In New Zealand, the weather does not give buildings an easy life. Coastal wind, driving rain, humid summers and cold winter nights all test the layers hidden behind cladding and roofing. That must be why so many people search for building paper, builders wrap, building wrap, builders paper, house wrap, housewrap, wall wrap, wall underlay, building underlay and underlay options before a project gets too far down the track. The good news is, these are all referring to the same product: a weather resistive layer protecting the frame and insulation.

These well-searched terms point to the same practical question: what should sit behind the cladding to help keep the frames dry, the insulation effective and the home durable and comfortable for decades?

Traditional building paper has been used in New Zealand construction for a long time. It sits behind the exterior cladding as a secondary line of defence. If wind-driven rain gets past the cladding, the building paper or wall underlay helps direct water back out rather than letting it soak into the structure. The New Zealand Building Code clause E2 focuses on preventing external moisture from causing undue dampness or damage caused by water accumulation.

That job is important, but it is not the whole story. A high-performance wall underlay system also needs to manage wind, vapour, installation inaccuracy, UV exposure during construction and the critical junctions around windows, penetrations, corners and roof-to-wall interfaces. While avoiding too much technicality here, just managing the wind fully will make an enormous difference to the weathertightness of a building. We know this from hours and hours of testing of products, observing how water moves through cladding, and specifically how water can’t be driven through a building where it has a well-sealed wall underlay. The only way to achieve this is with the wall underlay taped together at joins, sealed at all junctions, sealed to windows, and sealed at the base of the wall.

For that reason, modern NZ projects increasingly look beyond basic building paper products and towards complete weathertightness and systems, not just single products.

A house wrap product is easy to think of as a single roll of material, but the building envelope works as a system. If the wall wrap is torn, poorly taped, badly lapped or not connected to adjoining membranes, wind and water can still find a path through.

Pro Clima focuses on complete weathertightness systems, not just individual rolls of building wrap. For external walls, SOLITEX EXTASANA^® is a weather resistive barrier (a wall underlay) designed to protect the structure from wind, driving rain and external water while still allowing internal moisture to escape. It also has strong UV resistance and provides up to 180 days of weather protection. This is valuable when cladding installation is delayed on busy NZ building sites. When installed as part of Pro Clima’s Early-Close-In (ECI) system, SOLITEX EXTASANA^® provides both reliable construction-phase protection and programme flexibility, allowing interior work to begin confidently before cladding is installed.

For projects where a fully adhered solution is needed over a rigid substrate, SOLITEX EXTASANA ADHERO^® provides a self-adhesive weather resistive barrier for walls and roofs. This product has a full layer of adhesive and can be especially useful for prefabrication, and taller buildings or exposed sites where wind speed demands more robust weathertightness. SOLITEX EXTASANA ADHERO^® is robust, but when designing, all the wind force can be considered to land on the rigid wall underlay, e.g., plywood, OSB, external grade plasterboard, or fibre cement. A common use in New Zealand is over SIP (Structurally Insulated Panels) and is usually applied in the factory, and over CLT (Cross Laminated Timber), easily applied in the factory, and often onsite as soon as panels are joined together.

When comparing building paper, builders wrap or wall underlay products in NZ, look beyond the square-metre price. The better question is: how will this product perform once it is installed as part of the whole envelope?

Consider a building underlay that:

• resists wind-driven rain;
• allows moisture drying to the outside;
• withstands UV exposure during construction; can be taped and connected in a continuous system;
• has suitable accessories for windows, penetrations and junctions;
• is supported by technical documentation and local guidance.

Even the best house wrap or wall underlay can underperform if it is poorly installed. Laps, penetrations, fixings and window and door openings deserve careful planning. On high-exposure sites, those details become even more important.

Pro Clima’s resources are positioned around practical guidance, airtightness, moisture management, building science and technical product information. Before specifying or installing, it is worth checking the Construction Details Library, Downloads, Specifications and Product Catalogue. Builders and designers can also explore the Technical Articles. While certification is not mandatory to install pro clima products, Certified Professionals have spent time training with us. This knowledge comes into its own for projects where detailing, airtightness, or moisture control need extra attention.

For teams wanting to improve site practice, the hands-on installation workshops or building performance seminars could be useful next steps. See the availability of courses, seminars and workshops for construction industry professionals on pro clima’s Events page.

The phrase building paper is still widely used, and many people in NZ will keep searching for building paper when they begin researching. But today’s best-performing homes need more than a generically named layer behind the cladding.

They need a holistic envelope strategy: a durable exterior wall underlay or roof membrane to manage weather, and connection products that make the system continuous. For external walls, start with SOLITEX EXTASANA^®. For self-adhered wall and roof protection, consider SOLITEX EXTASANA ADHERO^®. For roof applications, think of SOLITEX MENTO^® range of roofing underlays. And for projects that need early weather protection, explore Early-Close-In with SOLITEX EXTASANA^®.

A better building wrap is not just about keeping rain out on day one. It is about helping New Zealand homes stay dry and durable for the long run.