---
title: Membrane Roofing
…691 unchanged lines
- "12 in o.c. (standard commercial)"
- "18 in o.c."
− - "Per FM RoofNav listing — see drawings"
−default: "Per FM RoofNav listing — see drawings"
+default: deferred
```
…118 unchanged lines
type: radio
unit: in
+drawing_ref: "roof drawings"
options:
- "8 in (minimum)"
- "12 in (preferred; high-snow or high-debris environments)"
− - "Greater than 12 in — per drawings"
default: "8 in (minimum)"
```
…513 unchanged lines
### The plasticizer from the PVC migrates into the bituminous facer, stiffening the membrane, causing brittleness, and ultimately cracking. {note}
### Material compatibility confirmation between the membrane, adhesive, and cover board is a required submittal item and must be documented before installation begins.