Thermakraft COVERTEK 405 Roof and Wall Underlay Installation Guide

COVERTEK 405 Roof and Wall Underlay

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Specifications

• Product Name: Covertek 405

• Type: Self-supporting roof and wall underlay

• Material: Microporous water-resistant film sandwiched between
  two layers of spun-bonded polyolefin

• Features: Fire retardant, absorbent, breathable

Product Usage Instructions

Roof Application

Covertek 405 is designed for use in long-run metal roofing with
vertical or horizontal installation methods. Follow the guidelines
below:

• Roof Pitch: Check the span and underlay
  support requirements based on the pitch.

• Application Tips: Ensure proper ventilation
  for solvent-treated timber. Allow a minimum of 7 days for solvent
  chemical to flash off.

Corrugated Roofing

For corrugated roofing, ensure horizontal installation and
prevent ponding of water within a span of no more than 1200mm.

Concrete/Metal Tile Roofing

When installing concrete or metal tile roofing, maintain a lap
line of 11550mm. Follow the manufacturer’s guidelines for
fastenings and overhang limits.

Wall Application

When using Covertek 405 for wall application, securely fasten
the underlay and prevent bulging into the drained cavity. Use
Thermakraft window flashing tapes for window flashing systems.

FAQ

How long can Covertek 405 be exposed to weather during

construction?

Covertek 405 can be exposed to weather or UV for a maximum of 60
days. It provides temporary weather protection during construction,
allowing work to continue. Internal linings and insulation should
not be installed until the exterior cladding is completed.

What is the recommended spacing for stud straps in wall

applications?

Use 25mm Thermakraft Stud Strap or Thermastrap horizontally at
300mm centres if required, or under the guidance of a licensed
building professional.

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INSTALLATION GUIDE

COVERTEK 405
Self-supporting roof and wall underlay
Kingspan Thermakraft Covertek 405 is a premium synthetic roof and wall underlay designed as a means of managing condensation, water vapour transfer and water ingress. It is self-supporting, stable and shrink resistant and can be installed in applications where the roof pitch is 3° and above.
Product usage
Covertek 405 is a synthetic self-supporting roof and wall underlay designed as a means of managing condensation, and water ingress in roof and wall applications. Constructed using a microporous water-resistant film sandwiched between two layers of spun-bonded polyolefin Covertek 405 is fire retardant, absorbent and breathable.

Appraisal No. 743

CMNZ30030

Covertek 405
Self-supporting roof and wall underlay

Roof Application Method
Long-run metal roofing/vertical or horizontal installation method
· Fix Covertek 405 underlay with printed side facing the exterior.
· Fix using stainless steel 8-12mm staples or 20mm flat head clouts, or appropriate proprietary fastenings on timber framed structure. Fixing at 300mm centres. Fixing types and requirements for steel framed structure can be found in the NZ Metal Roof and Wall Cladding Code of Practice.
· Refer to table below to determine underlay support requirements.

Roof Pitch
10°

Span

Underlay Support Required
Horizontally Vertically Installed Installed

1200mm

Yes

Yes

1200mm

No

No

< 10° > 1200mm

Yes

Yes

(Min 3°)

1200mm

No

Yes

· Covertek 405 upper sheet lapped over lower sheets (shiplap) to ensure water is shed to the outer face. Note: Covertek 405 can move downwards. To prevent this, it must be “Captured” by the fastenings at each purlin. Horizontal fix must not be used on purlin distance greater than 1100mm to allow for 150mm laps.
· Must be laid firmly (tight/taut) without creases. All laps either vertical or horizontal must be a minimum of 150mm lap.
· When underlay support is required, Kingspan recommend using AUSMESH Safety Mesh, AUSNET hexagonal netting or Thermastrap 201. Note: Commercial Buildings may require the use of Roof Safety Mesh under Covertek 405. Covertek 405 can be installed above the battens or purlins for profiled metal roof claddings and otherwise in accordance with NZBC E2/AS1.
· If required to achieve a lap seal (refer to the NZ Metal Roof and Wall Cladding Code of Practice), use Thermakraft Premium Joining Tape or any Thermakraft Window Flashing Tape.

· Covertek 405 will provide temporary weather protection during construction (maximum 7 days), same day coverage recommended. DO NOT over expose the product for more than 7 days.
· Covertek 405 may be unwound to the full length from the gutter to the ridge. However, when ridge ventilation is required Covertek 405 may be terminated or slit at the ridge purlin to allow a free passage of air.
· Covertek 405 must NOT overhang the gutter line by more than 20 mm, or if eaves flashings are used, terminate on the upper side of the flashing. More details can be found in the NZ Metal Roof and Wall Cladding Code of Practice.
· Flue penetrations must have a minimum distance of 50mm from Covertek 405 (refer to the NZ Metal Roof and Wall Cladding Code of Practice 10.11.5 and the flue supplier’s instructions).
· Covertek 405 must be free of tears and punctures, fit tightly and be lap taped around all penetrations (except flue penetrations), to provide drainage for any condensation, or surface water from leaks.
Note: Do not use Aluband on penetrations where Polybutene water pipes have been installed. Refer to Pipe Manufacturers for instructions on sealing penetrations.
Concrete/Metal tile roofing · Covertek 405 must be laid over rafters prior to fixing
the tile battens. The maximum span between rafters for Covertek 405 is 1200mm. Masonry tile roofs must have antiponding boards in accordance with NZBC E2/AS1 Paragraph 8.2.5. · Installed Covertek 405 may be laid over the top of the antiponding boards and draped into the gutter by no more than 20mm. · Covertek 405 must be installed by, or under the guidance of a licensed building practitioner.
Application Tips
Unaffected by LOSP or other solvent based treated timber. However, LOSP or other solvent based treated timber must have sufficient time for the solvent chemical to flash off in a well ventilated area. Recommended minimum 7 days.

