3 long years of a persistent La Niña in South-East Australia has unfortunately made everyone intimately more familiar with damp and mould in their homes and even in their workplaces.
Although we cannot control the weather, we can control building design. Builders need to be encouraged to make strategic design and product choices that allow occupants to keep the rain out while also providing adequate ventilation to prevent condensation and keep buildings dry.
The drive for making buildings increasingly weather tight over recent decades has not been fully coupled with strategies that allow for our buildings to effectively dry out and stay dry.
This has led to buildings being designed and built with inadequate passive ventilation of the roof spaces and cavities. The consequence of which is moisture related damage to structures and the health of occupants.
The term "NCC 2022" refers to the National Construction Code of Australia, which is a set of regulations that provide the minimum requirements for the design, construction and performance of buildings in Australia.
The NCC is regularly updated to reflect changes in technology, building materials, and construction methods, as well as to address new concerns related to safety, health, and sustainability.
The most recent changes to the NCC 2022, will come into effect on May 1st, 2023, with new condensation management and mitigation requirements commencing October 1, 2023. In the meantime, NCC 2019 Amendment 1 remains applicable.
Problems of damp, mould and condensation are so pervasive that the NCC 2022 outlined 2 key changes to address this specific problem.
- Use of vapour permeable membranes such as those supplied by Proctor Group Australia. The wide range of roof sarking and wall wraps are highly watertight replacing the perforated “foil with holes” wraps and both foil sarking and foil faced blankets for the roof.
- Use of passive ventilation to remove moisture from our roof space to keep our roof spaces both drier in winter and cooler in summer.
Roof spaces, particularly in cool climates, are at increased risks from condensation. NCC 2022 requires roof spaces in these climates to be provided with ventilation openings.
Considerable amendments have been made to the roof ventilation requirements in NCC 2022, specifically in climate zones 6, 7 and 8 which includes Western Sydney.
Although not mandatory in climate zone 5 these are still good practice measures for addressing condensation risk.
Tables F8D5 in NCC Volume One and 10.8.3 of the Housing Provisions provide the requirements for ventilation openings for roofs with varying pitches and minimum requirements for:
- the location of sarking and/or the primary insulation level relative to roof space
- the minimum roof space height, and
- what is deemed adequate ventilation for a roof space to minimise condensation risk.
|ROOF TYPE||REQUIREMENT OF AIRFLOW
NATIONAL CONSTRUCTION CODE 2022 VOL 1 F8D5 / ABCB HOUSING PROVISIONS STANDARD 10.8.3
|PROCTORVENT PRODUCT COMBINATION|
|Roof Pitches <10°||25,000mm²/ Lm at each of two opposing ends||FV25 and RR650|
|Roof Pitches ≥10° & <15°||25,000mm²/ Lm at eaves 5,000mm²/ Lm at ridge/high level||FV25 and RR650 RV10P/DT or RV10P/DT HALF|
|Roof Pitches ≥15° & <75°||7,000mm²/ Lm at eaves 5,000mm²/ Lm at ridge/high level||FV10, RR650 RV10P/DT or RV10P/DT HALF|
|Cathedral Roof ≥15° & <75°||25,000mm²/ Lm at eaves 5,000mm² /Lm at ridge/high level||FV10, VB20 RV10P/DT or RV10P/DT HALF|
Over Fascia Vents FV10 / FV25
|The FV10 & FV25 ProctorVent Over Fascia Vents are designed to discreetly ensure airflow into the roof space between the roof membrane and the fascia board of 10,000mm² and 25,000mm² per linear metre respectively.
These products are ideal for both new build and re-roofing situations. For all cathedral roof situations the larger ProctorVent FV25 should be specified.
|PROCTOR VENT EAVES BAFFLE
Ventilated cavity Batten VB20
|The ProctorVent Eaves Baffle Vent is designed to create a 25mm air gap between the top of the insulation and the underside of the roofing underlay to ensure unimpeded airflow through the eaves into the roof cavity.
Insulation batts can then be installed into the eaves, above the wall plate without gaps or stepped down layers.
The ProctorVent Eaves Baffle Vent improves insulation performance by reducing wind-washing of glass fibre insulation and losses from missing insulation.
|PROCTOR VENT ROOF BATTEN
Ventilated Roof Batten VB20
|VB20 Roof, is a strong, durable 20mm cavity batten that is designed to ensure that unimpeded airflow through the roof cavity of a cathedral roof design.
The VB20 is easy to install and comes with self-adhesive backing for ease of temporary fixings to metal or timber roof battens.
Ridge Vent RV10P/RV10DT
|The ProctorVent Ridge Vent is designed to release air from the roof void roof as part of a passive ventilation system that works year round with no moving parts or energy consumption using the natural convection, or by means of negative pressure created by wind blowing over the roof.
The ProctorVent Ridge Vent is a discrete replacement for traditional rotary driven (whirlybird) vents. Unlike traditional vents, ProctorVent Ridge Vents are continuous and do not require penetration to the roof cladding and will be covered by ridge capping / flashings once installed.
The RV10P & RV10DT have an adhesive and flexible aluminium flashing which forms to roofing profiles, preventing water ingress.
The RV10P is designed to be compatible with roof cladding profiles with a trough depth of less than 34mm. The RV10DT is designed to be compatible with most roof cladding profiles with a trough depth of 34mm and over.
Drainage Batten DB-FR
|The ProctorVent Drainage Batten (DB-FR) is a high compressive strength drainage batten manufactured from a fire retardant polyolefin extrusion providing air and vapour movement and a pathway for drainage between the sarking and the roof cladding.
DB-FR allows for roof roof sarking to be installed without direct contact to the roof or wall cladding thus reducing conductive heat transfer between the roof and the structure and reducing localised condensation risk on the interior face of the underlay.
Australian Standard AS 3959 : 2018 (Construction of buildings in bushfire-prone areas) contains specific requirement for the treatment of ventilation openings. These requirements depend on the specific BAL Zone.
The ProctorVent ridge vents, fascia vents and ventilated cavity battens are available, wrapped in ember guard made of non-combustible corrosion-resistant steel mesh with a maximum allowable aperture of 2 mm, conforming with Clause 3.6 of AS3959:2018 and suitable for up to BAL29. Note that for BAL40 and BAL FZ there may be further requirements.
|Limited Combustibility, Class 4 Vapour Permeable, Water & Air Barrier Sarking for Bush Fire applications.
A2 (PyroPerm-A2) is a three-layer membrane consisting of a thin vapour permeable, air tight and water resistant film protected by a woven non- combustible glass textile on one face and a highly perforated aluminium film on the other.
Developed as a Class 4 vapour permeable sarking for use in bush fire zones, PyroPerm-A2 offers a combination of strength, limited combustibility, and high-water holdout without compromising vapour permeance.
No1 Roofing & Building Supplies are proud suppliers of Proctor and DCTech products