---
title: "Step 1: Substrate Assessment and Pre-Installation Conditions"
url: https://stacklist.com/card/b42ce1f1-e102-4895-9193-ff9e65b867fa
stack: https://stacklist.com/c/business/stack/2d67154e-83fe-4367-99db-e7e4088ce2f9
summary: "Step 1 outlines substrate assessment and pre-installation conditions for FM ELEVATION system products, requiring minimum acceptance criteria for concrete and wood-framed decks to prevent membrane delamination and warranty voids. The process includes verification of cure time, moisture levels, surface profile, slope, drain setup, and completion of a pre-installation sign-off checklist."
tags: "substrate-assessment, pre-installation, membrane-installation, concrete-decks, plywood-substrate, drainage, quality-control"
key_entities: "FM ELEVATION system (technology), membrane delamination (concept), substrate assessment (concept), positive drainage (concept), moisture content (concept)"
classification: "checklist"
content_hash: "sha256:1bf213eecffa479951ba55a8287e5990a2bdf374ec6b72219fe3c3f212f24921"
acp_version: "0.2"
token_counts_approximate: 519
visibility: public
agent_accessible: true
status: "final"
---

# Step 1: Substrate Assessment and Pre-Installation Conditions

Step 1: Substrate Assessment and Pre-Installation
Conditions 
Overview 
Before any FM ELEVATION system product touches the deck, the substrate must meet minimum
acceptance criteria. Skipping this step is the single most common cause of membrane delamination and
warranty voids. 
Concrete Decks 
Cure time: Minimum 28 days from pour before primer application 
Moisture: Maximum 75% relative humidity at slab surface (use a moisture meter or plastic sheet
test) 
Surface profile: Light broom finish or equivalent. No laitance, grease, form oil, curing compounds, or
standing water 
Cracks: Surface cracks wider than 1/16 in. must be routed and filled with compatible sealant before
priming 
Slope: Verify positive drainage. Minimum 1/8 in. per foot toward drain or scupper. Flat or back-
pitched decks require correction before proceeding 
Wood-Framed Decks (Plywood Substrate) 
Plywood grade: Minimum 3/4 in. tongue-and-groove Exposure 1 or better 
Fastening: Ring-shank nails or screws at 6 in. on center at panel edges, 12 in. in field. No loose or
squeaky sheets 
Gaps: Maximum 1/8 in. gap at panel joints. Gaps over 1/8 in. require backer rod and sealant 
Deflection: L/360 minimum. Bouncy or springy decks must be stiffened before membrane
installation 
Moisture: Wood moisture content must be below 19% (use a pin moisture meter) 
Drain and Scupper Rough-In 
Drains must be set to final elevation and secured before primer 
Scupper openings must be framed and flashed per project drawings 
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Confirm drain strainer and clamping ring are on site before work begins 
Pre-Installation Sign-Off 
[ ] Substrate type confirmed: concrete / plywood 
[ ] Cure or moisture requirements met 
[ ] Surface clean, dry, and profiled 
[ ] Slope verified 
[ ] All cracks treated 
[ ] Drains and scuppers set 
[ ] PM or GC sign-off: ______________ Date: ______________ 
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