ASTM D4434

ASTM D4434/D4434M, Standard Specification for Poly(Vinyl Chloride) Sheet Roofing, sets minimum requirements for PVC single-ply roofing membranes. The active version is D4434/D4434M-21.

What it covers

The specification covers flexible sheet made from poly(vinyl chloride) resin for use as single-ply roofing exposed to the weather. Under the current edition the sheet must contain reinforcing fibres or fabric. Properties addressed include thickness, breaking strength, elongation, seam strength of factory seams, tearing strength, low-temperature bending, dimensional stability, water absorption, and resistance to heat ageing and weathering.

The specification does not cover in-place roof design matters such as fire resistance and wind uplift, which are demonstrated by system testing and code compliance.

About PVC membranes

PVC is a rigid plastic, so roofing membranes contain plasticizers to make them flexible. Over many years plasticizer can migrate out of the sheet, especially in contact with incompatible materials such as asphalt or polystyrene insulation, leaving the membrane brittle. Formulation, thickness and separation layers are used to manage this. PVC membranes are heat-welded at seams and are known for good resistance to many chemicals, oils and fats, which makes them common on restaurant roofs and some industrial buildings.

PVC is one of the thermoplastic membranes (along with TPO and KEE blends) that together hold a large share of the US commercial roofing market.

Related standards

• ASTM D6878 covers TPO membranes.
• ASTM D4637 covers EPDM membranes.
• In Europe, PVC roofing membranes are specified under a harmonised European standard for plastic and rubber roof waterproofing sheets.