Level threshold on the face of things sounds simple: a level entry where the external surface is the same height as the internal surface. However, when studying the New Zealand Building Code, specifically E2/AS1 External Moisture 7.3 level threshold, it becomes apparent there are some complex details if the external surface is created with a concrete slab. In this scenario, a channel drain is required that complies to specific specifications. To illustrate this I have summarised some key details from E2/AS1 7.3.2.1 Concrete Slab:

A channel with a 150mm minimum depth and a 200mm minimum width,

• • 1:200 minimum fall to an outlet,
  • Outlets discharging to an E1 compliant drainage system,
  • Maximum 3.7 meter channel length,
  • Paving Falling away from Channel, 1:40 for first meter,
  • Paving drainage to meet requirements of NZBC Clause E1, and
  • Grating that is;
    • Supported independently of the building
    • Removable for maintenance and cleaning
    • Has a continuous 12mm gap from building line
    • Refer to figure 17b for a sectional detail.

There are many channel drain products on the market that offer solutions to the above clause. It is worth doing a little research on these products prior to specifying as some may have complex install methods and/or be non-customisable on site. Both of these factors can result in a poor install appearance, performance and/or increased labour costs and install time. Products will often come in 1m or 2m straight lengths with a fixed width grate, however, the building line rarely follows a straight line and can step in and out around joinery. Products that don’t provide the ability to adjust the grate width will result in an increased gap where the joinery steps back. This increased gap is unsightly and may not meet client approval (for example, a daycare centre).

Whilst in the past a three sided channel may have been accepted at a threshold situation, council is becoming more and more cautious about moisture transfer and the designed operation of the glazing suite. It isn’t possible to use a three sided channel for level threshold as the building side of the channel will interfere with the intended free drainage path to the compliant channel.

Joinery is designed to direct moisture away from the building, this will be impeded by closing off this drainage path, hence the requirement for the 12mm separation and L shaped channel required by code. Some suppliers may encourage the use of three sided channel products as an alternative solution, this can lead to unnecessary admin and design complexities with the risk of not being granted. When designing an alternative solution councils will require additional hydraulic performance calculations and structural details. It may be worth considering this extra effort when off-the-shelf solutions are available. Trying for an alternative solution may delay the consent process and extend construction timelines.

There are off-the-shelf systems that can be customised to suit each varying application. These can reduce onsite labour, and minimise design time with published details and compliance documentation. An example is Allproof Industries Perimeter Drain, an L shaped channel that can be installed directly against the foundation slab. The Perimeter Drain provides the required width with additional depth for screeding a fall inside the channel towards the outlets. This system is an off-the-shelf product that can easily be customised on site. The 1m long channels can be cut to desired lengths and angles as they follow the building slab and the NZ made system of adjustable brackets and grates can also be cut on site to follow the joinery line. The use of this system will allow you to maintain a clean, consistent and “continuous gap of 12mm minimum from door frame and wall cladding”. The grate and bracket system is secure, self supporting and bolted into the channel whilst being completely removable to allow channel servicing and maintenance as required by code. The Perimeter drains L shaped channel creates the boxing for a single concrete pour, grates can be immediately installed once the finished surface is cured reducing labour and overall contractor time on site. There is also the option for custom NZ fabricated stainless grates to follow the unique building line.

Some aesthetic features may require other systems that need to be cast into or fixed to the external slab. For instance, if a reduced grate width is desired on a high-end residential property, a Cantilever Bracket or Cast-in Cantilever Bracket will provide the ideal solution to suit various external slab finishes. A Cast-in Cantilever Bracket is ideal for an exterior concrete finish while a Cantilever Bracket provides an excellent system for tiles or pavers. This system also offers the option for a tile insert grate, minimising the impact of the threshold transition by removing the visible grate. These systems are made to measure providing a fully customised solution to facilitate your vision with no compromise on the finished appearance, performance and compliance.

Allproof level threshold systems are designed and made in New Zealand. With a national support network, the offering of onsite customisable systems and custom fabrication level threshold doesn’t need to be challenging. Allproof provides a dedicated nationwide specification support team to develop the perfect solution for your project from design to install.

