Architectural Flashing Supply
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Substrates, blocking and attachment · Lesson 4 of 4

Substrates, blocking and attachment: defects, verification and case study

A twelve-point substrate check, correct and incorrect details, the attachment defects that recur and their fixes, two views on exposed fasteners, a powder-actuated tool boundary, and a worked case of a lifted corner.

You will be able to: Inspect a substrate and its fastening before the metal goes on, diagnose a plausible attachment defect, name the rule it breaks with its source, choose a corrective option and document the evidence for review.

11 min · 12 slides · 8 questions

All lessons in this module
Slide 1 of 12

Inspect the substrate first

Check before the cover goes on, against the drawings and the guide:

  • Wood sound, no rot or splits
  • Thickness, height and width
  • Fasteners per member, end distance, spacing
  • Anchorage to the engineer's design
  • Fastener metal, isolation, cleat height
  • The printed pattern, corners closer
Twelve substrate checks before the cover goes onA checklist card of twelve numbered rows, each with a short label and a tick box: wood sound, 1.5 in per layer, flush with insulation, flange plus 1/2 in, 2 per member and end distance, 12 in and 6 in at corners, anchorage to the design, fastener metal, metal isolated from treated wood or compatible with it, cleat at detail height, printed pattern, face 1 in over the wall. Below it, the fields of an evidence log.Substrate checkswood sound1.5 in per layerflush with insulationflange + 1/2 in2 per member, ends12 in, 6 in at cornersanchorage to designfastener metalisolated or compatiblecleat at detail heightprinted patternface 1 in over walllocation, photo, measured,required, source, pass, initialsEvidence log123456789101112

A checklist card of twelve numbered rows with a short label each: sound wood, thickness, flush height, width, fasteners per member, stacked spacing, anchorage, fastener metal, isolation, cleat height, printed pattern, coverage over the wall. Below it, the fields of an evidence log.

1
Wood sound: no rot, no splits (proposed ED-1)
2
Each layer at least 1.5 in thick (proposed ED-1)
3
Top flush with the insulation (Carlisle: flush with the membrane underlayment; built to the detail)
4
Width at least flange + 1/2 in (proposed ED-1)
5
Each member: at least 2 fasteners, about 4 in and not less than 3 in from the ends (proposed ED-1 commentary)
6
Stacked members: at most 12 in on center, 6 in in corners (proposed ED-1 commentary)
7
Anchorage to the engineer's design; drawing reference recorded
8
Fastener metal suits the wood treatment (the adopted code, NRCA)
9
Metal isolated from treated wood, or galvanically compatible with it (proposed ED-1); Drexel's note 1 requires a membrane
10
Cleat at the detail height (2024 Wall of Wind tests)
11
The maker's printed fastener and spacing, closer at corners
12
Coverage at least 1 in over the wall face (proposed ED-1)
Values from SPRI's October 2025 proposed ED-1 revision and the Drexel guides; the project spec, approved drawings and the engineer govern.

Sources

Glossary

Spalled area
Broken-out material left around an unsatisfactory powder-actuated fastening; 29 CFR 1926.302(e)(9) bars driving another fastener into it.
Corner region
The edge zone at a building corner, where commentary in the October 2025 proposed ED-1 revision closes stacked-nailer fastener spacing and edge makers such as Drexel print closer cleat fastening.
Exposed fastener
A fastener left visible through the outer face of edge metal; FEMA P-2181 lists them for the vertical flanges of copings and edge flashings.