mdm Ventia Iron Roof and Wall Underlay Installation Guide

: June 9, 2024
: mdm

Table of Contents

mdm Ventia Iron Roof and Wall Underlay
ROOF UNDERLAY INSTALLATION PROCEDURE
WALL UNDERLAY INSTALLATION PROCEDURE
Contact Information
References
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mdm Ventia Iron Roof and Wall Underlay

mdm-Ventia-Iron-Roof-and-Wall-Underlay-product

ROOF UNDERLAY INSTALLATION PROCEDURE

Installation must always be carried out in accordance with the Ventia Iron Roof & Wall Underlay technical Literature or under the supervision of a Licensed Building Practitioner with the relevant License Class.
Ventia Iron Roof & Wall Underlay has been appraised for use as a flexible roof and wall underlay for timber and steel framed buildings. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $1$$
Ventia Iron Roof Underlay must be fixed at a maximum of 300mm centers to all framing members with large-head clouts 20mm long, 6-8mm galvanized staples, self-drilling screws, or proprietary underlay fixings such as Lumberlok Little Grippers. The underlay must be pulled tight/taut without creases over the framing before fixing. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $2$$
Ventia Iron Roof Underlay is suitable for use at roof pitches 3° and above. When used at pitches less than 10°, Ventia Iron Roof Underlay can be installed horizontally or vertically when fully supported by a corrosion-resistant material (steel mesh). At pitches 10° and greater, Ventia Iron Roof Underlay can be installed vertically or horizontally when the span is no greater than 1200mm between supports.
Ventia Iron Roof Underlay must not be exposed to the weather or UV for a total of more than 7 days before being covered by the roof cladding. NZS 2295, the Building Code standard for roof building underlays, gives guidance that the roof underlay needs to be covered within seven days.
Ventia Iron Roof Underlay is suitable for use in all Wind Zones of NZS 3604 up to, and including, extra high.
It must extend from the ridge and overhang the fascia board by 20-25mm. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $3$$
Vertical and horizontal overlaps must be no less than 150mm, with the direction of the overlap ensuring that water is shed to the outer face of the underlay. End laps must be made over framing and be no less than 150mm.
When fixing the product in windy conditions, care must be taken due to the large sail area created.
Any damaged areas of Ventia Iron Roof Underlay, such as tears, holes, or gaps around service penetrations, must be repaired. Damaged areas can be repaired by covering them with new material lapping the damaged area by at least 150mm and taping or by taping small tears. For taping, use high-adhesion flashing tape ViBest Super Pro.
The Technical Literature must be referred to during the inspection of Ventia Iron Roof Underlay installations.

WALL UNDERLAY INSTALLATION PROCEDURE

Installation must always be carried out in accordance with this document. Where the work has Consented Building Work, the product must be installed by (or supervised by) a Licensed Building Practitioner with the relevant License class.
Ventia Iron Roof & Wall Underlay has been appraised for use as a flexible roof and wall underlay for timber and steel framed buildings. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $4$$
Ventia Iron Wall Underlay must be fixed at a maximum of 300mm centers to all framing members with large-head clouts 20mm long, 6-8mm galvanized steel staples, self-drilling screws, or proprietary underlay fixings such as Lumberlok Little Grippers. The underlay must be pulled taut (tight) over the framing before fixing.
In cavity installations where the cavity battens are installed at greater than 450mm centers, the wall underlay must be supported between the battens to prevent the underlay from bulging into the cavity space with polypropylene strap, 75mm galvanized mesh or galvanized wire or cavity battens.
Ventia Iron Wall Underlay must be run horizontally and must extend from the upper side of the top plate to the underside of the bearers or wall plates supporting ground floor joists, or below bottom plates on concrete slabs. Horizontal laps must be no less than 150mm wide, with the direction of the lap ensuring that water is shed to the outer face of the membrane. End laps must be made over framing and be no less than 150mm wide. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $5$$
Ventia Iron Wall Underlay should be run over openings and this left covered until windows and doors are ready to be installed. Openings are formed in the membrane by cutting on a 45° diagonal from each corner of the penetration. The flaps of the cut membrane must be folded inside the opening and stapled to the inside of the penetration framing. Excess underlay may be cut off flush with the internal face of the wall frame. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $6$$
When fixing the product in windy conditions, care must be taken due to the large sail area created by wide roll widths.
Ventia Iron Wall Underlay must not be exposed to the weather or ultraviolet light for a total of more than 90 days before being covered by the wall cladding.
Handling and storage whether on or off-site, are under the control of the installer. The rolls must be protected from damage and weather, they must be stored on end, undercover, in clean, dry conditions, and must be not crushed.
Ventia Iron Wall Underlay is supplied in rolls of 2.74m wide x 36.5m long (100m²) and rolls of 1.50m wide x 50m long (75m²) and wrapped in clear polythene film.
Any damaged areas of Ventia Iron Wall Underlay, such as tears, holes or gaps around service penetrations must be repaired. Damaged areas can be repaired by covering them with new material (underlay) overlapping the damaged area by at least 150mm and taping with ViBest Super Pro flashing tape 150mm wide. Small tears and holes can be repaired with ViBest Super Pro flashing tape.
The Technical Literature must be referred to during the inspection of Ventia Iron Wall Underlay installations.
Staple the corner molds into the sill and jamb junction of the frame. A length of ViBest Super Pro flashing tape must be cut to the length of the sill and 200mm up each jamb. The overhanging tape is cut at the corner of the opening to allow the tape to be folded onto the face of the Wall Underlay at a minimum of 60mm.
Cut another length of 75mm wide ViBest Super Pro Tape of the exact length of the sill and overlay it onto the already installed tape to ensure nail seal-ability requirements are met. $mdm-Ventia-Iron-Roof-and-Wall-Underlay-fig- $7$$
A second layer of 75mm wide ViBest Super Pro flashing tape must be installed along the entire length of the sill.
When the tape is used on a door opening with a wooden sill, the installation is the same as for windows and if the sill is concrete, it is only required to be 200mm across the concrete sill.