Level Threshold Products

Co-written with Andrew Smith, Specifications Manager at Allproof Industries.

Resources: E2 External moisture, Building Performance Systems, MBIE

Drainage systems designed and tailored to provide hygienic solutions for facilities that care for New Zealand’s most vulnerable.

According to Stats NZ, building consents issued in the preceding 12 months to May 2021 for hospitals and nursing homes increased in value by 44.5% to $711 million (an increase of $219M NZD). Educational facilities increased by over 60%, an additional $561 million. All these facilities cater to the most vulnerable members of our society. Each facility most likely contains an area for the preparation and/or serving of food; the world health organisation states “unsafe food containing harmful bacteria, viruses, parasites or chemical substances can cause more than 200 different diseases — ranging from diarrhoea to cancers. Around the world, an estimated 600 million — almost 1 in 10 people — fall ill after eating contaminated food each year, resulting in 420,000 deaths.”

A kitchen or food preparation facility therefore must perform at the highest hygienic level possible to safeguard the health of the occupants using these buildings. The success of a commercial kitchen or food and beverage production facility is made or broken on its design. Drainage design is of special importance but is often an afterthought behind aesthetics and functionality. A good drainage system contributes to food safety and hygiene, conversely, insufficient drainage can result in food contamination.

When designing commercial kitchens, off-the-shelf drainage products may not provide the best solution for the very specific needs of each application. A better approach is to understand the installation environment and assembling tried-and-tested systems with the appropriate capabilities, designed into a customised, optimal layout. This will maximise performance and economy by not under or over-engineering while benefiting from systems with proven quality and reliability.

Commercial kitchens are spaces that are subject to regular occurrences of spillage of liquid used during cooking and cleaning, as well as grease, fat and food waste. Without an appropriate drainage system, wastewater can cause pipe blockages, and major disruptions to service. Kitchens must be designed so that any liquids present on the floor or discharged from equipment are quickly and safely removed.

In a commercial kitchen, drainage can impact major aspects of the operation with food safety among the highest concerns. Food can become contaminated if wastewater is not safely drained away during food preparation and when cleaning surfaces. Good drainage systems prevent bacteria from entering into the premises, and reduce the incidence of contaminated water pooling and stagnating.

Allproof manufactures commercial drainage systems from high grade stainless steel with a variety of designs that can be tailored to suit each application. Stainless steel makes an excellent hygienic material for kitchen and food processing facilities because it contains no pores, cracks or open spaces for bacteria, including odour to embed itself in, as it is a self-contained piece of material. Its great mechanical properties mean it’s also resistant to dents and surface defects ensuring the surface remains sealed for hygienic purposes. It is also easy to maintain/clean ensuring that bacteria doesn’t have an opportunity to grow or spread.

Drainage is an important factor to consider when designing a kitchen or food preparation facility, it can be difficult if not impossible to remediate work should the installed drainage system not be sufficient for the intended purpose. It is advisable you engage the assistance of a hydraulic engineer and Allproof — a specialised drainage supplier — at an early stage to get the right customised solution.

Recent updates to NZBC E3/AS1 (Amendment 7 Nov 2020-21) have refined various requirements for containment of water in the case of accidental overflow from a sanitary fixture. These requirements are applicable if the “accidental overflow could damage an adjoining household unit or other property” and the fixture does not have an integrated overflow with a flow rate greater than the inlet/tap (and minimum flow rate of 0.25 l/s).

In the case of creating a containment area with floor waste an “impervious floor covering” is required to be:

1. 1. 1. “Continuous and covered or joints sealed where they meet the wall, and
      2. Extend to the doorway and all walls of the room, or to at least 1.5m from all sanitary fixtures and sanitary appliances in open-plan rooms.”

The floor waste shall comply with NZBC Clause G13 however a graded floor is not essential in this situation.

A scenario for this may look like an open plan kitchen in a townhouse, the kitchen floor could be vinyl or tiled with the rest of the open planned living space carpeted. If the kitchen sink is unable to satisfy overflow requirements, the kitchen floor would need to be impermeable and to span at least 1.5 metres from the sink or follow details set out for junctions with walls. A floor waste would need to be situated within this area to enable the drainage of surface water should an accidental overflow occur.

