In the first of a series of articles, Wellington City Council’s Manager of Major Projects and CBD Building Consents and Licensing Services, Robert Tierney, offers advice and explains the process of gaining consent for alternative solution proposals.

What is an alternative solution?

There are two ways of demonstrating compliance with the building code, which is a performance-based requirement for building work.

1. An acceptable solution comes from a suite of documents issued by the Department of Building and Housing (DBH) called compliance documents. If you follow the prescribed method in those documents it is deemed to comply. If you build with those details the building consent officer or council or local authority will accept it because they know it’ has been issued by the DBH and it is deemed to comply.

2. Everything else is an alternative solution. An example I often give is that if you to build a 20-story building out of recycled coke bottles, then that’s fine but then the onus is on you to demonstrate how you are going to make it stand up, how you are going to stop it from leaking and how it is going to perform adequately for the purpose required and for people to live in it.

Window framing is one example of where this situation occurs and alternative solution consent is required. Why is that?

A compliance document is available for window framing as a result of the issues around weather tightness. The compliance document is called E2 AS1 and it shows acceptable solutions for doing cladding with particular materials, which could be timber weatherboards, board and batten as well as profiled metal in stucco systems. This document, however, only has generic details for window frames. It doesn’t provide specific details for different types of frames, for example metal, wooden, plastic or whatever. So theoretically an alternative solution is required for window frames because these details are not mentioned in the compliance document.

So how do you go about the consent process?

There is, however, another way of viewing consents for timber window framing and this is to refer to its in-service history. People have been using timber windows and doors for centuries so it has an in-service history. But this way of getting compliance is not very well-utilised.

How do we know that in-service history works?

The simple answer is look around you, there are hundreds and thousands of buildings around Wellington that were built that way. It works; it’s proven itself so its in-service history is a very valuable means of demonstrating compliance with the Building Code.

How do you use in-service history when making a building consent application?

Basically an architect or designer can reason that what they are proposing in a drawing will work. They can argue that what they are proposing has been proven in its in-service history. A lot of timber windows very much fall into this consent category and it should be acceptable. People still need to detail their applications correctly for insulation and flashings and things like that. Theoretically there isn’t a problem with such consents for timber window frames that are made correctly in accordance with the standard profiles for their use, and as long as they are installed correctly with the right flashings. Obviously the choice of materials that is used is important and that’s something that comes down to durability. There is a particular standard for this, the NZS3602 compliance document.

What happens with a compliance document?

The compliance document will say thou shalt do it in this particular prescribed method. And what they will often do is reference a joint New Zealand Australia standard. If you follow that standard it is deemed to comply. So this is the case in terms of timber durability and the choice of the right materials for a particular job, obviously you can’t use balsa wood for a timber door or frame. That standard clearly references what timbers are acceptable for particular durability uses. And that’s all you really need to consider.

Other news featured in this week’s issue includes just how large the projected demand for lumber in China is. For Kiwi forestry companies, we knew it was big – as evidenced by record log volumes that have gone across the country’s wharves this year. However, just how big and how prolonged this demand is likely to be is surprising. China’s lumber imports almost doubled between 2000 and 2007. According to International Wood Markets Group they’re expected to double again in the period 2007 to 2010 and then show a 70% rise or a 12% increase in annual growth from 2009 through to 2015.

NZFOA

3 September 2010

Forest Owners response to Hon Dr Nick Smith’s Announcement

The forest industry strongly supports the proposed national environmental standard for forestry released today by environment minister Hon Dr Nick Smith.

“For the first time, land owners will know before they plant a single tree what harvesting and earthworks standards they have to meet,” says Forest Owners Association president Peter Berg.

“Owners of existing forests will draw comfort from knowing they will be able to actually harvest the forests they may have planted decades ago. Sure, they will have to meet strict standards for roading and harvesting – but the rules will be consistent wherever they operate, and well attuned to the regional geology, climate and land use capability.

