Waihohonu Hut Tongariro National Park

By Graham Hepburn

Wellington firm Pynenburg and Collins Architects has designed about 70 tramping huts for the Department of Conservation (DoC) in the past 11 years. And in that time they have created a manual for huts that accommodate up to 40 people, including standard designs for twobunk, four-bunk, six-bunk, 10-bunk and 12-bunk huts. “Our hut manual has the procurement process, design information for challenging  environments such as alpine and coastal, drawing and specification details, means of compliance and how to build it,” says Ron Pynenburg. “It says this is what it will be built of and these are the facilities it will have.”

But the Waihohonu Hut, on the Central Plateau, like other larger huts being built along this country’s designated “Great Walks”, and other popular tramping areas has unique, site-specific features.

Because it is more aimed at families and tourists – rather than hardcore back country trampers – it includes a few more comforts, and the design is also site-specific.

“We wanted to get a view out of the living spaces of Ngauruhoe and Ruapehu so that’s why the building is a boomerang shape,” says Ron. “The two mountains are the key focus for that hut so it really needed to relate to them. We plotted the mountains into our CAD machine so we could stand inside the hut and know that we could see the mountains.

Picture windows in the living area afford those mountains views, and there are also decks outside where trampers can enjoy the scenery, something that is not normally a feature of older huts.

“With our huts we don’t want them to be just a place to stop at night,” says Ron. “They are a key part of the tramping experience because of the way we have linked them to the location. The larger huts should inherently have a sense of place so that if you see them or you are in them, you know where you are.” The hut is also oriented to gain maximum warming from the sun, keeping it warm and dry but also making it a light, bright and pleasant environment that visitors will tend to look after more.

Waihohonu is also quite large, with 28 bunks as well as staff quarters and roomy communal spaces. Ron says a hut above the bushline such as Waihohonu would normally have robust metal cladding and roofing because it can withstand the elements with little maintenance, thus reducing DoC’s costs. But on this job some ply and batten cladding was introduced for aesthetic reasons and because DoC staff can easily access the site to maintain the timber.

“Because of the size of the hut we wanted to break down the bulk of it so we used a mixture of metal
cladding and ply and batten,” he says.

The building is designed for higher than normal windloads and snowloads and is stepped along the contour of the site not only to keep it out of the weather but also to tuck it into the landscape for aesthetic reasons. The roofing and cladding colours – Ironsand and Lichen respectively – were chosen to help blend the building in with its surroundings.

Initially Colorcote® ZMXTM was not specified however Roofing Industries firmly believed this was the right roof cladding in a harsh environment known for potential Geothermal activities. By analysing and estimating alternative products Roofing Industries were able to demonstrate that a lower roofing cost did not offer the same long term protection and economy as Colorcote® ZMXTM.

Terry Slee, DoC’s project manager on the job, says the decision to clad and roof with Colorcote® ZMXTM – which is typically used in corrosive environments such as Rotorua - was based more on its longevity than
any worries about damage from sulphur fumes.

“Long-term that product offers lower costs and that’s why we chose it because sulphur’s not a problem in that part of the park unless you get an eruption and the fallout from it.”

Terry says the hut, which is on the Tongariro Northern Circuit at an altitude of about 1100m, replaces the nearby 1970s Lockwood-style hut, which was having issues with ground movement. It had been strengthened about 10 years ago to give it a new lease of life but the decision had been made to build a
new hut, in line with the policy of gradually upgrading all the Great Walks huts.

He says sustainable features such as passive solar design, beefed-up insulation and double glazing were
important to incorporate as they not only make the hut more comfortable but cut the amount of fuel needed
to keep the hut warm. And that’s important when all your supplies – including firewood – have to be
helicoptered in.

A woodburner with a wetback warms the hut and provides back-up to the solar hot water. The hut also has solar panels on the roof and a battery bank and inverter to power essentials such as lighting.

The hut has two lobbies where wet tramping gear can be hung to keep moisture out of the communal areas
and bunk rooms. Ron says vents in the gable ends act as a powerless ventilation system by creating a
stacking effect that means moist air is moved out of the hut.

All the features incorporated in Waihohonu add up to make for a much more enjoyable stay. And Ron, more than anyone, knows how huts can contribute to the tramping experience. He has been tramping
around New Zealand for 35 years, and takes great pleasure in his work for DoC.

