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New Zealand's
most specified
torch-on membrane
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designers for
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If you can't find an answer below, ask us a question.

What thickness and surface of Plywood is required?

The plywood must be:
  • No less than 17mm thick for roof areas and 21mm thick for deck areas.
  • CCA treated H3.2 grade. Do not use LOSP-treated (light organic solvent preservative) or CuN treated (copper nitrate) plywood.
  • A minimum standard of ply is C-D. The C grade upper face should be sanded and plugged.
  • Panels shall be tightly butted together and laid with staggered joints (brick bond).
  • Plywood shall be laid with the face grain at right angles to the supports.
  • The maximum span of supporting structure should be 600mm centers for beams and nogs.
  • The edge of sheets shall be supported with dwangs or framing - tough and groove plywood is not a substitute for this.
  • A 20mm triangular fillet shall be used at the base of any 90° upstand and any sharp edges must be arrised.
  • Plywood must be fixed:
    * using a suitable glue adhesive and;
    * with countersunk head, grade 316, 10g x 50-60mm stainless steel screws at 150mm centres on edges and 200mm centres in the body of the sheets.
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What are the Minimum Drainage Falls for Nuralite membranes?

The falls outlined in our CodeMark certificate must be accepted by Council provided the membrane is being installed in accordance with our Installation Manual.

The CodeMark falls are:

  Cold Roof Warm Roof (Nuratherm)
Substrate Plywood Concrete Existing Substrates Concrete with Tapered Boards or Flat Enertherm
Plywood with Enertherm
NPM900 or approved metal tray (B) with Enertherm
Minimum Finished (Constructed) Falls
1:80 1:80 1:80 1:80 1:80 1:80
Recommended Design Fall (excluding gutters) (A)
1:40 1:60 1:60 Confirm no ponding areas 1:60 1:40 1:40
Gutters 1:100 1:100 1:100 1:100* 1:100 1:100
Substrate Comments Using 17mm (roofs) or 21mm (decks) plywood, rafters at 600 centers, nogs at 600 centers. Create required slope with a screed. Wait for concrete and screed to cure. Confirm substrate is sound *Minimum fall available using tapered boards is 1:60. Nuralite can assist with tapered board layout.
Create required slope in the plywood Create required slope in the NPM900

A)    For the purpose of this Certificate roofs must have a minimum finished constructed fall of 1:80. To provide for construction tolerances it is recommended (but not required) that for design purposes, a 1:40 fall should be used on plywood and metal substrates or 1:60 for concrete.
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How do I Covert Falls/Slope?

The fall is most commonly expressed as a ratio, such as 1 in 80, or as an angle, although it is sometimes convenient to describe it in terms of a percentage slope where by definition 1 in 100 is 1%. This is convenient for calculation as it expresses the fall in centimetres per metre run.

The relationship between falls, angles and percentage slope is indicated below:

Fall ratio Slope angle % Slope Rise in mm over 1m
1 : 120 0.5° 0.8% 8
1 : 100 0.6° 1.0% 10
1 : 80 0.7° 1.3% 13
1 : 60 1.0° 1.7% 17
1 : 40 1.4° 2.5% 25
1 : 38.2 1.5° 2.6% 26
1 : 28.6 2.0° 3.5% 35
1 : 19.1 3.0° 5.2% 52
1 : 14.3 4.0° 7.0% 70
1 : 11.4 5.0° 8.7% 87
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What is the installed weight of NURAPLY 3PM per square metre?

Around 9kg /m2 for a double layer system.
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What about using NURAPLY in high wind zones?

No problem when installed properly. NURAPLY has performed in typhoon and hurricane zones such as Taiwan and Vanuatu for many years. On request Nuralite can confirm wind uplift designs for specific projects.
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Is Roof-Space ventilation necessary?

In a Nuratherm warm roof situation ventilation is unnecessary as the insulation is designed to encapsulate the entire roof system.

