VHP Strong Roof Underlay
VHP Strong Roof Underlay
VHP Strong Roof Underlay is a 140 gsm premium roofing underlay. It is fire retardant, high performance and highly breathable and a huge upgrade from Bitumen paper.
Manufactured from synthetic multi-laminate spun-bonded, non-woven polypropylene membranes.
Premium performance and fire retardant
Assists in moisture control - deflects water and air both during construction and as part of the finished roof
Self-supporting and strong
Highly breathable - transforms water vapour at higher rates than bitumen-impregnated paper
Temporary weather protection - UV resistance for 21 days
Scope of Use
Masons Roof Underlays are certified for use as a roof underlay and air barrier:
a) on buildings situated in wind zones up to and including Extra High (as set out in NZS3604) with a minimum roof pitch of 3°,
b) under masonry or metal tile and profiled metal roof cladding,
c) in all locations including where it is not covered by an internal lining
Masons Roof Underlay shall be:
a) installed in accordance with Masons Roof Underlay Installation Instructions Version 1.0, Jan 2021, and
b) installed run vertically or horizontally with or without support for roof pitches greater than 10°, run horizontally with or without support or run vertically with support for roof pitches less than 10°, provided that support is provided where the span is greater than 1200mm, and
c) protected from sunlight within 21 days of installation
Further details regarding the use of the product can be found in Masons Roof Underlay Installation Instructions Version 1.0, Jan 2021
NZ Building Code Provisions
B2 Durability: B2.3.1(a), B2.3.2
C3 Fire affecting areas beyond the fire source: C3.4(c)
E2 External moisture: E2.3.1; E2.3.2 (Contributes to)
F2 Hazardous building materials: F2.3.1
Health and Safety
Compliance with any manufacturer’s installation instructions, maintenance, OH & S statements, MSDS and other Health and Safety declarations will provide the necessary Health and Safety Information pertaining to the product.
VHP Strong underlay is a 140 gsm tri-laminate sheet consisting of a white non-woven top layer with black printing, a white non-woven back layer and a dark grey synthetic membrane centre layer. Both sides of the underlay sheet have an embossed pattern. The sheet is 1.45 m wide and is labelled VHP Strong Roof Underlay.
Supporting Documentation for Certification
Acceptable Solutions and Verification Methods For New Zealand Building Code Clause B2 Durability (Amendment 12), 28 November 2019
C/AS1 VM1 Protection from fire Amendment 3
C/AS2 Acceptable Solution for Buildings other than Risk Group SH for New Zealand Building Code Clauses C1-C6 Protection from Fire, 1st edition, 27 June 2019
Acceptable Solutions and Verification Methods For New Zealand Building Code Clause E2 External moisture 3rd edition (Amendment 9), 27 June 2019
Acceptable Solutions and Verification Methods For New Zealand Building Code Clause F2 Hazardous Building Materials (Amendment 3), 1 January 2017
SCION Report QT8080A "Evaluation of Uni FR FAB to NZS 2295", February 2020
SCION Report QT8222VHPM "Evaluation of Roof VHP Maxi to NZS 2295", July 2020
SCION Report QT8222VHPS "Evaluation of Roof VHP Strong to NZS 2295", July 2020
SCION Report QT8222VHPU "Evaluation of Roof VHP Ultra to NZS 2295", July 2020
L H Boulton Report 201265 "Assessment of Masons Roofing Underlays for Buildings", 21 October 2020
Masons Roof Underlay Installation Instructions Version 1.0, Jan 2021
NZS 2295 2295:2006 Pliable, permeable building underlays
NZ Metal Roof and Wall Cladding Code of Practice version 3.0
Browse downloadable product files.
1.25m x 40m = 50m²
1.25m x 60m = 75m²
1.45m x 51.7m = 75m²
Frequently asked questions about Masons Roof Underlay Strong
Is Masons VHP Strong Roof Underlay compliant?
Yes, all our roofing underlays carry a Codemark certificate of compliance
What is the roll size?
1.45m x 51.7m = 75m²
How thick is VHP Strong roof underlay?
Is VHP Strong roof underlay fire retardant?
VHP Strong, Maxi, and Ultra are all fire retardant. VHP Value is not fir retardant.
What is the maximum span without support?
All VHP Roof Underlay is self-supporting to a span of 1200mm
What is the minimum roof pitch?
All VHP Roof Underlay has a minimum roof pitch of 3 degrees
Are they safe on treated timber, ply etc.
Yes, all Masons underlays won’t react to treated timber/plywood
Are Masons VHP roof underlays compatible with all common roofing materials?
Yes, Masons roof underlays can be used with all common roofing materials
Where can I buy Masons VHP roof underlays?
Check with your local rep or our customer service 0800 522 533 and we can direct you to a local stockist