“I’m a tramper from way back and I’m more than happy to be putting something back in.”

Pynenburg & Collins Architects This practice is led by three directors/ principals in registered architects
Ron Pynenburg, Ken Collins and Tim Burns, who are supported by a team of architects, technicians and
interior designers. With extensive experience and knowledge in design, documentation and construction,
Pynenburg & Collins aims to deliver a first class built environment by working with their clients as a team.

Architect: Pynenburg & Collins Architects,
Telephone: 04 473 7577

Engineer: Mike Cathie,
CHP Consulting,
Telephone: 04 384 9591

Builder: Miles Helberg,
Forest Hills Construction,
Telephone: 06 328 4525

Roofing contractor: APV Plumbing,
Palmerston North,
Telephone: 06 326 9342

Roofing supplier: Roofing Industries,
Palmerston North,
Telephone: 06 353 8480

Roofing: ColorCote ®ZMX.TM

Roofing Profile: Roofing Industries Corrugate

Roofing colour: Ironsand

Cladding Profile: Roofing Industries Corrugate

Cladding colour: Lichen


Solar panel 1 March 2012 Solar waters heaters – NZMRM’s preferred installation methods

Stuart Hayman.

NZMRM Technical committee Introduction Solar water heaters are an increasingly popular way of “getting
something for nothing” from nature, and if you ignore the purchase and installation costs, you do indeed
reduce your water heating bills significantly. By how much depends on how the panels are oriented.
Unfortunately, incorrect installation can result in damage to your roof, leaking into the house, and durability failure. Since even optimal installations still have around a 20-year payback, getting any of this wrong rather nullifies any benefits of the system. If your roof corrodes out in 10-15 years the cost of replacement of even part of it will outweigh the savings of your cheaper hot water.

Now all of this is reasonably wellknown (although looking at the number of bad installations, not as well-known as it should be) and DBH have provided installation methods in G12/AS2 (2007) and the Guideline Document (2009), and BRANZ have covered this topic in Build 115 (2009/2010) and a thorough investigative report SR 184(2007).

None of these really address the specific concerns NZMRM have for installation onto metal roofs and particularly longrun metal roofs. What we have said several times is that roof damage resulting from incorrect installation will not be covered by the manufacturer’s warranty. A recent installation on a new DOC hut deep in the back blocks of the North Island looks like it could have many good installation features. We have not been able to inspect the details of this rather palatial-looking hut’s installation, but
since a good installation would look quite like this, we have chosen to use this example to illustrate key
features of a “metal-roof-friendly” installation. Most of these comments apply equally to photo-voltaic solar
electricity generators that come in panels.

Key factors for protection of the roof

  • Type and weight of installation
  • Ability for roof underneath to be washed by rain or manually
  • Support of panels by roof support structure, not by the roof cladding
  • Method of support of weight
  • Correctly made penetrations for support and pipes and for efficiency and durability of the installation
  • Orientation to the sun
  • Correct insulation of pipes


A – type – evacuated tube type – cylinder inside – relatively light weight

B – supported off roof to enable limited nonroof orientation

C – clearance to allow rain and manual washing

D – rail supports not point

E – roof penetration of mounting

F – water pipe penetration - insulated Solar panel article Page 2 March 2012

A – type and weight

This appears to be an evacuated tube collector with a small header tank and the cylinder inside the building. This is a lighter weight system and the individual tubes will allow some rain washing of the roof underneath. This is a good choice from our perspective. PV panels weigh even less and present no weight issues.

B and D - support

The weight of the collector should be supported by the roof support structure, not just by being fixed to the roof cladding itself. The method of screwing willy-niily a bracket into the roof, supporting one-quarter of the weight (a leg at each corner) can damage the roof cladding in several ways – corrosion, denting allowing
water ponding, and interference with movement.

We want to see that the support goes through the roof cladding into a purlin,or purlin/rafter, which can take the weight of a collector panel provided the cylinder is inside the building or separately supported from underneath.

If the collector just has leg at each corner it may well not coincide with the structure members underneath. For this reason the support rail is preferred, as shown in G12/AS2 etc.

