---
title: "Check 7: Drainage Mat Orientation and Edge Overlaps"
url: https://stacklist.com/card/4a0c5725-49af-4b33-8735-14fd0660f8b9
stack: https://stacklist.com/c/business/stack/8b50c285-c1e7-42de-ac4c-343659a54e54
summary: "Check 7 is an inspection checklist for drainage mat orientation and edge overlaps on roofing membranes, requiring dimpled-side-down installation with minimum 2-inch seam overlaps and proper termination at drains and scuppers. All items must be signed off by an inspector before protection board installation can proceed."
tags: "drainage-mat, roofing-inspection, quality-control, membrane-protection, construction-checklist, edge-overlaps, hold-point"
key_entities: "drainage mat (concept), DM2 drainage mat (concept), membrane (concept), protection board (concept), scupper (concept), hold point (concept)"
classification: "checklist"
content_hash: "sha256:e48b23289c0c3200e6b5a18f3df6d57c04676e63c07d63e9fce3c2e1f75132d8"
acp_version: "0.2"
token_counts_approximate: 472
visibility: public
agent_accessible: true
status: "final"
---

# Check 7: Drainage Mat Orientation and Edge Overlaps

Check 7: Drainage Mat Orientation and Edge
Overlaps 
Hold Point: Drainage mat must be inspected before protection board and topping are placed. 
Orientation 
[ ] DM2 drainage mat is installed dimpled side DOWN against the cured membrane 
[ ] Filter fabric side is facing UP toward the topping or protection board 
[ ] No sections installed upside down: confirm by visual inspection before any area is covered 
Layout and Coverage 
[ ] Drainage mat covers the full membrane area: no gaps or uncovered zones 
[ ] Rolls or panels are butted tightly: no gaps wider than 1/4 in. between sections 
[ ] Mat is cut cleanly at all edges: walls, curbs, drain rings, scupper flanges 
[ ] No sections of drainage mat are folded, kinked, or buckled 
Edge Overlaps at Seams 
[ ] All seam overlaps are a minimum of 2 in. 
[ ] Overlaps are consistent: upper sheet over lower sheet in the direction of drainage 
[ ] No exposed membrane visible through open seams or gaps 
Termination at Drains and Scuppers 
[ ] Drainage mat terminates at the drain ring edge: not covering the clamping ring 
[ ] Drain clamping ring is accessible and confirmed torqued before mat is placed 
[ ] Drainage mat terminates at the scupper throat: no material blocking the opening 
[ ] Mat is cut cleanly at all penetrations: no bunching or overlap at pipes or posts 
Inspector Sign-Off 
8/8/26, 12:58 AM Check 7: Drainage Mat Orientation and Edge Overlaps 
https://md2pdf.netlify.app 1/2 

Item Pass Inspector Date 
Dimpled side down, full coverage [ ] __________ __________ 
All seam overlaps 2 in. min [ ] __________ __________ 
Drain and scupper termination clear [ ] __________ __________ 
No gaps or exposed membrane [ ] __________ __________ 
Do not place protection board until all drainage mat checks are signed off. 
8/8/26, 12:58 AM Check 7: Drainage Mat Orientation and Edge Overlaps 
https://md2pdf.netlify.app 2/2