The Weathertight Wrap / Underlay System

Water-Proofing

All FPS® Weathertight® membranes are classified as W1 waterproof, with water column tests of between 1500mm and 5500mm (far in excess of the building code requirement of 20mm). It will not leak or wick moisture and have all passed the 24 hour water streaming test.

FPS® Weathertight® membrane wrap is able to shed liquid water, while standard building paper / roofing underlay systems can become saturated and potentially leak.

Moisture Control

FPS® Weathertight® membranes are permeable, allowing moisture vapour out of the construction during the build phase and for the life of the building. All our building membranes are considered vapour open, allowing faster drying, speeding up the build time.

FPS® Weathertight® membranes are microporous, whereas many building and roofing paper systems are not. This breathability helps prevent moisture buildup and the potential for mold and rot growth within the walls.

Wind-Proofing

The FPS® Weathertight® System is able to be used in all New Zealand wind zones, on roofs and walls (BRE Test Report 301-688 issue 2, 29th February 2015).

The wind pressures on the roof are far greater than that on the walls, please see the table to choose the appropriate product.

Air Tightness

FPS® Weathertight® is airtight and will not allow airborne moisture to enter the construction, maintaining durability and insulation performance. Standard building paper / roof underlay systems are not designed to be completely airtight. They have lower air tightness due to the material used, and have potential for gaps during installation.

UV Exposure

FPS® Weathertight® membranes are tested and certified for UV exposure for up to 90 days. UV stabilizers are incorporated into the membrane during production. These additives absorb or reflect UV radiation, extending the lifespan of the membrane material when exposed to sunlight.

Traditional bituminous building paper is often rated for no more than 7 days.

Fire Retardant

FPS® Weathertight® wall and roof membranes have an AS1530 – part 2 flammability index of not greater than 5 and therefore meet the requirements of NZBC Acceptable Solutions.

Standard building paper generally offers minimal fire resistance and is not considered a fire-retardant material according to most building codes.