Construction scheduling and trade interfaces · Lesson 1 of 4

Construction scheduling and trade interfaces: principles and terminology

Critical path, float, hand-offs, procurement as work, weather as a calendar and the fall-protection and site-control rules, all seen from where flashing meets another trade.

You will be able to: Define the schedule terms a flashing crew meets, explain interfaces and hand-offs between trades, and state the safety boundaries for heights and shared sites.

13 min · 12 slides · 10 questions

All lessons in this module

Slide 1 of 12

Flashing is where trades meet

Building Science Corporation says a flashing can protect an interface between two different enclosure elements.

Flashings are needed wherever a drainage plane ends or is interrupted, such as at a roof edge, an opening or a penetration.

Here, an interface is where one trade’s work meets another’s, and a hand-off is when responsibility for a layer passes on (this module’s own terms).

A: Roof membrane (installer set by the contract)
B: Base flashing turned up the wall (installer set by the contract)
C: Through-wall flashing with its drip (installer set by the contract)
D: Weep tube (installer set by the contract)
E: Drainage plane, dashed, lapped down over the through-wall flashing (installer set by the contract)
F: Receiver of a two-piece counterflashing, AFS-type metal in red (installer set by the contract)
G: Counterflashing hanging from the receiver over the base flashing, AFS-type metal in red (installer set by the contract)

Schematic, not to scale. Every layer has one owner, and the contract names it; the laps are where two owners meet. Red marks sheet metal of the kind AFS fabricates. The receiver and counterflashing follow the arrangement in the Roofing Magazine photographs; the other layers are general.

Sources

Common Flashing Details for All Climates, BSC Information Sheet 303 - Building Science Corporation, for the U.S. Department of Energy Building America program

Glossary

Critical path: The longest continuous sequence of activities in a schedule. It sets the earliest completion date, and a delay on it moves the finish by the same amount.
Total float: The amount of time an activity can slip before the project end date is affected. Critical activities have zero total float when the schedule has no date constraints.
Near-critical activity: An activity with little total float, which can quickly become critical if its float is used up by a delay.
Free float: The amount of time an activity can be delayed without affecting any of the activities that follow it.
Constraint: In the Last Planner method, a directive, resource or prerequisite piece of work, not already shown on the plan, that a task needs before it can start and finish.
Interface: In this module, the place where one trade’s work meets another’s, such as roof base flashing meeting a wall. Building Science Corporation describes a flashing as able to protect an interface between two different enclosure elements.
Hand-off: In this module, the moment responsibility for a layer of the building passes from one crew or trade to the next.
Submittal: Information sent to a reviewer to show that the work will comply with the contract documents, such as shop drawings, product data and samples.