Trial by fire are you ready?
Fire is the hot topic of conversation as the Nelson blaze continues to burn and other fires break out. What can you do to be prepared?
The sprawling forest fires in Nelson have brought home the dangers homeowners face. A feature of the massive Pigeon Valley blaze and the smaller fire that threatened homes on Walters Bluff in Nelson city, was the speed at which they spread in the tinderdry conditions.
With such conditions expected to become a more regular feature of New Zealand summers, the fires are a timely reminder of the need to be prepared.
Remarkably only one house has been destroyed in the 2300-hectare main forest fire, but the toll could have easily been worse.
Dozens of other houses came perilously close to being burned.
With no sign of significant rain, fire risks in Nelson and throughout the country are expected to remain very high for the foreseeable future. Houses in rural areas, or near forest, bush or grasslands are at the greatest risk of wildfire, with 37 houses and other structures destroyed by wildfire between 2014 and 2018.
So what are the major risks associated with outdoor fires; and how should homeowners go about preparing for a worst-case scenario?
To get an insight on how to prepare, I talked to one of the coordinators of the firefighting effort in Tasman, Principal Rural Fire Officer Ian Reade.
When wildfires start, it isn’t the flames from the main blaze which are the biggest danger. By far the biggest cause of house fires was from embers blown from the fire.
Carried by the wind, embers can travel kilometres from a large fire and land on or near a house – where they can ignite flammable material.
While a house will be able to withstand immense heat from a close distance, a few sparks in the right place can start a fire.
Reade said during the height of the Pigeon Valley fire, embers were being thrown up to 500m ahead of the main blaze itself.
‘‘It’s not uncommon in Australia for houses to burn down kilometres away from a fire, and the same in the USA.
‘‘You’ll have embers come and land in the gutters or spouting on the roof, get into the leaves, go up into the building paper and roof cavity – and when it takes hold then you can’t stop it.’’
Embers tend to gather where leaves gather, often in guttering or the corner of a deck or fence.
When they dry out, leaves can be a major hazard in the event of a fire. Other vulnerable areas include: areas underneath a house where flammable material is stored; hessian door mats; open windows, doors or vents; underneath decks; outdoor furniture covers.
When the Walters Bluff fire on the north-eastern fringe of Nelson city flared up a week ago, Reade said firefighters instructed residents to put their deck furniture inside, hose down the roof and fill gutters, dampen down decks and remove any loose leaves.
Blocking off down pipes with tennis balls also provided a stopgap solution to prevent embers swirling through the pipes.
‘‘There’s quite a bit you can do before you leave your home if a fire is coming through.’’
Along with the danger from embers, there still is a risk to property either through a ground fire reaching the house or from excessive radiant heat.
Typically ground fires will reach a house when they have an uninterrupted supply of fuel up to a property – burning through low vegetation such as dry grass.
Attachments to a house, such as fences, decks, garden edging or trellis, can also provide an access point for a ground fire.
Creating a 10-metre safety zone around the house free of materials that could ignite a fire can also reduce risk from ground fires.
The advice is to remove all firewood, trees, long grass, shrubs and branches, twigs and needles within 10 meters of your house, as they are fuel for fire.
Reade said with ground fires, high winds and steep slopes could make a fire spread much more quickly. ‘‘The rule of thumb we have is for every 10 degrees of slope, you will have the fire go twice as fast as it does on the flat.
‘‘With 20 degrees of slope, that’s four times faster than on the ground – and if you have wind behind it will go even faster.
‘‘In the Pigeon Valley, when you combine the slope of the hill and the wind where it started, it sent it off like a rocket.’’
The Walters Bluff fire started in similar conditions, but helicopter crews were alerted almost immediately and got to the scene quickly. In total, that fire covered just under three hectares and was brought under control after several hours.
‘‘It comes down to early detection, there we had four helicopters onto that within minutes. Had that been left 20 more minutes, that would have been a much bigger fire.’’
Another approach to protecting property is through fire safe landscaping (or ‘‘firescaping’’).
Reade said the recent fires had shown first-hand the effective of planning your backyard for fire prevention.
‘‘Some people have actually put some thought into it and landscaped to have low flammable species around the house – I’d suggest there’s houses out there that have been saved by that.
‘‘Some of it was because people had done good landscaping, some was the efforts of the guys on the ground.’’
Redwood Valley resident Guy Mollett designed his garden after attending a demonstration by the Appleby Rural Fire Brigade a couple of years ago on how to protect a property from fire.
As a result he had planted flax along the exposed side of his property to act as a fire break.
Along with the work done by the firefighters, no structural damage was done to the house despite the fire reaching within just metres.
When firescaping, the key factors to consider are to use nonflammable materials and fireresistant plants where possible.
Keeping the area tidy is also crucial, such as regularly mowing lawns, removing debris like twigs and pine needles, and pruning.
When planting trees nearby, use fire-resistant plants with moist, supple leaves and low levels of sap and resin – deciduous trees such as poplar, birch, maple and willow are generally fire-resistant.
Flammable plants to avoid, such as pine, eucalyptus, manuka and ka¯ nuka, often have fine leaves, loose bark and have a gummy, resinous sap.
Reade said plants from parts of the world where forest fires were common, were often the most dangerous. ‘‘[In Australia and North America] the ecology of the forests rely on fire to reproduce.
‘‘With eucalyptus trees they’ll send up firebrands 10,000 feet in the air, they’ll travel kilometres and land as big as your finger.
‘‘New Zealand doesn’t need fire in its ecology to reproduce, whereas in Australia it does – the native vegetation we’ve got is needles and finer stuff, it doesn’t go as far.’’
For houses close to rural areas, steep slopes covered in scrub were also a major fire risk.
‘‘Scrub is the highest burning vegetation type – things like gorse, broom, manuka/kanuka.
‘‘Because it dries out real quick, we’ll get extreme fire activity from gorse in winter after it dries out for a few days with fine weather.
‘‘Nelson has a lot of properties on hillsides with gorse or manuka and kanuka – people need to be prepared.’’
Long battle ahead
While the immediate danger from the Pigeon Valley fire has eased, the fight to contain it will continue for months to come.
Most of the action is now underground, in the root systems of the trees burnt in the initial wave of the fire. ‘‘In the Port Hills fire we were digging down metres to get to the hot spots ... If you’re talking about a fire that’s gone into a forest, it will go deep down into the roots and can pop up months later, potentially.
"Once you get winter rains and cold conditions that can put it out. With Pigeon Valley, it will be until we have 75ml or more of good rain, we’ll be watching it until that happens.’’
With the fire danger in Tasman and around the country remaining high, Reade said communities needed to play their part to help prevent any more fires taking hold.
With plants drying out during the heat, anything that creates sparks can be a potential risk.
‘‘We can’t police everything, we rely on people to own that risk.
‘‘We need our communities to work with us to manage it – if people see someone doing stuff that can lead to a fire, they need to say something.’’
Some people have actually put some thought into it and landscaped to have low flammable species around the house – I’d suggest there’s houses out there that have been saved by that. Ian Reade