A tiled floor will require a waterproof membrane applied to a leak control flange, a floor waste gully, spigot and grate will complete the system allowing the grate to finish flush with the tiled surface. In this situation a four-way riser junction could be utilised allowing other waste systems to integrate with the drain. In an apartment or multi-storey tenancy a compact junction and gully system could be utilised such as Allproof’s Boss Gully allowing the system to sit within the available floor/ceiling cavity.

Bathrooms with sinks that don’t fit overflow specifications also require a floor waste, this practice has been well used and it is very common to see a tile insert grate under a vanity in recent projects. The same compact Boss Gully junction could be used to connect the shower waste and sink outlets into one system. For showers with limited joist space of 150mm an Easy Clean Revolver could be utilised, this is ideal for residential projects that don’t require passive fire protection. However, if you are under no space constraints a traditional floor waste gully would be recommended as less maintenance is required.

Another area for consideration would be a laundry, E3/AS1 2.1.1 b) refers to appliances and fixtures, meaning even without a sink the laundry may need to comply to containment specifications.

It is advisable to locate the floor waste in an accessible location to ensure it is maintained and primed. If the floor waste isn’t connected to other drainage systems as suggested above, the water trap/seal could dry out allowing odours to escape into the room (unless a dry floor waste is used that discharges directly outside, this is applicable only for accidental overflows and must comply to G13 3.4.3). Also, any maintenance required would become difficult to conduct, ‘out of sight, out of mind’ would be an appropriate term. Allproof have a wide range of high performing floor waste systems that are visually discreet with custom finishes to provide these spaces with an aesthetic appeal while applying to code and protecting the property (and adjoining) from moisture damage.

The primary objective of AS/NZS standards is to safeguard people from injury or illness, and property from damage. There are many elements which contribute towards this objective. Outlined are five key factors to consider when selecting the appropriate products for the job.

Application

Ensure you select the correct type of product for the job. Is a channel required or will a sump suffice? Is this a level entry into a habitable space, a channel drain in front of a drive/garage, or a collection point before going into the local authorities’ stormwater system? Each application has different requirements set out in NZBC and applicable AS/NZ Standards. A level entry scenario requires a 200 x 150mm channel and a 12mm drip line along the joinery (plus other various details), therefore a standard three sided channel is not applicable in this application. Each drainage system has been designed for a specific application, if you are unsure it is worth discussing your project with the channel supplier to avoid costly delays and work by removing a system that isn’t compliant.

Performance

Ensure that the selected drainage product’s hydraulic performance meets the needs of the application. This may be a combination of the channel depth/width and grate open area or even just how the product is set up. Understanding the topography of the area will also have a large part to play, installing a slot drain with a 15mm opening at the bottom of a steep drive means that during a heavy downpour surface stormwater will likely bridge the gap and the drain will not perform to the desired level, however, a wider grate with more open area (eg. Allproof PC with cast iron grate) would allow the water to drain. A channel slot drain would work well in a courtyard with a fall towards it from both sides. It is best practice to seek advice from a specialist hydraulic consultant in this area.

Load Rating

AS3996:2019 Access Covers and Grates outlines the requirements for grate load class ratings. Grates must perform well under subjected loads appropriate to their application once installed. The standard provides a rating of A to G with A being “areas (including footways) accessible only to pedestrians and pedal cyclists and closed to other traffic (extra-light duty)” with a nominal wheel load of 330kg, and G for “docks and aircraft pavements subject to very high wheel loads (extra heavy duty)” with a nominal wheel load of 30,000kg. The majority of applications will require a load rating between A and D which would cover commercial vehicles in areas such as loading bays. Allproof have developed in-house testing to ensure their products meet the specifications laid out by AS3996, this information is available in their literature to aid product selection.

Environment

The environment plays a large factor in material selection when choosing a product. Stormwater drainage products are exposed to large amounts of moisture by nature of the application. It is important to understand the chemical and physical characteristics of materials in each environment. Cast iron is an excellent material for strength with a long life expectancy and economic price point, and its bituminous paint coating does provide a degree of protection from the elements. However, unless regularly re-painted it will wear off exposing the cast iron and oxidation will naturally occur.