Covertek 405
Self-supporting roof and wall underlay

Corrugated roofing:
CCoOvVeErRteTkEKrun hrounrizhoonritzaollnytally

Concrete/metal tile roofing:
Tile roofing
Concrete/Pressed Steel Tile

11550mm LappLLiinneess
Covertek must be installed in a manner that prevents ponding of water and span
Covertek 405 must be installed in a manner that prevents ponding of water and span no more than 1200mm.
Long run metal roofing:
Wooden construction Profiled Roofing
Fastenings as per roofing manufacturer

Max 20mm overhang
Anti-ponding board
Tile roofing
150mm Lap Lines

COVERTEK Rafter or Truss Batten
COVERTEK laid horizontally over rafters

COVERTEK Rafter or Truss Purlin

Rafter

Max 20mm overhang Steel construction

Ausmesh Roof Safety Mesh

Metal tile installation
Fastenings as per roofing manufacturer
Underlay

150mm Lap Lines

Wall Application Method
· Fix Covertek 405 underlay with printed side facing the exterior.
· Fix to all exterior walls from below bearers to the top plate. Pull the Covertek 405 underlay tight and fix securely to the frame with fasteners such as galvanized Little Grippers, 6mm-8mm staples or 20mm large head galvanized clouts at 300mm centres horizontally and vertically. Additional fasteners should be used around each opening to be cut out.
Continued over…

Covertek 405
Self-supporting roof and wall underlay

· Fixing types and requirements for steel framed structure can be found in the NZ Metal Roof and Wall Cladding COP.

securely fastened. Thermakraft window flashing tapes are recommended as the window flashing system.

· When fixing Covertek 405 underlay to Steel framing

· Note: In accordance with NZBC Acceptable Solution

the same procedure applies, use adhesive spray or

E2/AS1, wall underlay must be prevented from

tape or flat head screws to fasten to the framing or

bulging into the drained cavity. Where stud spacing

thermal break. The exterior cladding fastenings will

is greater than 450mm Thermakraft stud strap or

act as the permanent fixings.

Thermastrap run horizontal at 300mm centres is an

· Fastenings behind Brick Veneer Cladding must have

acceptable means of prevention.

an equivalent service life to that of Brick Veneer (50

· Once installed, Covertek 405 must not be left

years). Refer to NZBC Clause B2.3.2.

exposed to the weather or UV for a maximum of

· Covertek 405 underlays are available in widths of

60 days. Covertek 405 underlays will provide some

2550mm and 1250mm.

degree of temporary weather protection during

· Cover all windows and door openings with Covertek 405 underlay.
· It is recommended that the Covertek 405 underlay is not cut and prepared for window installation until the arrival of the windows. Minimum of 150mm is required at joins, all vertical laps must be made over studs. Horizontal laps to be laid ship lap style allowing

construction allowing work to continue. Internal linings and insulation must not be installed until the exterior cladding is completed.
· Make good any forced tears with Thermakraft window flashing tapes. Any large areas which require repair may be covered with a second layer of underlay – a lap of 150mm is required.

water to be shed to the outer face of the membrane.

· Lap taping can be done with Thermakraft

Wall framing shown as dashed lines

25mm Thermakraft Stud Strap or Thermastrap horizontally at 300mm centres if required

Premium Joining Tape or any Thermakraft Window Flashing Tape. · Covertek 405 underlay must be installed by,

or under the guidance of a licensed building

practitioner.

Application Tips

Unaffected by LOSP or other solvent based treated timber. However, LOSP or other solvent based treated timber must have sufficient time for the solvent chemical to flash off in a well ventilated area. Recommended minimum 7 days.

Cavity battens

150mm overlap at stud

· When windows and doors are ready for installation, the Covertek 405 underlay covering the openings should cut at 45° and folded into the opening and

Handling and Storage
Covertek 405 must be handled with care to prevent damage such as tearing and roll deformation. The product must be stored under cover well away from direct moisture, rainfall contact and sunlight (UV). Care should be taken not stack other materials on top of the product.

I ue 4.0, April 2024

Appraisal No. 743

CMNZ30030

0800 806 595 www.thermakraft.co.nz
Thermakraft and Ausmesh products are brought to you by Kingspan Insulation NZ Limited.

The recommendations contained in Kingspan’s literature are based on good building practice, but are not an exhaustive statement of all relevant information and are subject to any conditions contained in the Warranty.

All product dimensions and performance claims are subject to any variation caused by normal manufacturing process and tolerances. Furthermore, as the successful performance of the relevant system depends on

numerous factors outside the control of Kingspan (for example quality of workmanship and design), Kingspan shall not be liable for the recommendations in that literature and the performance of the Product, including its

suitability for any purpose or ability to satisfy the relevant provisions of the Building Code, regulations and standards. Literature subject to change without notification. Latest documentation can be found online. E&OE.

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