Keen to learn more about the new requirements for insulation under the H1 standards? View our CPD webinar here.

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:

Substrate Plywood Concrete Existing Substrates Concrete with Tapered Boards or Flat Enertherm
(Nuratherm)
Plywood with Enertherm
(Nuratherm)
NPM900 or approved metal tray (B) with Enertherm
(Nuratherm)
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.

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

The Nuralite product is called Nuraply ALU. It is a roofing membrane with glass fibre reinforcement, topside finished with polyester reinforced aluminium foil and under-side coated with self-adhesive SBS modified bitumen. 

Nuraply Aluminium Vapour Barrier is applicable as vapour barrier for roofing systems in buildings with high humidity conditions (Inner climate: class IV). The datasheet is available here 

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.

Our insulation products are designed to react to fire and not spread flames, and we have strict guidelines to where they can be used. Enertherm PIR should be used for projects covered by NZS3604 or up to a wall height of 10 metres. After this height point, there is often a façade engineer involved with the cladding design and requirements for higher performing products in fire situations. Then we would recommend using the ROCKWOOL Stone Wool which is totally non-combustible and is the best choice for the taller or higher priority buildings.

We have EPDs available for both our Enertherm and ROCKWOOL products. Currently we are working on converting these documents to sqm rates to enable comparisons and will publish them on our website. 

 As a part of our Toitu Carbon Zero  Certification, Nuralite is committed to reducing our carbon footprint. 

Nuraply TPO Fleeceback is ideal for a warm roof as it bonds to the insulation, but the membrane is ‘floating’ on the fleece. This gives a smoother finish to the membrane and importantly allows vapour to dissipate across the surface so there is less chance of blisters forming. 

There are a few different loads on a roof. To counteract any down force, Enertherm PIR has a high compressive strength (175kPa) and Roofing grade ROCKWOOL would be used for its high density.  

More concerning is the upper forces on the roof as it would tear the roofing off. In this situation the critical consideration is the fixings and their pullout strength. This is a design consideration and part of the system (such as TriCore or ThermaCore) 

The insulation value of ROCKWOOL is lower than PIR, so you would need more of it to achieve the same R-value. 

Enertherm PIR is suitable for use in roofs of buildings above 10m. However, combining the two products can give the best of both world’s – enhanced fire and acoustic performance of ROCKWOOL with the PIR providing high-performance insulation with light weight and good compressive strength. 

In addition, Nuralite can assist with specification of a total non-combustible ROCKWOOL warm roof for special building types incorporating a coverboard and membrane finish.

The important thing is that the WRAP vapour retarder is installed on the warm side of the insulation. A recent determination shows what happens if the air barrier is above the insulation  https://www.building.govt.nz/assets/Uploads/resolving-problems/determinations/2021/2021-012.pdf 

The problem is one of buildability. The WRAP normally needs to be installed onto a substrate so that it is sealed. It also should join the roof WRAP to the wall WRAP. If located behind or above the Gib it would be hard to achieve this.

You can walk on a Nuralite membrane Warm roof for maintenance – Enertherm PIR has high compressive strength of 175kPa, so is not easily damaged.  

If you need a trafficable deck area, it is necessary to float a deck on Nurajacks. These distribute the load, so do no damage to the membrane roof system. 

Both plywood and metal have low vapour permeability, but sealing every joint and gap to prevent airflow though is challenging – especially at upstands and particularly with profiled metal trays. 

Particular care is required with membrane roofs as they have no airflow above the insulation to remove moisture, should it occur. Instead, the vapour will condensate between the membrane and insulation causing the facer to fail and blisters to develop.  Over time this will become a serious issue that is difficult to repair. 

We therefore strongly recommend that all membrane roofs include a quality vapour barrier. 

The Nuraply 3PV-SA base sheet incorporates a unique vapour diffusion layer on the underside of the sheet.  This “diamond” shaped partial adhesion pattern allows for any unintentional construction moister to dissipate across the surface of the roof area, eliminating potential vapour blisters in the finished membrane system. Yet another level of redundancy built into the Nuratherm Warm Roof system.

Vented Base Sheet Technical Note.pdf

152 kB | Updated: September 2021

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.

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.

Nuraply 3PM, 3PG, 3PC and 3PT/PTM have CodeMark certification, the highest certification possible in New Zealand.

The CodeMark must be consented by Councils if specified in accordance with the Nuralite install manuals.

BRANZ has provided an independent verification of the Nuraply 3PM, Nuraply TPO and Nuratherm systems as well. All reports have concluded that the respective systems meet or exceed the requirements of the Building Code.

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.

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.

Nuraply TPO, being a smooth thermoplastic membrane, is ideal for potable water collection throughout its useful life.

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. Nuraglaze helps fill the pours in the mineral chip and helps prevent mould growth and vegetation entrapment.

Greenroofs are not suitable for collecting potable water because little water gets through the soil substrate and what does may be containated by fertilisers.

For the best quality drinking water, it is highly recommended that the following are included in a water collection system:

- Install a first flush diverter. These are components tapped into downpipes that discard initial rainfall.

- Installing a tank vacuum system that automatically siphons off sediment from the bottom of the tank whenever the tank water overflows

- Install a U.V. filter.

- Install a Charcoal filter.

For more information please review Health Department guidelines. https://www.healthed.govt.nz/system/files/resource-files/HE10148_Water%20collection%20tanks%20and%20safe%20household%20water.pdf

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 tells you everything you need to know. Contact Nuralite if you would like a representative to come and discuss your options.

Nuralite Nuraply 80 Rebirth.pdf

664 kB | Updated: March 2019

Around 9kg /m2 for a double layer system.

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