“The FOA supports robust standards based on science, good forest planning and good engineering practice, applied consistently throughout the country. In some regions this means forest owners will have to meet tougher conditions than they do now. But that’s a reasonable price to pay for investor certainty.”

At present, rules vary from region to region and between districts within many regions. In many cases land owners have to apply to both regional and district councils for costly and time-consuming resource consents for normal forest operations.

“This can be extremely frustrating for farmers who have forests divided by a district council boundary. They may have to apply for two harvest consents, with all the attendant legal costs,” says John Dermer, president of the Farm Forestry Association.

“If the NES becomes law, farm foresters may not have to pay for a consent at all so long as  they meet permitted activity standards. Or, if the land is erosion-prone, the consent conditions are likely to be the same on both sides of the boundary. This will be a big step forward.”

Mr Berg says getting consents can be hugely costly. He points to the $1 million it cost the owner of a 10,000 ha forest on the Coromandel Peninsula to secure and defend his operating consents and the $100,000-plus a year he shells out for compliance.

“These sorts of costs have become significant barriers to new planting by commercial forest owners. Hopefully Dr Smith’s announcement will lead to the adoption of a national approach for managing forestry that in turn will encourage the new planting needed if New Zealand is to meet its 2020 emission reduction targets.”

FOA environment committee chair Peter Weir notes that point-source discharges of sediment to waterways from earthworks and quarries within forests remain illegal.  He also says the proposed standard will see councils continue to regulate earthworks in terrain that’s susceptable to erosion.

“We have no problems with that. Some very fragile soils are not suitable for commercial forestry and councils have a responsibility to ensure they are managed appropriately. One of the big positives of the proposed standard is that councils will be flagging this before trees are planted – not after a land owner has made a substantial investment.”

Mr Weir says forestry investors should look long and hard at the afforestation provisions before they buy land, while existing forest owners should focus on the reforestation terms and conditions.

“All land owners should look at the land use classification mapping for their land. On easier country, the NES as proposed makes most operations within a plantation forest a permitted activity, but subject to a suite of defensible terms and conditions. On steeper more erosion-prone country, resource consents for road and landing construction will continue to be required.”

[ends]

Speakers included visiting wood-specialist engineers Richard Harris (see other news feed) and Stefan Winter (pictured) from Germany.

Stefan, who started his career as a carpenter, now spends his time between professorial roles in Munich and Helsinki universities. Sustainable constructions are the main focus his scientific and practical work, with one of the themes of his presentation being that buildings are complex systems.

He is also an advocate for reducing construction time on site through the use of efficient pre-fabrication. He gave an example of an ocean liner that provided living space for 3,500 people “a village” being able to be built in 11 months in a sophisticated manufacturing/construction operation. “Why can’t we build a village for 3,500 in 11 months?” he asks.

Harris, who is Professor of Timber Engineering at the University of Bath, is based at Canterbury University for two months, where he is working with Professor of Civil and Natural Resources Engineering, Andy Buchanan. Harris is lecturing to the university’s undergraduate timber engineering students and presenting talks around New Zealand.

He says he is excited by the ground-breaking research Andy Buchanan is conducting on pre-stressed timber technology for the Structural Timber Innovation Company (STIC). The technology was used in a multi-storey building for the first time on the Nelson Marlborough Institute of Technology’s new Arts and Media building, opening next year.

“I have seen some timber framed office buildings, there is one in Helsinki, but they are not common.” He says STIC’s research on developing seismic resistance in pre-stressed timber is the first of its kind in the world. “Clearly the seismic resistance and the robustness that provides is very innovative,” he says.

Richard Harris’s research interests lie in tall timber building structures. He says STIC’s research is much further progressed than research into tall building timber structures in the United Kingdom.

While in New Zealand, Richard is also presenting at the Timber Design Society’s Wood Solutions seminars.

Previously Harris was Technical Director with Buro Happold Consulting Engineers. He won the top UK award for timber structures, the UK Wood Awards Gold Award, three times in four years.

Visit the Forest Industry News website to read more.