What is Passive Ventilation?
Passive ventilation is a method of allowing continuous airflow into a building with the objective of eliminating condensation by removing the warm air from the roof void.
Why do we need it?
Condensation is a huge problem in NZ mainly due to poor building design. NZ weather tightness requirements have been specified for several decades without the required ventilation which causes condensation. From this, mould is easily formed which is a major contributor to the alarmingly high level of asthma and respiratory diseases in NZ.
How does it work?
In a balanced system, wind blowing over the ridge creates a negative pressure that draws the warm air out of the attic/roof space. Replacement air enters through the under eave or soffit vents, bathes the underside of the roof, and exits at the ridge cap through the ridge vent. Even with no wind, the natural convection action of rising warm air maintains a continuous airflow along the underside of the roof. It is a system that works year round with no moving parts or energy consumption.
Is it a proven solution?
Yes the systems we provide have been tried and tested across Europe & USA covering the most extreme climatic conditions. Passive ventilation has been mandatory overseas for over two decades.
Where can we use it?
There is a wide range of products covering every eventuality so they can be utilised in homes, offices, commercial buildings and are especially effective in classrooms. Tests have shown that freshly circulated air prevents students from tiring in the afternoons which produces improved performances.
Are moulds dangerous?

Spores from dried mould are very dangerous and should be cleaned with caution. Never scrape or scratch dried mould, because the spores will become airborne and create a serious inhalation risk. Most mould infested areas are relatively small and are usually the result of small leaks or plumbing problems. If the problem is more internal such as on insulation or throughout a carpet, the only solution is to have the items professionally removed before being replaced. Mouldy areas more than 600mm2 are considered “heavily infested” and professional removal is strongly advised. Some insurance companies cover the cost of mould removal or remediation under certain circumstances. Check with your insurance agent to find out if you are covered.

Is mould always visible

NO. You may suspect hidden mould if a building smells mouldy, but you cannot see the source, or if you know there has been water damage and residents are reporting health problems. Mould may be hidden in places such as the back side of Gypsum board, wallpaper, or panelling, the top side of ceiling tiles, the underside of carpets and pads, etc. Other possible locations of hidden mould include areas inside walls around pipes (with leaking or condensing pipes), the surface of walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof leaks or insufficient insulation).

Can mould cause health problems?

Moulds have the potential to cause health problems. Moulds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mould or mould spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mould are common. They can be immediate or delayed. Moulds can also cause asthma attacks in people with asthma who are allergic to mould. In addition, mould exposure can irritate the eyes, skin, nose, throat, and lungs of both mould-allergic and non-allergic people.

What to wear when cleaning mouldy areas - health & safety?

It is important to take precautions to limit your exposure to mould and mould spores.

  • The use of personal protective equipment (PPE) should be considered during a mould investigation. The primary function of PPE is to avoid inhaling mould and mould spores and to avoid mould contact with the skin and eyes. Professional judgement should be used when selecting PPE. The use of PPE is indicated when mould is disturbed and likely to become airborne during an investigation.
  • Avoid breathing in mould or mould spores. In order to limit your exposure to airborne mould, it would be recommended to wear a respirator, Some respirators are made primarily of plastic or rubber and have removable cartridges that trap most of the mould spores from entering your lungs.
  • Wear gloves. Long gloves that extend to the middle of the forearm are recommended. When working with water and a mild detergent, ordinary household rubber gloves may be used. If you are using a disinfectant, a biocide such as chlorine bleach, or a strong cleaning solution, you should select gloves made from natural rubber, neoprene, nitrile, polyurethane, or PVC. Avoid touching mould or mouldy items with your bare hands.
  • Wear goggles. Goggles that do not have ventilation holes are recommended. Avoid getting mould or mould spores in your eyes.
What is a Cold Roof?
A Warm Roof is a roof with no attic space and is generally associated with a flat roof, inclined ceiling or a mono-pitch roof design. A specific system is utilised for this type of roof.
Is passive ventilation better than mechanical ventilation?
Firstly passive ventilation is free air, costs nothing to run and requires no maintenance. Also if the mechanical ventilation has no external vent to fresh air, it will just be circulating the warm and moist air from the roof space into your home. If this is the case, mould can form inside the ducting and the spores will be circulated into your home. This can trigger asthma and respiratory diseases especially in elders and infants.
Will the vents let birds and insects in?
The mesh and grille sizes have been tried and tested and the recommended gap is set at 4mm. This has been tested to prevent the ingress of nesting insects and obviously birds and vermin. Tests show that a vent of 3mm or less can retain water and paint etc and block the airflow. Water will run out of a 4mm grille.
What does it cost to install in a home?
Passive ventilation products are mainly recycled plastic so they are extremely affordable and simple to install. Compared to mechanical ventilation, passive ventilation can cost up to 60% less with no ongoing maintenance costs.
What is the general cause of mould and how can we fix or prevent it?

