New-Construction Substrate Readiness and Trade Coordination

Substrate Acceptance Is a Formal Handoff

Substrate acceptance should be a defined project hold point—not a quick visual check performed while the coating crew is mobilizing. The contract documents should identify who provides the substrate, who protects it, who tests it, who corrects defects, and who authorizes coating application.

Acceptance by the roof-coating contractor confirms only the observable and testable conditions within that contractor's scope. It does not transfer the architect's, engineer's, manufacturer's, general contractor's, or substrate installer's design obligations to the coating contractor.

The Preinstallation Coordination Meeting

Before mobilization, conduct a meeting with the owner, design professional, general contractor, roof-system manufacturer, substrate installer, and affected trades. Record decisions in meeting minutes and distribute them before work begins.

• Confirm the approved roof assembly, product data, details, listings, warranty requirements, and current manufacturer instructions.
• Identify substrate types, transitions, slopes, drains, penetrations, curbs, joints, terminations, and areas requiring reinforcement.
• Define moisture-testing methods, locations, frequency, acceptance criteria, and the party responsible for testing.
• Confirm surface-profile, cleanliness, primer, adhesion-test, and pull-test requirements.
• Establish weather limits, daily start and stop procedures, temporary dry-in measures, and overnight protection.
• Coordinate air-intake shutdowns, occupied-building protection, overspray control, access, staging, material storage, and emergency procedures.
• Establish inspection hold points and written authorization to proceed.

Readiness by Substrate

Structural Concrete

Concrete must be sound, adequately cured, sufficiently dry for the specified system, and free of laitance, curing compounds, form-release agents, sealers, oil, dust, and other bond breakers. Cracks, voids, honeycombing, fins, sharp projections, construction joints, and penetrations must be treated as required by the approved design.

A stated curing age—such as 28 days—does not prove that a roof deck is dry. Concrete can retain significant moisture long after strength development. ASTM D4263, the plastic-sheet method, indicates moisture present at the surface under the sheet; it should not be represented as proof that the deck is dry throughout.

When in-situ relative-humidity testing such as ASTM F2170 is specified, remember that it was developed for concrete floor slabs. Its use and acceptance limits for a roof deck must come from the project specification, design professional, or roof-system manufacturer—not from an assumed universal threshold.

Where a prepared concrete surface profile is required, use the coating manufacturer's specified preparation method and acceptance standard. ICRI Guideline No. 310.2R describes Concrete Surface Profile comparators CSP 1 through CSP 10, but the correct profile is system-specific; one CSP value should not be imposed on every liquid-applied roof membrane.

Gypsum, Cementitious, and Insulation Cover Boards

Verify the approved board type, thickness, orientation, attachment pattern, fastener seating, joint layout, edge support, and compatibility with the liquid-applied system. Reject or replace wet boards, crushed edges, broken corners, delaminated or torn facers, bowed panels, unsupported joints, open gaps beyond the system allowance, and boards contaminated by mud, oil, or construction debris.

Do not attempt to hide damaged or wet cover boards beneath primer, mastic, fabric, or additional coating. The substrate must provide the stable, continuous surface required by the tested and warranted assembly.

Metal Roof Decks and Panels

Confirm that the metal type, factory finish, corrosion condition, fasteners, seams, laps, welds, and transitions match the approved system. New metal can carry rolling oil, shop soil, temporary protective film, passivation treatments, or factory finishes that interfere with adhesion. Remove welding slag, filings, sharp edges, loose rust, oil, and incompatible materials using the approved preparation procedure.

Coordinate loose or missing fasteners, panel movement, seam design, dissimilar-metal contact, and corrosion correction before coating. A field adhesion test does not eliminate the need to identify the substrate and verify compatibility.

Wood Structural Panels

Where the listed system permits plywood or other wood structural panels, verify the specified panel grade, thickness, span, orientation, fastening, joint spacing, edge support, moisture condition, and fire or code requirements. Replace swollen, delaminated, decayed, wet, or structurally damaged panels. Do not assume that a liquid-applied roof system is approved directly over every wood product.

New Single-Ply Membranes or Other Approved Surfaces

Some designs use a liquid-applied coating or reinforced membrane over a new manufactured membrane or accessory. Confirm that this construction is expressly approved. Address release films, processing lubricants, seam treatments, surface oxidation, dust, footprints, and incompatible sealants. Follow the manufacturer-specific cleaning, priming, abrasion, and test-patch requirements.

Complete the Details Before the Field Membrane

Penetrations and terminations frequently determine whether an otherwise sound roof succeeds. Before broad-area application, verify that the following work is complete, secure, and ready for the specified liquid-applied details:

• Roof drains, scuppers, overflows, gutters, and conductor heads
• Equipment curbs, pipe supports, sleepers, and equipment rails
• Pipes, conduits, ducts, pitch pans, and electrical penetrations
• Expansion joints, control joints, area dividers, and changes in plane
• Perimeter edges, parapets, copings, counterflashings, and wall transitions
• Lightning-protection components, solar supports, guardrails, and fall-protection anchors

Late penetrations and post-application modifications should require written coordination, approved detailing, and reinspection. Cutting through a completed membrane and applying generic sealant is not an acceptable closeout procedure.

Trade Responsibilities and Coordination

Protecting Completed Work

The coating plan should account for work that continues after membrane installation. Establish controlled walkways, access routes, barricades, and protection approved by the roof-system manufacturer. Prevent damage from foot traffic, carts, cranes, stored equipment, dropped fasteners, welding, grinding, hot work, solvents, hydraulic fluid, refrigerant oil, sealants, and construction debris.

Roof materials should be stored within temperature limits, kept dry, secured against wind, and distributed within structural loading limits. Wet or contaminated material should be quarantined and evaluated before use.

Substrate-Readiness Hold-Point Checklist

1. Approved drawings, specifications, submittals, details, listings, and manufacturer instructions are available at the site.
2. The installed substrate and complete roof assembly match the approved design.
3. Drainage, slope, elevations, curbs, penetrations, edges, and transitions have been verified.
4. Moisture-testing method, locations, results, limits, and authorization are documented.
5. Wet, damaged, unstable, contaminated, or nonconforming materials have been removed or corrected.
6. Required cleaning and surface preparation have produced the specified condition and profile.
7. Adhesion test patches, pull tests, primer trials, or mockups have passed the stated acceptance criteria.
8. Environmental conditions and the forecast comply with product requirements.
9. Other trades have completed prerequisite work and a protection plan is active.
10. Open issues have been resolved in writing, and the designated party has released the area for application.

Technical References

• IIBEC Technical Advisory No. 013-2017—Removal and replacement of roof substrate materials damaged by entrapped moisture or moisture intrusion during new roof installation.
• ASTM D4263-24—Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method.
• ASTM F2170—Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes. Use for roof-deck evaluation only when required and interpreted by the project documents or system authority.
• ICRI Guideline No. 310.2R-2013—Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, Polymer Overlays, and Concrete Repair.
• NRCA Guidelines for Roof Coatings—Current industry guidance for roof-coating evaluation, design, preparation, application, and quality control.

Application rule: The current project specification, approved manufacturer details, product technical data sheets, safety data sheets, listings, and written warranty requirements control the work. Manufacturer examples and industry references are educational resources, not product endorsements.