The vast majority of homes across New Zealand have mistakenly been built without the provision of calculated roof ventilation. With increasing ‘weathertightness’ being the design focus over the last 30 years, thousands of homes are now ‘sweating’ which creates internal moisture leading to structural decay and a range of respiratory health problems.

We provide a range of products which can be incorporated into existing homes to provide continuous airflow which will eliminate/reduce condensation in the home.

Soffit Ventilation – G700

Soffit Ventilation – G700 Soffit Ventilation – G700 Diagram

The Manthorpe G700 Circular Soffit Vents can be utilised for new build projects but are most commonly used as the easiest solution for existing soffits on houses with condensation problems. Standard fixing for this product is a simple push twist action into a 70mm hole drilled in the soffit board. The vent features evenly spaced 4mm slots small enough to prohibit large insects gaining access but wide enough not to be blocked by debris, paint or water droplets. This product should be used in conjunction with the Eaves Vent (EV25) to ensure continuous airflow into the roof void.

Full Product Info

Eaves Ventilation – EV25

Eaves Ventilation – EV25 Eaves Ventilation – EV25 Diagram

The EV25 Eaves Ventilator performs two functions: 1) It creates a moisture barrier between the roof underlay and the insulation. This prevents any contact with moisture & condensation. 2) It ensures a continuous airflow from the soffit vents into the roof void. This area is commonly blocked by the roof insulation.

Installation – If the pitch of the roof is shallow, a telescopic grabber (used for picking up litter) can be used by pulling back the existing insulation and placing the tray on the wall plate. When the insulation is placed back it will hold the tray in place.

Full Product Info

Ridge Ventilation – RV10P

Ridge Ventilation – RV10 Ridge Ventilation – RV10 Diagram

The RV10P Ridge Vent is designed to draw the warm air from the roof void by negative pressure. It can be used on a skillion roof or cold roof with a pitch over 30 degrees. It is designed for steel roofing and when used in a renovation situation, there will be a requirement of replacing the ridge capping to allow the air to be released.

Installation – Remove existing ridge capping and cut the roofing underlay to ensure a minimum 50mm gap as shown left. Place the RV10P centrally along the length of the ridge, over the top of the roof cladding and peel off the release film to the adhesive aluminium flashing. Fix new ridge cap without soft edge flashing over the RV10P (as shown in Products – RV10P)

Full Product Info

These are the quickest and most cost efficient methods of providing continuous airflow to the roof void. With a renovation project, it is not always as easy to achieve the recommended volume of airflow as dictated for new-build projects. Some existing roofing designs can be complex and create difficulties so the rule of thumb is that some ventilation is better than none. In this case, for renovation projects, we can only recommend following the stipulated airflow calculation guide on the product page as closely as possible as any air circulation will decrease the problem.