ITP UltraPerm BBA certified roofing underlay for all pitched roof designs and timber frame wall applications.

Storage and handling:

• The membrane must be handled and stored to avoid damage and moisture. Rolls should be stored flat, away from direct sunlight inside a dry storage area.
• Use non-corrosive fixings, nails should ideally be of galvanized or austenitic steel, phosphor, bronze or silicon bronze. Staples should be of austenitic stainless steel.

Wall installation:

• Hang horizontally or vertically, fix to the outside of the frame using non-corrosive fixings.
• With SIPs panels, the membrane can be stapled to the panels.
• Upper layers should overlap lower layers in a tile effect for water run-off.
• Ensure the membrane covers the lowest framework by a minimum of 25 mm. It is essential that the lowest timbers in the wall are protected by the breather membrane. Make sure the positions of studs are marked to enable wall tie fixing.
• At external corners, return the membrane by at least 100 mm. Nail or staple the membrane to every stud, max 200 mm centres. If exposed before cladding secure with battens to prevent wind uplift.
• For airtightness use ITP Powerbond S/S Tape Acrylic or ITP Powerbond D/S Jointing Tape Butyl to seal.

Wall overlaps:

• Horizontal overlaps 100 mm minimum.
• Vertical overlaps 100 mm minimum.

Roof installation:

• ITP UltraPerm should be installed with the printed side facing outwards.
• A staple hammer may be used to position the membrane prior to final battening.
• Where the membrane is draped over rafters, in the case of an unsupported roof, horizontal laps should be covered by a batten with the bottom edge of the lap projecting less than 25 mm below the batten to ensure the edge is secured against wind uplift.
• Counter battens, where required should be at least 12 mm thick.
• ITP UltraPerm may remain unprotected for up to 2 months, recommended practice is to install tiles or slates as soon as possible to minimize the risk of water ingress.
• Please see installation instructions for specific roof installation requirements.

ITP UltraPerm is a range of high performance breathable underlays, BBA certified for all pitched roof types; warm and cold, supported and unsupported, ventilated and unventilated. ITP UltraPerm can also be used in timber frame wall applications.

Available in a choice of four grades; Lite 92 gsm, Standard 115 gsm, Premium 135 gsm and Max 155 gsm, ITP UltraPerm is tough, durable and tear resistant with exceptional water vapour permeability (breathability) and hydrophobic (water repellent) characteristics.

The ITP UltraPerm range is fully tested to the latest BS 5534:2014 + A1:2015 zones 1-5.

Use ITP Powerbond S/S Sealing Tape Acrylic to seal overlaps.

Features and benefits:

• BBA certified for roofs and walls.
• Four grades available; 92 gsm, 115 gsm, 135 gsm & 155 gsm.
• Breathable with high water vapour permeability.
• Exceptional W1 water resistance.
• High tensile strength and nail tear resistance.
• Pre-printed marking lines.
• Independently tested for full compliance with BS 5534:2014 + A2:2018.
• CE approval.
• Bespoke printing available.