This allows the support bolts/ screws to be mounted over the support members underneath the roof. It also allows the rear of the panel to be elevated to provide better orientation. This is particularly important for pv panels. Mounting the panel from support rails allows more easily the 100mm minimum washing clearance
required by NZMRM between the roof and the panel.

Rails and supporting members must be made of materials / finishes of good durability, but which will be compatible with the roof. For most metal roofs this means hot dip galvanised or zinc coated and painted.

C - Raising the panel at the rear, as well as providing almost certainly better orientation (see later) to the sun, allows much better access for rain-washing and if the panel is raised by 100 mm at the front and more at the rear may remove the need for manual washing altogether. This requires the rail to be fixed at a minimum of four points front and rear.

E – Method of support fixing and penetration

As mentioned above, the fixing should be into the purlin, or the side of the rafter. G12/AS2 suggests several methods for this, of which this is one, which also shows the use of a boot flashing on the crest of the roof cladding, so that the support bolt/stud is securely fixed and its penetration of the roof cladding is water-tight.

Metal tiles use small section battens and supports should always be fastened to the rafters not just to the battens.

Obviously any panel raised above the roof, and particularly if at an angle requires to be attached well enough to resist local wind forces.

PV panels weigh less and could be supported from a purlin.

F – Water pipe penetration

Penetration of pipes through all types of roofs, when installed after the roof, is typically the point at which common sense and respect for other people’s work seems to be abandoned. Penetrations for water pipes for solar water heaters (or electric cables for pv panels) is a good example of how rushed or plain inadequate workmanship can create problems later (in some cases, not much later). BRANZ report SR184 of 2007 surveyed a number of solar water heater installations and found not a few examples of bad workmanship, including this aspect.

The method of putting a pipe or cable through a metal roof is well documented in E2/AS1, the NZMRM COP and elsewhere. While large pipes and ducts are not quite so simple, the small diameter pipes and cables required here are very simple.

For solar panels one or possibly two pipes would seem to be the maximum required in one area, so the practice of forcing a number of pipes through one hole, with liberal silicon sealant, is unnecessary. Two other factors that can ruin even a good penetration quite quickly are corrosion and insulation.

The BRANZ report shows a number of examples of how not to do it. Many of the pipes used for these applications are copper. Copper runoff onto a metal roof (unless it is also copper) is not allowed by any
legislation or by NZMRM. Since this contains hot water it is normal to insulate the pipe from the collector to the penetration. This is commonly done with a closed-cell foam sleeve. This protects the roof from run-off because the pipe is not exposed to the rain. Unfortunately most of these insulating materials are subject to quite rapid UV degradation, and when this occurs the insulation is lost and the copper run-off can occur. Since it is always black the heat gained assists the degradation process.

BRANZ recommends that the insulation should be painted with compatible paint of the same colour as the roof to avoid both problems. So, provided you do all of these things, which are not actually more expensive or difficult than doing the installation incorrectly, you should have a solar collector which functions well, does not blow away in the wind and does not damage the roof cladding – which is usually more expensive then the solar collector. Such an installation would look pretty much like that on the DOC hut. Let’s hope theirs actually has all these features as well as looking like it.

However there is one non-roof related feature to think about –


Both G12/AS2 and the Guidance Document provide tables showing the effect on efficiency of solar gain from orientation vertically and horizontally. Interestingly they are not identical, and the GD table shows 10° steps not the 20° of G12/AS2. What both of these show clearly is that 95-100% efficiency is only gained by a very tight band of orientation in both horizontal (inclination) and orientation (angle towards due North). Efficiency of as little as 45% can be the result of getting these both wrong. Since the payback for  installation depends heavily on efficiency, surely this is of key importance? And yet, almost without exception, a panel just following the roof orientation and inclination will have much less than optimum performance. The correct inclination mean for NZ is 40° and orientation due geographic North (which differs from magnetic by about 23°). What chance is there of the roof panel achieving these? Probably
very little on a typical house. What the tables Solar panel article Page 4 March 2012 do suggest is that within a band of “about North” the inclination is more important than orientation. The raised rear type of panel above, and preferred by NZMRM offers the opportunity of getting this right, or more right and even of adjusting the inclination during the year. It doesn’t look as if the DOC hut panels are at 40° does it? Maybe they could be altered. Final thought Why aren’t solar panels mounted on the ground on adjustable stands?
No weight in the roof, thermo-siphon movement of hot water, no leaking and perfect orientation.

