Underlayments, membranes and WRBs
What roof underlayment, ice barrier membranes and wall water-resistive barriers do and how each laps with the metal, the code rows and product limits that govern them, how they are installed with worked extent and lap checks, and the faults an inspection looks for.
4 lessons · about 51 min · 8 diagrams · 5 videos
Version 1.0.0
Builds on these modules
Lessons
0 of 4 complete
Lesson 1 · 12 min · 10 slides · 10 questions
Underlayments, membranes and WRBs: principles and terminology
What each layer does, the code terms and their trade names, the shingle-fashion rule, where each layer meets the drip edge and step flashing, and the OSHA roof definitions.
You will be able to: Define underlayment, ice barrier, self-adhering membrane, water-resistive barrier, shingle fashion and head and end laps, place each layer against the metal, and state the fall-protection boundaries.
Not startedStart →Lesson 2 · 14 min · 12 slides · 12 questions
Underlayments, membranes and WRBs: materials, standards and design constraints
Felt and its ASTM types, synthetics and evaluation reports, self-adhering membranes and their heat ratings, compatibility and exposure limits, the code rows by slope and wind, the ice barrier rule, and the wall WRB.
You will be able to: Identify felt, synthetic and self-adhering underlayments by their standards, read product heat, compatibility and exposure limits, and apply the code rows for slope, wind design, ice barrier and wall WRB.
Not startedStart →Lesson 3 · 13 min · 12 slides · 9 questions
Underlayments, membranes and WRBs: methods and worked application
How the layers are installed: a dry-in sequence from eave to wall, the eave order in the code and in makers' instructions, three worked calculations, the roof-wall lap order and the wall WRB laps.
You will be able to: Follow a documented dry-in order, resolve the eave order against the product instructions, calculate ice barrier extent and two-layer coverage with units, and install the laps at roof-wall corners and walls.
Not startedStart →Lesson 4 · 12 min · 12 slides · 9 questions
Underlayments, membranes and WRBs: defects, verification and case study
The common faults and the source each one misses, an inspection checklist, what to record, a fall from a rain-slick deck, and a roof-wall leak traced to its laps.
You will be able to: Diagnose reverse laps, missing turn-ups, short ice barriers and wrong or overexposed products, check a dry-in against its documents, and record corrective options with evidence.
Not startedStart →
Practical task
Prepare a job packet for drying in one eave and one roof-to-wall corner of a sloped roof: decide and justify the underlayment, any ice barrier and the WRB laps against the adopted documents, work the extent and lap arithmetic, mark up the installation sequence, check it, and analyse one defect.
Hand in
- A decision rationale: the code edition and jurisdiction, slope and wind-design status, ice barrier requirement, and each product with its standard, evaluation report or data sheet
- A marked-up sketch of the eave and the roof-wall corner: drip edge, ice barrier, field underlayment, turn-up, kick-out, step flashing, WRB and siding clearance, with laps in inches and the eave order stated
- Measurement assumptions and arithmetic: ice barrier extent along the slope with the slope factor, and courses or sheet laps, each input labelled as a code, product or example value
- A completed inspection checklist: laps, end-lap offsets, ice barrier extent, turn-up, product rating for the roof and metal, exposure time and compatibility
- A defect analysis for one fault found or seeded: what it was, the document and value it misses, the corrective option chosen and the photo evidence
Rubric
| Criterion | Meets the standard when |
|---|---|
| Documents | Every value names its owner and edition: the adopted code text, an evaluation report, or a maker's data sheet. No AFS value is claimed for any layer. |
| Lap order | Every lap sheds water upper over lower; the eave order follows the adopted code, or a conflict with the product instructions is raised and recorded. |
| Arithmetic | Extent and coverage are worked in inches with the slope factor and laps shown, and example inputs are labelled as examples. |
| Roof-wall corner | Underlayment turned up at least 6 in, kick-out as the first piece, step flashing at least 4 in each way, WRB over the flashing, siding 1 in clear. |
| Products | Heat rating, metal approval, compatibility and exposure limits are read from the product's own document. |
| Safety | The packet states the OSHA roof category and the 1926.501 paragraph that applies, and plans to cover the deck promptly. |