Product selection and substitutions
How a specification selects a product, what equal has to cover on a flashing assembly, a documented comparison method with worked examples, and how a bad substitution shows up and is checked on receipt.
4 lessons · about 47 min · 13 diagrams · 0 videos
Version 1.0.0
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Lessons
0 of 4 complete
Lesson 1 · 12 min · 12 slides · 9 questions
Product selection and substitutions: principles and terminology
Why a small product change is rarely small, where the substitution rules live in a project manual, how a specification selects a product, the difference between a comparable product and a substitution, and who decides.
You will be able to: Define selection procedure, basis-of-design product, comparable product, substitution and code alternative, say which procedure a given specification wording triggers, and name who decides.
Not startedStart →Lesson 2 · 13 min · 12 slides · 10 questions
Product selection and substitutions: materials, standards and design constraints
What equality has to cover on a flashing assembly: how gauge, weight and decimal-inch thickness differ by metal, how much each metal moves, which metals should not share runoff, and why a wind rating belongs to a whole tested assembly.
You will be able to: Compare two candidate products on thickness, thermal movement, galvanic behavior, finish evidence and tested-assembly status, and state which constraints a substitution can break.
Not startedStart →Lesson 3 · 12 min · 11 slides · 9 questions
Product selection and substitutions: methods and worked application
A step-by-step method for comparing a proposed product with a specified one, four worked examples with every input sourced, the review clock in one owner’s template and what a request packet holds.
You will be able to: Produce a documented substitution comparison with sourced inputs, units, assumptions and inspection points, and read the review clock and request packet.
Not startedStart →Lesson 4 · 10 min · 10 slides · 8 questions
Product selection and substitutions: defects, verification and case study
How a bad substitution shows up, the arithmetic of a lighter gauge, why copying a tested profile does not copy its test, receiving checks, a constructed galvanic case study and how to document it for review.
You will be able to: Diagnose a plausible substitution defect, explain corrective options, and document the evidence a reviewer needs, including when the honest answer is no.
Not startedStart →
Practical task
Produce a documented substitution job packet for a specified 24 ga galvanized steel coping cover and a proposed .040 in aluminum cover: compare them row by row with units and sources, mark each row, and record what evidence is still missing before any decision is asked for.
Hand in
- A one-page decision rationale that says what the specification names, which selection procedure it triggers and who decides.
- A marked-up sketch or detail of the coping assembly with the seven lettered checks (metal and thickness, movement, contact with other metals, finish and color, cleat and fasteners, wind-tested assembly, warranty) each pointing to the part it concerns.
- A comparison table with one row per attribute, each value with its unit and source: thickness (0.0276 in against 0.040 in), movement over a 120 in piece and 100 degF (0.078 in against 0.1536 in), and the published rating of each cover on the system named.
- Assumptions listed in plain words, with every example value marked as an example and every manufacturer value marked as the manufacturer’s.
- A receiving checklist for the eight checks and a short defect analysis for one failure, such as copper runoff onto an aluminum downspout, with the options you would put to the designer.
Rubric
| Criterion | Meets the standard when |
|---|---|
| Procedure and decision-maker | The wording is read correctly (single product, restricted list or basis of design), the right process is named, and the design professional is shown as the decider. |
| Sourced comparison | Every row has a value with a unit and a source, the thickness ratio 1.449 and the movement ratio 1.97 are worked correctly, and manufacturer values are labelled as theirs. |
| Statuses and missing evidence | Each row carries Match, Differs, Not offered or Evidence missing, and evidence that is missing is listed rather than assumed. |
| Tested assembly | The packet says a changed cover or cleat is a different assembly, and quotes the published rating for the system it names without extending it to another system. |
| No approvals, no prices | Nothing says a product is approved, equal or meets code, no price appears, and fall-protection rules are mentioned for roof-edge work. |