Substrates, blocking and attachment · Lesson 1 of 4

Substrates, blocking and attachment: principles and terminology

Why edge metal is only as strong as what it is fastened to, the terms installers and engineers use, the attachment chain from cover to structure, the substrate cases, sealing, and the nail gun, powder-actuated tool, silica and fall rules.

You will be able to: Define substrate, nailer, blocking, load path, pull-out and pull-through, name the substrates edge metal is fastened over and who is responsible for each link, and state the attachment hazards and their rules.

14 min · 12 slides · 11 questions

All lessons in this module

Slide 1 of 12

Only as strong as its substrate

Commentary in SPRI's October 2025 proposed ED-1 revision says resistance to blow-off depends not only on how the edge is attached, but also on the integrity of the nailer or other substrate.

RICOWI and IBHS researchers, writing on Hurricane Ian, warn that when a nailer fails, every component above it fails too.

So metal, fasteners, wood and anchors are one system, checked link by link.

Sources

Videos for this lesson

What this video shows: MuleHide, a membrane maker, shows a metal edge set after the membrane runs down the nailer face, then flashed with its cover tape or strip: the layers on the nailer. MuleHide's products and rules, not a Drexel system.

Video: TPO: Drip Edge by MuleHide Videos, on YouTube. AFS checked its description against this lesson.

What this video shows: CPWR, a construction safety research center: veteran carpenters and research partners on what they learned about nail gun injuries.

Video: Nail Gun Facts by CPWR – The Center for Construction Research and Training, on YouTube. AFS checked its description against this lesson.

What this video shows: CPWR: carpenter apprenticeship instructors on the proper use of nail guns and compressors.

Video: Working with Nail Guns: The Facts (Part 1 of 3) by CPWR – The Center for Construction Research and Training, on YouTube. AFS checked its description against this lesson.

What this video shows: CPWR: the same instructors with more tips on safe nail gun use at the work site.

Video: Working with Nail Guns: The Facts (Part 2 of 3) by CPWR – The Center for Construction Research and Training, on YouTube. AFS checked its description against this lesson.

Glossary

Substrate: In ES-1, the upper surface of the roof deck, insulation or other roofing structure that a roofing component is placed on or attached to.
Nailer: In SPRI's October 2025 proposed ED-1 revision, a longitudinal member, typically wood, that a roof edge system is fastened to, directly or through clips, cleats, gutter brackets or gutter straps.
Wood blocking: Wood used to attach roof edge components; the October 2025 proposed ED-1 revision names wood blocking and nailers together and sets the same requirements for both.
Stacked nailer: An additional wood member added to a nailer; commentary in the October 2025 proposed ED-1 revision names stacked nailers with cant strips and has them fastened with corrosion-resistant fasteners.
Load path: The connection of roof members ultimately to the building foundation, which commentary in the October 2025 proposed ED-1 revision asks the design professional or authority having jurisdiction to judge complete.
Fastener pull-out: An ES-1 failure mode in which a fastener pulls away from its substrate, such as a nailer, under load.
Fastener pull-through: An ES-1 failure mode in which the fastener shank stays in the substrate and the roof edge component pulls over the fastener head.
Full sequential trigger: The nail gun trigger type that the NIOSH and OSHA nail gun guide calls always the safest trigger mechanism for the job.