Depending on the environment this can remain for some time, in high trafficable areas it will pass quicker and will eventually stabilise into a dull dark brown patina. This is a natural material reaction to the environment, it’s aesthetic and does not impact performance. In some scenarios (laneways) this may be a desired aesthetic, but the lifetime appearance should be considered in projects where a consistent appearance is desired. Allproof recommends high grade 316 stainless steel in marine environments as it has a higher degree of resistance to corrosion and reduces the need for regular maintenance, alternatively glass filled nylon (GFN) provides a black finish that doesn’t react to the environment.

Grating Design

Considerations additional to the features discussed above include the grating open area. Open areas will affect the hydraulic performance of the system, larger open areas would generally perform better hydraulically, smaller individual open areas may be more prone to blocking from debris. However, smaller individual open areas would be advisable in pedestrian zones, Allproof have classified a range of their grates as heelproof for use in areas likely to see high levels of foot traffic. Heelproof grates are designed to resist entry of high-heeled shoes by limiting the smallest dimension for an opening to 8mm or less.

It is also advisable to consider slip resistance on grate surfaces. This can be important in settings likely to be subjected to high volumes of foot traffic for example, busy urban streets and commercial courtyards. AS 4586:2013 covers the requirements and classifications for slip resistance, a variety of Allproof grates have been tested by an independent laboratory with excellent results ranging from R9 to R13.

According to Stats NZ’s ‘Building Consents Jan 2021’ demand for townhouses, flats and units have increased by over 80% within the past two years. With increased demand for mid to high density housing and constraints on available land, designers and product suppliers have sought systems to maximise the usability of available space.

Bathrooms are being placed under increased pressure as designers look to save space in areas of the dwelling that may not be considered prime living space. The majority of townhouses have ditched the bath with preference for a shower unit instead, however a shower unit can be bulky and close in the space while detracting from the aesthetics. A solution for this would be tiled showers with an elegant glass partition, this opens up the bathroom space with a continuous floor and wall finish, with the inclusion of wall niches it can create a far more user-friendly option.

A traditional tiled shower uses a waterproof membrane system bonded to a leak control flange creating a ‘tanked’ area. Tiles are then laid over the membrane with the appropriate fall towards a channel or point drain. This system is an excellent option and Allproof has built its reputation through a wide range of products and their integration with waterproof membrane systems. However, it has become apparent that there is demand in the market for a tiled waterproof system that provides the same level of assurance as a shower tray.

A stainless steel shower tray creates an impermeable barrier below the tiles that is highly resistant to any movement within the structure. This can become an important factor to consider when creating timber framed multi level dwellings with bathrooms above ground level or any development with intertenancy levels. One scenario that highlights this decision making process is Cordis Hotel in Auckland, even as a steel and concrete structure the designer decided the initial cost of putting tile over trays in each of the 235 bathrooms outweighed the cost associated with the risk of a failure. A leak in one bathroom would ultimately affect two or more rooms with the additional rooms being on the level below, this would greatly impact the revenue stream of the hotel along with the costs of repair.

Specifying a tile over stainless shower tray also provides the assurance of performance and compliance with NZBC clause E3 internal moisture and relevant AS/NZ Standards. A tile over stainless shower tray would be considered a “Preformed Shower Base” (AS 3740-2010; 3.6) needing to be sufficiently recessed into the wall and floor allowing waterproof membranes to be dressed onto the flange surface areas (textured to maximise bonding), it should also be supported to prevent distortion or cracking. Allproof have designed the tray to exceed the minimum fall outlined for ‘Type 1’ showers (AS 3740-2010; 3.13.5) by utilising an engineered base. The tile over stainless tray provides options of a 1:80 (recommended for hob entry) or 1:50 (recommended for level entry) fall which satisfies NZBC E3 3.3.5 which looks to obtain a fall of 1:50 towards the shower drain. The tray has a channel drain built into the system with tile bar options designed to suit varying tile depths and weepage holes allowing subsurface moisture trapped by the stainless tray to track into the waste outlet.