Final thought

Why aren't solar panels mounted on the ground on adjustable stands? No weight in the roof, thermo-siphone movement of hot water, no leaking and perfect orientation.



milford sound is one of the most popular tramping destinations in New Zealand but the remote location brings with it a number of problems, not the least of which is power. Calder Stewart Roofing, Tansley Electrical and PCC donated materials and man power to provide a self sustaining solar powered system
for lighting and radio transmission. At the heart of the system is Solar-Rib®

In late 2008, Calder Stewart Roofing, a privately owned New Zealand company, launched a new state of the art roofing profile called Solar-Rib®. This product features the use of a unique photo voltaic laminate, which produces continuous electrical power from the sun. What makes this product unique is its ability to be installed into ordinary roofing situations without the need of any additional foundational support, making it a first in the industry. Solar-Rib® roofing and its laminate technology are set to become a common
addition to new and remodelled buildings across New Zealand. Solar-Rib® is ideally suited for remote locations and powers the lighting system here at Dumpling Hut. Solar-Rib® takes advantage of a wide variety of lighting conditions, producing 50 watts peak per m2 whether it’s fine, sunny, cloudy or raining. Twenty square metres of laminate can produce over 4KWh of electricity per day. This energy can be used locally (as it is at Dumpling Hut) or in other situations be fed directly back into the main power grid to be made available for wider use.

With support from the Department of Conservation, the re-roofing of Dumpling Hut, with the new Solar- Rib® profile, commenced on Monday the 15th March 2010 and was completed and operational for the opening, by the Conservation Minister Kate Wilkinson and Invercargill Member of Parliament Eric Roy, on Friday the 19th March 2010.

The time frame was critical, and given the various constraints the project had, organising the logistics and materials to site was no simple task.

“All the flashings were pre cut and all materials and tools were air freighted to Milford Sound airstrip.” says Tony Frew, Project manager for CS Roofing Southland. “Purpose made clamps, secured to strops, were attached to a helicopter that made three 20 minute trips into Dumpling Hut.”

Together with a team from DOC work began on a Monday however work on the hut was restricted by the coming and going of trampers using the hut. Nothing could be done until the hut was cleared after breakfast and had to stop as trampers arrived back at around 5.30pm.

“One of the issues that had to be tested prior to installation was unique to the location. Keas. It was unknown to what extent Keas, with their inquisitive (and destructive) nature, would present a problem with the Photovoltaic panels. A test rig was organised at Mintaro Hut prior to going on site and fortunately this proved successful. Not an issue our northerly counterparts have to worry about!” says Keith Ivey, Managing Director CS Roofing.

Kea have been responsible for short circuiting and even destroying power supplies in remote locations, but
the Solar Rib® design and robust ColorCote® roof foiled all attempts by the parrots to undermine it.

“Overall the team did very well despite one wet day and time constraints the project was completed and up and running on the 19th March as scheduled for the official inspection.”

Pacific Coil Coaters

ColorCote® by Pacific Coilcoaters Ltd has been one of New Zealand’s leading brands of pre-painted roofing and cladding products for more than 30 years. PCC is proud both to have donated the original coil roofing material for Dumpling Hut (a stop on one of the greatest walking tracks in New Zealand) and to have been associated with Calder Stewart Roofing Ltd and their new Solar-Rib®¨ roofing profile. We see it as a model for “The Roof of the Future” - and look forward to its wider use, providing environmental protection and sustainable energy for some of New Zealand’s harshest climates.

Tansley Electrical

Tansley Electrical donated the Solar Powered Lighting installation at Dumpling Hut, Milford Sound. The installation consisted of the following equipment:

4 x 68 watt 12 volt Solar panels
1 x Sunlight controller
2 x 6 volt 375 Ah Batteries
7 x 12 volt 13 watt Fluorescent Lights

The sunlight solar lighting controller connects the solar panels, batteries and light fittings.

The controller uses the solar panels to charge the standby battery pack and also detects sunrise and sunset to determine when the light fittings are to be switched on and off. Tansley Electrical offers a comprehensive design and build service to accommodate all solar power installations from stand
alone packages to grid connection options. It is also committed to working towards a future where we can all live in a healthy and sustainable environment.

Calder Stewart Solar Rib®