The use of direct fixed cladding has limited ability to manage water that inadvertently finds it way behind the primary cladding, so great care is required during installation to avoid ingress of water through the primary cladding. If water does penetrate the cladding, a flexible underlay, also known as a Weather Resistant Barrier (WRB) is included to provide a second level of defence. But poorly installed flexible underlays or insufficient durability of the underlay can result in water damage to the frame and elements within the wall.
The use pre-cladding is arguably a significant improvement over traditional direct fixed cladding. Separation of the underlay and frame from the primary cladding creates a ventilated cavity between the WRB (weather resistive barrier) and exterior cladding, equalising the air pressure within the external wall cavity, making the building airtight and providing superior weather-tightness. The use of pre-cladding can result quicker enclosure, speeding up the construction process.
For pre-cladding to function as an air and water barrier, sealing of the joints and flashing window and door openings is required. This can be achieved with liquid sealants, or through pressure sensitive adhesive (PSA) flashing and seaming tapes.
While self-adhesive tapes solve many sealing problems, use of lower quality seaming tapes or tapes that are not appropriate for the surfaces the tape is applied to can cause serious problems. For example, some tapes may peel off damp, cold or porous surfaces the day after installation or worse, after building completion. If this occurs, the effectiveness of the pre-cladding system is compromised.
Not all tapes are created equal and the key difference is the technology and quality behind the PSA and the resilience of the backing material.
3M has been developing pressure sensitive adhesives for 95 years and are market leaders in adhesives, including well known innovations such as 3M VHB foam acrylic tapes, which routinely replace mechanical fasteners, and even support architectural panels for exterior cladding.
3M All Weather Flashing Tape 8067 is a good choice for pre-cladding seaming and flashing due to its superior high-tack, solid acrylic pressure sensitive adhesive. The adhesive bonds to almost any building substrate, including all of the common pre-cladding materials, such as raw or coated fibre cement, plywood, oriented strand board (OSB) and gypsum based sheathing — all without the need for primers. Even damp or cold surfaces can be successfully adhered to with 3M 8067 All Weather Flashing Tape and the highly flexible and resilient backing provides superior strength over liquid applied sealants.
The durability of 3M All Weather Flashing Tape 8067 is assured for pre-cladding applications, with extensive testing and BRANZ appraisal (appraisal #775), meeting the requirements of NZBC Clause B2.3.1 (b) and additional testing to demonstrate B2.3.1 (a). In most cases, the allowable exposure time before the exterior cladding is installed exceeds that of the pre-cladding (up to 12 months UV exposure).
Additionally, 3M 8067 as part of the 3M Air Barrier range, affords superior compatibility with other sealants and membranes (including bitumen based membranes) without the need for material separation.
3M continues to innovate, with the new 3015UC ultra conformable, for faster flashing of openings.