Allproof Stainless steel tile over trays have been developed so that they can be custom made specific to each project while reducing the work and impact on the installer. Each tiled shower tray caters to the unique variables of the project including overall size, shape, entrances/wall upstands, tile depths and grate options. The tray is supplied as a complete unit with the engineered base attached. The production process consists of completing an initial custom form with measurements, Allproof will then follow up with any questions and supply a shop/production drawing for sign off. By using a system with built in fall it removes the need for screeding on site, saving time and costs. The tray is fixed into place and tiles are directly applied following the install guide. The same process can be followed for stainless steel wall niches, a recent addition to the Allproof offering.

Tile Over Stainless Tray

1. Compliance with NZ regulations

The New Zealand Building Code (NZBC) ensures Kiwis have the highest standards of health, hygiene and safety in their properties, taking into account New Zealand’s unique weather and climate conditions and user requirements. For waste and drainage systems, the objective of NZBC Clauses E2 External Moisture and G13 Foul Water is:

• • E2.1 to safeguard people from illness or injury that could result from external moisture entering the building
  • G13.1 to:
    • (a) Safeguard people from illness due to infection or contamination resulting from personal hygiene activities; and
    • (b) Safeguard people from loss of amenity due to the presence of unpleasant odours or the accumulation of offensive matter resulting from foul water disposal.

Through their accompanying compliance documents, both clauses set out expectations for the design, construction and installation of waste and drainage systems to protect buildings and occupants.

These, together with relevant AS/NZS Standards, are the main resources for the design and development of drainage products here in New Zealand, ensuring NZ based manufacturers are well-positioned to supply the local market with products specifically for New Zealand’s construction industry.

2. Local knowledge for product development

Allproof draws on insights and knowledge gained through the company’s 33-year heritage of partnerships and collaborations with top New Zealand plumbers, hydraulic engineers, architects and industry bodies, such as Master Plumbers.

By utilising these relationships, Allproof has been able to grow and maintain a large product portfolio based on the critical feedback and insights from the New Zealand construction and plumbing community. Products such as the Tile Over Stainless Tray have eliminated the need to screed a fall into the tray hence reducing work needed on site to install. Once again this process was all possible thanks to the product feedback from the construction and plumbing industry.

With a New Zealand-based team of over 100 tradespeople, machine operators, engineers and operations staff, Allproof’s ongoing product development programme is well equipped to implement the feedback creating innovative systems for the plumbing and drainage industry in a fast-paced and challenging climate.

This process means products have been developed with the installer in mind and the unique challenges of the New Zealand building design and construction industry they face on-site every day.

Tile Over Stainless Tray

3. Investment in manufacturing processes

New Zealand’s plumbers and drainlayers want systems that perform to the highest standards and stand the test of time. Knowing that continuing investment is being made into production processes and controls gives installers confidence that products are fit for purpose in the work they are completing (reflecting back on the core objectives of the NZBC and AS/NZ Standards).

Allproof consistently invests in their manufacturing processes to control all aspects of product production and to maintain a high level of quality across the range. Engineers maintain and develop moulds in the company’s fleet of injection moulding machines, whilst a department of 30 fabricators use some of the industry’s most advanced technology to ensure accuracy and quality in Allproof’s stainless steel drainage products.

4. Accessible technical advice and assistance

Easy, first-hand access to product advice and assistance is another key advantage to using NZ made. With an in-depth understanding of the applicable Building Code clauses and Standards, Allproof’s NZ based sales team of eight are able to provide in-depth technical insights and advice for the application of the company’s drainage and waste products.

The team has a range of skills and backgrounds, including plumbers, builders and staff who have been with the company for over 12 years. The sales team help designers select and design drainage systems specific to projects, visit sites to provide technical information and installation training and to assist with measurements where possible.

5. In-house design for customised systems

Commercial projects often have unique requirements that benefit from purpose-designed drainage systems. Drawing on industry and technical knowledge, Allproof’s in-house design team are able to design drainage systems that cater for project-specific scenarios. This full in-house design service is unique to Allproof and allows the company to supply custom-designed systems with high drainage performance that cater to each site’s limitations and install requirements. Allproof has been at the forefront of the shower channel product design with our custom stainless steel Vision Shower Channel, utilising linear drain options we are able to customise the channel length for project specific jobs.

