Saturday, 17 December 2016

Up on the roof! [learnings]

Hi everyone,

Sorry I've been away a few days.  I've been persistently tired in the evenings and that makes it hard to write.

It was a busy couple of days in emergency-service-land this week.  A narrow but fairly powerful squall lashed across the Goulburn Valley on Tuesday, roughly from Lancaster to Tamleugh.  I spoke to one of the Powercor crews and I know it cut power lines at Toolamba and Karramomus.  For my SES unit it generated a run of tree-down-traffic-hazard and roof jobs that lasted until a bit after 0100 the next day.  It also did some roof damage that wasn't detected by the home owner until Wednesday afternoon.  What made this job striking was that the damage occurred on a second story roof.

Two story houses aren't unheard of in this area, but they're also not common.  Certainly this was the first that I'd been called to work on.  I learned a couple of things on this job that might be of value to other emergency responders, so I'm sharing them here.

The first is to think about any extra safety you might need in your setup.  Because the safety rope for the roof crew was going over such a high roof, the line was particularly long.  This meant there was extra opportunity for the rope to flex and stretch in a way that might endanger the roof crew.  To counter this a second bracing line was put on the side of the roof that the crew was working on at about a 45-degree angle.  The bracing line was anchored at ground level; on the roof it was joined to an alpine-butterfly knot in the safety line with a carabiner connecting to a figure-of-eight-on-the-bight knot.  I think the choice of this latter knot was just a matter of personal preference by the other crewmember: for myself I'd have used a bowline which I find quicker to tie and less prone to jam.

The second is to think about how you'll get up there.  We used one ladder to climb up onto a balcony, and then lifted up a second balcony to climb onto the roof.  The owner warned us, however, that the balcony floor was in less than A1 condition: it would take the weight of a person spread over the area of their foot, but the footings of a latter might punch through it.  We took up an inch-thick square of moulded plastic (part of our rescue gear) to put the ladder's feet on.

I was footing (steadying) the ladder from the balcony to the roof.  The other roof crew member felt there was too much risk of the ladder overbalancing when he was at the top.  We counteracted this by bringing up a third crewmember to steady the ladder along with me.  So lesson three: if you need more hands to make it safe, ask for them!

Once on the roof, I ran into trouble transferring from one side of the ridgeline to another.  Part of the difficulty was that the alpine butterfly knot on the ridgeline was close to the knot for the bracing line.  This isn't really a problem worth unpacking: SES is doing away with this particular aspect of the rooftop system.  However, I did notice one thing: the safety rope was particularly hard to handle.  That is, its own weight dangling over a long distance was pulling it taut.  This is another matter for a roof crew to keep in mind.

The repair on the roof was actually fairly straightforward.  All we needed to do was replace some tiles and lower a rope so that a spare tile and some silicon could be sent up to replace a breakage.  I'm afraid I don't have any particular learnings from this one!

What learnings do you have from recent incidents?

No comments:

Post a Comment