MarkhamBuilding InspectionsInspections

Vapour Barriers for Medium Density (2lb Closed Cell) Spray-Applied Polyurethane Foam Insulation

Published by City of Markham

This is the City of Markham’s document, as published on its website on 18 October 2026. The municipality may have changed it since: check the current version at the source. Legal notice

Type: Guide
Published by: City of Markham
Date: January 1, 2025
Also called: Vapour Barrier for 2LBS Closed Cell Spray Applied Polyurethane Foam Insulation
For: builder
Building types: All building types
Pages: 3
Instruments: ASTM E96/E96M

Overview

Markham's three-page Builder Tip Issue No. 34, linked among the City's housing tips under the 2024 Ontario Building Code and dated January 1, 2025, on when 2 lb closed-cell spray foam serves as the vapour barrier. It quotes Articles 9.25.1.1., 9.25.4.2. and 9.25.4.3. on scope, the 60 ng/(Pa.s.m2) permeance limit tested to ASTM E96/E96M, and placement on the warm side. The Objective explains that 50 mm of foam can meet that limit, cautions about combining it with batts, and lists five sealing steps where the foam is the air barrier.

What it covers

9.25.1.1. Scope and Application
9.25.4.2. Vapour Barrier Materials
9.25.4.3. Installation of Vapour Barriers
Objective

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