The stainless steel fabrication department then manufactures these systems to the highest level of accuracy and, before being dispatched, all products must pass a Quality Assurance process from a QA dedicated team member.

Vision Shower Channel

The Ministry of Education released Version 3.0 of Designing Schools in New Zealand – Weathertightness Design Requirements for New School Buildings in September 2020. This document is aimed at architects and designers by outlining the acceptable details for weathertightness around level threshold access. This is an important factor when considering the intended use of an educational facility and those requiring access.

MoE’s Weathertightness Design Requirements provide clear details in section 6.4 Threshold Channel Details for which a level threshold installation must comply to. “The threshold channel must be designed as ‘dry in service,’” meaning the external surface must fall away from the channel with a minimum slope of 1:50. The threshold channel must have a clear internal width of 200mm and have a minimum depth of 150mm at the high point of an internal fall. The grate is to have a clear 150mm width, maintain a 12mm separation from joinery and/or cladding and be easily removable for maintenance. There must be no more than a 20mm level change between internal and external surfaces to meet NZBC and NZS4121 accessibility requirements.

The channel must “be laid with minimum 1:200 falls to a sump connected to the stormwater system” with outlets set at 3700mm centres for uncovered areas or 7400mm centres for “suitably sheltered” areas as per Clause 6.3.4 regarding covered verandas, overhanging upper storey or recessed doorways. Figures 6-4, 6-5 and 6-6 show details of how the channel interacts with cladding which is a detail not previously covered in E2/AS1. Cladding is to be finished 50mm above grate level with a concrete nib or it can be taken down below the grate surface with the use of impermeable moisture resistant cladding and only in “suitably sheltered” areas as per Clause 6.3.4.

The document states “three-sided pre-formed channel systems are prohibited,” meaning Allproof’s Perimeter Drain is the solution. Perimeter Drain is a two sided channel with a bracket system supporting a grate allowing for the 12mm drip line. The bracket is anchored using fixings embedded into the channel wall, the bracket system maintains a mechanical separation from the joinery meaning it doesn’t rely upon the sill for support. The Channel provides a set 200mm width and is 180mm deep catering for a 1:200 screeded fall in the base of the channel. This easy to install system complies to all of MoE’s Weathertightness Design Requirements and E2/AS1 standards.

This system was developed at Allproof Industries manufacturing facility on the North Shore of Auckland. Allproof manufactures a variety of level threshold systems to suit all manner of applications. A rigorous design process coupled with in-house and independent testing facilities for load rating and slip resistance ensure Allproof’s products are of the highest standard for performance and safety.

Allproof level threshold products have been used in educational facilities all around New Zealand and notably the below projects:

• AUT Auckland City
• King’s School Remuera
• Northcote Primary
• Long Bay High School
• Stonefields school
• Waiheke School
• Sunnyfields School
• Meadowbank School

Perimeter Drain

A short guide to designing an external surface water drainage system that protects your dwelling from moisture while maintaining visual consistency and high performance.

A typical residential project will likely require various surface water drainage systems installed at the property entrances and at the property boundary to protect the building from moisture and mitigate runoff into the street. Each scenario will have different requirements based on its performance needs and applicable building codes. The following describes typical scenarios you may face and how these systems would converge before surface water can be drained into the local authorities stormwater system.

Garage and Driveway Drain

For attached garages (areas not deemed to be habited spaces) the door openings will have a “50 mm minimum total level change between the interior and the exterior paving” (E2/AS1 clause 9.1.3.4) in the way of a nib and/or ramp, a drainage channel would then be installed across the total opening width. The same channel drainage system would likely be present at the driveway entrance along the property boundary to collect runoff from the property. Factors to consider would be channel depth, load rating and grate selection. When selecting a grate for a low traffic area that will be subjected to vehicles it is advisable to consider the likelihood of grate dishing and ongoing material finish (i.e. oxidisation in cast iron). Allproof’s Domestic Channel system is constructed from high grade plastic and is suitable for domestic vehicles by gaining its strength from the surrounding concrete. The Domestic Channel’s plastic grates appearance lasts and maintains shape under repeated wheel loads. If a higher load rating as per AS3996 is required in the situation where commercial vehicles or heavy loads such as boat trailers need to access the property, Allproof’s Polymer Concrete would provide an excellent alternative. Grade 316 stainless steel Wedge Wire (load class B or above) would make an excellent grate option in this situation.

