It was quite windy yesterday (Thursday) so I went up to the site briefly this afternoon to see how the tarpaulins had got on. Mostly OK.
The wind gusts not far away got to 45 knots (23.1 m/s, 83 km/h, 51.8 mph) so I wouldn't have been too surprised if there had been quite a bit of damage. Here's the “gustiest” METAR of relevance:
EGPC 211250Z 33030G45KT 9000 -RA BKN014 BKN026 04/02 Q0965
(Wick Airport (ICAO locator EGPC), on the 21st at 12:50 UTC, wind from 330° (NW) at 30 knots gusting to 45 knots, visibility 9000 metres, (recent?) rain, broken clouds at 1400 and 2600 feet, temperature 4°C, dewpoint 2°C, sea-level pressure 965 hPa (mb).)
In particular, I rather expected the first proof-of-concept tarpaulin, which already had some tears, to be shredded but actually it was mostly as it was before:
Though the top left corner had pulled out from under the batten and come to bits somewhat:
Just over the ridge on the south side the end of the top batten had also pulled out:
IIRC, I used 51 mm ring nails for that. For the later sheets I used screws to be able to get them out more easily and probably causing less damage to the horizontal battens.
It was a bit too windy and slippery underfoot with sleet showers around so I didn't feel up to trying to do a repair today. There should be better weather over the weekend or Monday for that before there's any more high wind.
DJH asked about how the battens were clamping the tarps where they join. Hopefully these pictures will make it clear, the east tarp (this is on the south side so the one on the right) is fully clamped only where the first batten up and down the slope crosses the horizontal batten. The west tarp is then clamped over the whole length of the two battens.
I've since started improving on that a little by wrapping the east tarp round the batten and stapling it on top so it too is clamped over the full height once the second batten is added. Here's the east end of the last tarp I put up (on the north roof) waiting for the edge of the last tarp to be clamped over the top of it.
It's not always practical to do that over the full length. See, for example, the top of this batten.