Mould is generally caused by structural leaks, plumbing leaks or condensation from lack of ventilation. Structural and plumbing leaks can be fixed once identified but the lack of ventilation is often the common cause which is overlooked. All buildings need to breath so sufficient passive ventilation should be installed to the outside of the thermal envelope to prevent condensation within the roof void. Weather tightness has increased since the 1970’s without any consideration for associated and much needed ventilation. Consequently we now have buildings literally sweating which is creating mould contamination in all homes, new and old.

Fortunately we can provide affordable product solutions for all renovation and new-build projects which will eliminate condensation and provide a healthier living/working environment.

How does mould affect asthma?

Moulds can trigger asthma attacks in individuals with asthma. People with asthma and respiratory diseases should avoid contact with exposure to moulds.

What is toxic mould?

Black Mould or what is referred to often as Toxic Mould are common terms used to describe a slimy, greenish black substance which can result in a very serious health risk. While toxic black mould is less common than other mould species it is far from rare. Cellulose is the only known host for the dangerous strains of Stachybotrys and Memnoniella, which produce mycotoxins. The mycotoxins grow in damp areas. Substances where this mould can be found include places where water has soaked wood, ceiling tile, wall panelling, studs, cellulose insulation, gypsum board, carpet backing, cardboard and other items made of natural fibres such as cotton can act as a host. It can infest areas in the floors, walls and ceilings. Mould problems resulting from flooding should be treated professionally to avoid health risks. If the black mould is growing on materials that do not contain cellulose, it is unlikely that either Stachybotrys or Memnoniella are present. If you suspect Black Mould, have it tested before attempting to remove it.

What is common mould (non-toxic)?

The black mould that you may see growing on grouting and walls of showers and bathtubs is unlikely to be dangerous. The most common mould is Cladosporium. Although it can be an irritant to those with asthma or respiratory disease, it is not known to pose any toxic hazard. The most effective way to prevent it is by providing adequate ventilation. Vent fans should be installed in all areas where dampness can occur.

How can mould cleaned up?

Who should do the clean-up depends on a number of factors. One consideration is the size of the mould problem. If the mouldy area is less than about 600mm2, in most cases, you can handle the job yourself, however:

  • Avoid exposing yourself or others to mould
  • Fix plumbing leaks and other water problems as soon as possible. Dry all items completely.
  • If you already have a mould problem – ACT QUICKLY. Mould damages what it grows on. The longer it grows, the more damage it can cause to the structure of your property.
  • If there has been a lot of water damage, and/or mould growth covers more than 600mm2, contact us for further information.
  • If you suspect that the heating/ventilation/air conditioning (HVAC) system may be contaminated with mould (it is part of an identified moisture problem, for instance, or there is mould near the intake to the system), you may need the Air Ducts in Your home cleaned before taking further action. Do not run the HVAC system if you know or suspect that it is contaminated with mould – it could spread mould throughout the building.
  • If the water and/or mould damage was caused by sewage or other contaminated water, then contact us as experience will be required for cleaning and fixing buildings damaged by contaminated water.