If using a cool roof system then yes cross flow ventilation is required. Ventilation of timber roof spaces, particularly skillion roofs, has always been recommended by Nuralite to assist with removal of interstitial moisture and mitigate high temperatures in the ceiling cavity.

The method for creating cross flow ventilation is a design consideration. A practical and unobtrusive way is using soffit vents. Alternatively we supply a purpose designed Nuravent which is installed on the roof itself. Nuravents

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What causes vapour bubbles under membrane roofs?

Vapour comes mainly from trapped moisture. NURAVENTS and Soffit Vents help avoid the problem, as does the NURAPLY 3PV ventilating system, our spot-fixed membrane specially developed for concrete surfaces which allows even greater vapour mobility.
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What Warranties apply?

The standard NURAPLY 3PM material performance warranty is for 20 years. The product applicator will provide a separate workmanship warranty. Customers should ensure they receive both of these from their applicator at the completion of the job.
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What will be the future maintenance needs?

Periodic Inspections
The building owner should establish a periodic inspection programme. The inspection should concentrate on high-risk areas such as hatches, drains and around all roof top equipment, as well as a general inspection of the entire roof. Inspections should also include the examination of the roof deck if possible from the underside for evidence of leaks, deteriorated decking, structural cracks or movement and other deficiencies. Parapets and edging should also be examined for evidence of cracking, deterioration and moisture infiltration.

It is a warranty requirement that the roof has a full inspection by an approved applicator every five years. This should provide peace of mind that the system is performing well.

Cleaning, Maintenance and Repair
Location, traffic level, effective drainage, and service use will dictate maintenance requirement.

Once a year the roof should be inspected and, if necessary, swept clean and washed down with a hose and broom, not water blasted.

Particular attention should be paid to areas where ponding water is present. Ponding water causes dirt buildup and can lead to the premature breakdown of coating systems.

As with any coating system, Nuraply 3P with Nuracolour will require recoats during the life of the Nuraply 3P system. Depending on environmental factors and the quality of the roof maintenance programme the coating will need recoating between every 5 and 10 years.

Redressing the NURACOLOUR Gel surface requires cleaning, followed by a new application of NURACOLOUR RECOAT.

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Can we collect drinking potable water from a NURALITE system roof?

Nuraply 3PM membranes have been independently tested to meet NZ standards for potable water collection.

For Nuraply 3PM a glaze coating is recommended which will require replacement during the life of the building.

In accordance with Health Department guidelines, we recommend installing a filter and using a first flush diverter so that only clean water is collected.

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Are Nuralite systems independently verified?

Nuraply 3PM has CodeMark certification, the highest certification possible in New Zealand. The CodeMark ensures the systems are consented by Councils if specified in accordance with the Nuralite Install Manuals.

As well, BRANZ has provided an independent verification of the Nuraply 3P(M) and Nuratherm systems, and the Joyce Group has reviewed the Nuradeck system.

All reports have concluded that the respective systems meet or exceed the requirements of the Building Code.

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What can I do to renew my old Nuralite roof?

Nuralite roof systems have a long life expectancy. However, at some point it is worthwhile considering tiding it up with a coating system or "rebirthing" it by laying a fresh membrane system over the existing one.
We also strongly recommend considering insulation at this point. Nuratherm can be installed over the existing membrane to bring the entire roof system up to modern standards.

The document "Nuralite Sheet Membrane & Nuraply 80 - Care, Maintenance & Rebirthing" (PDF 589KB) tells you everything you need to know. Contact Nuralite if you would like a representative to come and discuss your options.

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What fastening should I use with Aluminium tubing if making a floating deck?

The fixings should be Wintec Countersunk 10g Galvanized Steel class 4 available from Fortress Fasteners. The Aluminium Tube should be 40mm x 50mm 3mm thick tube. Using this the joist can comfortably span 1 m between Nurajacks.
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