Domestic Channel

Polymer Concrete

Level Threshold Entry

At the main entrance to the dwelling a level threshold may be desired where the internal surface and external surface are not subjected to a level change, in this scenario E2/AS2 clause 7.3.2 applies. A 150mm deep by 200mm wide channel is required across the entrance with a grating system that will maintain a 12mm separation (drip line) from the joinery. A traditional 3 sided channel doesn’t work in this scenario as the joinery traditionally overhangs the building slab and will often vary in its width creating a narrower reveal in certain areas. Features to consider here would be the grate finish/material and slip resistance in accordance with AS4586. Allproof’s Perimeter Drain provides an off the shelf two sided channel solution for this with an adjustable Glass Filled Nylon (GFN) grate or a fully custom stainless steel grate supported by a bracket. The GFN grate has a matte black finish which compliments dark joinery and has an R10 slip rating whilst the 316 grade stainless steel Wedge Wire grate is made to measure by Allproof and offers an R11 slip rating. Allproof also offer a wide range of other fully custom manufactured systems to accommodate for a variety of other design variables, for more detailed information on designing the correct system and application for level threshold please see our article on How to Design E2 Compliant Level Access Building Entrances.

Perimeter Drain

Sump/Collection Point

Round Drainage Pits

In a central or practical location a sump should be installed. This sump can be used to drain the surrounding surface area by creating falls towards it and therefore positioned accordingly, or it can be used as a collection point for the property’s other drainage systems. The sumps purpose is to provide suitable collection capacity for surface water from the surrounding area, provide sediment catchment while removing the likelihood of floatable solids entering the stormwater system and provide access for maintenance and cleaning. E1/AS1 states in clause 3.6.1 that “all surface water, except that collected directly from a roof, shall enter the drain via a sump which has:

1. 1. 1. A grating, hinged or removable for maintenance access. The grating shall comprise at least 35% openings. The smaller dimension of any individual opening shall not exceed 35 mm,
      2. Capacity at the bottom for settlement of silt and debris, and
      3. A submerged (or trapped) outlet which prevents floatable solids entering the drain”

The channel systems previously highlighted all have outlet locations on the underside of each channel section, stormwater pipe would then drain the collected surface water away from the building and into the above sump. Allproof’s DP350x700RS has recently been brought to the market, the sump complies to the above E1/AS1 clause 3.6.1 with a round cast iron grate, 300mm of sediment collection and enough space above to include a half syphon outlet.

The Full System

Other drainage systems such as Allproofs Storm Series grates may also be required depending on the design of the property, these will follow a similar process and integration with the full system. A level of continuity can be achieved by selecting complementary systems from the same supplier, often grates and details are transferable between products allowing for an aesthetic language to be kept throughout the project.

Modern building design places an emphasis on maximising useable space in smaller footprints, therefore design features such as open-concept bathrooms have become popular to extract maximum value from the space available. By removing a boxed in shower unit in exchange for a tiled shower, the space can become drastically more usable.

There are certain aspects to AS/NZS standards and the NZBC E3 that must be accommodated for during the design and install of a tiled shower. Ensuring that water is retained within the designated shower area is important, this will predominantly be controlled with the combination of walls, doors and fall in the floor towards an outlet.

Most residential showers will be considered a ‘Type 1’ (according to AS 3740-2010; 3.13.5) with a frameless glass screen, shower curtain and/or waterstop hob entry controlling splash and surface water. Therefore, a minimum of 1:100 fall is required where a hob is present. A minimum of 1:80 fall is needed for all other shower areas. By designing a shower with a channel drain (typically running along the back wall under the showerhead), the installer will only need to screed a fall in one direction, this then improves the aesthetic finish and reduces the amount of work conducted by the tiler by avoiding crosscuts through the tiles towards a central point drain outlet. AS 3740 states “it is advisable to have either the screed drained or a membrane placed on the top of the screed to prevent retention in the screed beyond the water stop.”

