor units, because they multiply directly by a quantity.

Base Man-Hours - Quantity x Labor Unit, before any adjustment 831 AW x 0.10 MH/EA - 83.1 MH.

Productivity Factor - An adjustment for conditions that make the work more or less productive than the base norm assumed: elevation, congestion, restricted access, material handling distance, operating-unit restrictions, confined areas, complexity, suspended scaffold, weather, PPE, shift conditions, sequencing, repeated modifications, shutdown or turnaround. A factor of 1.25 is 25% more man-hours than base.

Estimated Man-Hours - The total predicted for the defined scope, after adjustment.

Actual Man-Hours - Actual Man-hours the completed work really took. Comparing actual against estimated is how an organization calibrates its own norms over time.

Schedule of Norms - Your organization's or project's structured set of labor units, together with the rules and factors that turn quantities into man-hours.

Man-hours are not duration

One person for eight hours is eight man-hours. A six-person crew for eight hours is 48. Converting to a schedule means dividing by crew size, and even then it ignores breaks, overtime, shift constraints and sequencing:

96 MH ÷ 6 scaffold erectors = 16 crew-hours.

Roughly two eight-hour shifts for that crew, all else being equal.

What the connector supplies

Every quantity basis in common use maps onto something the connector already reads from your model:

As the bill of materials is itemized, a Schedule of Norms does not have to apply one labor unit to a whole scaffold. Different material categories can carry different units, which is usually more accurate, since a standard, a ledger, a deck and a small clamp do not take equal effort to handle.

A note on model metrics

Volume, area and leg length are calculated figures, and they are only available for models exported from Avontus Designer 6.10.1396 or later. On an older model the connector says so and returns nothing, rather than estimating.

It will not reconstruct those figures from the bill of materials either. That restraint is the point: a derived surface area looks authoritative, and a bid gets built on it. Piece-based and weight-based estimating stay exact on every model, including older ones, so those bases remain available when the metrics are not.

Using it

Ask in plain language. Supply your own labor unit and the connector does the rest.

You: My erection norm is 0.10 MH per piece. How many man-hours is my Piperack scaffold?

Assistant: Piperack Scaffold has 1,004 pieces. 1,004 EA × 0.10 MH/EA = 100.4 base man-hours. That is erection only, using the 0.10 MH/EA figure you supplied, before any productivity factor. Dismantling would need its own labor unit.

Add conditions and it will ask how they combine rather than assuming:

You: It's in a congested process area, factor 1.25, and add 1.10 for elevation.

Assistant: Are those meant to be multiplicative? Applied that way: 100.4 × 1.25 × 1.10 = 138.1 man-hours. Some estimating bases treat factors as additive, mutually exclusive, or conditional instead, and the result differs, so tell me which your procedure uses and I'll follow it.

Other things worth asking:

• Break the bill of materials into material categories so I can apply a different labor unit to each.

• What's the total leg length on this model? I estimate by leg feet.

• We recorded 120 actual man-hours on 1,000 pieces. What was our real labor unit, and how does it compare to the 0.10 we estimated?

• Group this model by elevation so I can apply an elevation factor per lift.

What the connector will not do

It will not tell you how many man-hours a scaffold should take. There is no single US standard that establishes that figure. Scaffold safety and engineering are governed by regulation, code and engineering practice; labor productivity is not. Industrial contractors, EPCs and owners each maintain their own norms, drawn from their own historical performance, their estimating practices and their commercial agreements.

So the connector will not volunteer a labor unit or a productivity factor, and it will never describe one as an Avontus recommendation or an industry standard.

If you ask it for a starting point, it will give one, clearly labeled as an illustration for showing the calculation, and it will tell you to replace it with your own documented figure.

It will not blur separate activities. Erection, modification and dismantling get their own labor units. Modifications in particular often differs sharply from new erections, because crews work around an existing structure, other trades and operating equipment.

It will not guess how your factors combine. Multiplicative, additive, mutually exclusive, conditional, or already built into a specialized labor unit: it asks, and it preserves your method.

Recording a norm

A labor unit is more useful with its assumptions attached. A traceable norm records something like:

Common sources are company historical actuals, a corporate estimating database, owner or EPC estimating requirements, project procedures, contractual schedules, estimator and superintendent experience, and published references. Historical actuals are the most valuable when the recorded scope and conditions genuinely resemble the work being estimated.

Where the line sits

The model describes the work. The Schedule of Norms describes the estimating assumptions. The estimate predicts the man-hours those assumptions imply.

Scaffold Model → Quantities → Labor Units → Productivity Factors → Estimated Man-Hours. Keeping those separate is what makes an estimate explainable and auditable afterwards, and it is why the connector supplies the left-hand side and leaves the rest to you.

A Schedule of Norms is an estimating basis, not a safety standard. OSHA requirements, engineering requirements, manufacturer instructions and owner specifications determine how a scaffold must be designed, erected, used, inspected and dismantled. A Schedule of Norms only estimates the labor associated with that work.

Any numerical labor unit or productivity factor shown on this page is an example for explaining the calculation. These are not published Avontus labor norms and are not generally accepted industry productivity standards.