New Zealand’s wide offering of waterproof membranes combined with Allproof’s drainage systems such as the Vision Shower Channel creates some excellent options to protect the structure of the building from moisture created within this area. For those who prefer the assurance of a shower tray/base being present, especially in bathrooms located in timber structures or multi-storey buildings, an Allproof stainless steel shower tray can be installed under the tiles creating an impermeable barrier directly under the wet area.

A tile over stainless shower tray would also be considered a “Preformed Shower Base” (AS 3740-2010; 3.6) needing to be sufficiently recessed into the wall and floor allowing waterproof membranes to be dressed onto the flange surface areas (textured to maximise bonding), it should also be supported to prevent distortion or cracking. Allproof have designed the tray to incorporate the fall outlined for Type 1 showers by utilising an engineered base. The tile over stainless tray provides options of a 1:80 (recommended for hob entry) or 1:50 (recommended for level entry) fall which satisfies NZBC E3 3.3.5 which looks to obtain a fall of 1:50 towards the shower drain. The tray has a channel drain built into the system with tile bar options designed to suit varying tile depths and weepage holes allowing subsurface moisture trapped by the stainless tray to track into the waste outlet.

The Allproof preformed Tile over tray system makes tiled showers easy while providing peace of mind for installers by creating a system that accounts for the required falls, provides a reliable impermeable base, removes the need to screed, allows for direct stick tiles and flat floor framing. Tile Over Stainless Trays are custom made in New Zealand to project-specific measurements, a custom quote/order form can be downloaded from allproof.co.nz.

Tile Over Stainless Shower-Tray

Since opening its doors Commercial Bay has been a key topic of interest in the A&D community earning it a position among the finalists for one of the industry’s most prestigious awards. With 300 metres of level threshold skirting the perimeter Warren and Mahoney along with Fletchers had to carefully select the correct supplier and product to cater for such a complex and varying application. NZBC E2 has set out strict criteria that level threshold drains must adhere to for performance and safety reasons. Due to the scale of commercial activity, foot traffic, plus the variety of joinery systems selected, the level threshold drain needed to be highly adaptable while maintaining the level of detail and aesthetic that Warren & Mahoney are renowned for.

Allproof Industries’ Perimeter Drain was selected as the ideal solution. Allproof manufacture drainage and passive fire systems on the North Shore of Auckland and specialise in custom stainless steel systems. The Perimeter Drain uses a polymer concrete L shaped channel with a variety of off the shelf and custom grate options. This system allows for varying joinery dimensions that step in and out overhanging the channel by adjusting the grate width for a clean channel line around the perimeter of the building. On Commercial Bay certain areas at secondary entrances have wider spans of grate to accommodate for the building line, the system needed to be engineered for load rating on these areas to cater for traffic that is specific to these entrances. Allproofs Wedge Wire grate was selected for its customisable features, excellent hydraulic performance and R11 slip rating.

The transition between the Sky Lobby and the roof top terrace uses a revolving door, Allproof were asked to create a custom stainless steel drainage channel to the exact radius of the door allowing for level entry onto the terrace. Allproof’s Threaded Leg system with wedge wire grate was ideal for this. Allproof used the specifications from the door supplier to laser cut a stainless template to the required radius, this template was then tested on site to ensure the correct fit. Allproof’s fabrication team then used the template to hand fabricate the system rolling each element of the grate to the exact diminishing radius before welding the components together creating the full system.

Allproof was also chosen for the drainage system running down the centre of the retail complex. The channel drain is installed as a podium set up with restricted depth due to the City Rail Link (CRL) line and station below the complex. A 75mm depth channel was therefore selected with the outlets directed into podium flanges below the surface. A heelproof cast iron grate for its durability, performance and aesthetics has been used, the characteristics of cast iron combined with high levels of foot traffic means that it will weather into the environment and blend with and enhance the laneway atmosphere the architecture creates.

By selecting a New Zealand manufacturer Commercial Bay significantly benefited from specialised knowledge in the NZ building code that Allproof were able to supply, along with a product range specifically designed for the local market and the ability to highly customise bespoke systems to the exact needs of the project.

Threaded Leg

Perimeter Drain

200mm Opening Polymer Concrete

100mm Opening Polymer Concrete