North Roof

An Eccentric Anomaly: Ed Davies's Blog

As previously mentioned I've been interleaving work on the north and south roofs, mostly as the wind indicated. I don't seem to have many pictures for the north roof but here's a quick summary anyway.

At the end of August I was pretty much stuck on the north roof as I needed more battens to go up the edge before adding the firestop and DPC which the last sheet on the bottom row would overlap. Similarly, because of the way the sheets are overlapped I couldn't do the last two sheets on the middle row or the last three on the top row. Those battens arrived with the sheets for the south roof on Friday September 3rd but what with my back problems and working on the south roof I didn't do them till Saturday September 18th.

The bottom right sheet for the north roof was damaged by the wind at the end of September.

On Sunday, October 24th the north roof was still as it had been after I put the battens up (except for the damaged sheet). I put up the fibreglass mesh sealing the tops of the gable boards in the top part of the roof (above the porch/greenhouse) and the firestop and DPC. Here with the firestop in place and the DPC about to go up:

I replaced the sheet bent by the wind (R1) on Tuesday, November 2nd then put up the sheet to its right (S1) and the one above it (R2) on Thursday that week completing the middle row with sheet S2 on Thursday, November 11th. The last of those was quite awkward to do as R2 was a bit rushed and finished up a bit skew so S2 was difficult to line up with the verge neatly then, for some reason, it was initially a bit low and I needed to unscrew it and move it up about 25mm which was also awkward as I'd already removed the lifting rope and block when I realised.

Anyway, this is what the north roof looked like on November 15th, with the last three sheets in the top row (Q3, R3, S3) left to do:

On Sunday, November 14th I drilled sheet Q3. I also made a new lifting block to screw under the sheets being lifted. The old one is 6" long to go across two roof ridges whereas the new one is 12" long. This allows the rope to be closer to centred on the roof sheet which, on the couple of sheets I've done with it, makes lifting quite a bit simpler as the sheet doesn't get skew so much. However, it does mean I have to stretch across the sheet a bit further to unscrew the block before I've got many screws in holding the sheet fully. I put that sheet up the following day.

Sheet R3 was done on Friday of that week, November 19th.

I drilled the last sheet (S3) on the Tuesday 23rd but by the time I'd done that it was getting too gusty for me to try to put it up. The next few days were too wet and/or windy to contemplate putting things up, particularly Friday which was very wet and windy but I had a hospital appointment in Inverness anyway.

Sunday, November 24th was nicely calm but with a layer of snow lying so I arrived on site to this view of the north roof:

Waggling the ropes around caused a few more avalanches clearing the roof a bit. At first things went well and I got sheet S3 pulled up and ready to screw in place. I had a visit from another programmer who's contemplating building a timber-frame house on the north coast with similar foundations to mine, only taller on account of flood risk. We had a good chat for an hour or so.

With most sheets I've been putting in screws across the bottom and up the left side first then removing the lifting block (and for top-row sheets the pulley) by reaching under the sheet from the other side. Of course, with the last sheets at the gable end that's not really practical. For the ones below this one (S1 and S2) I've just put a few screws in the bottom then pulled the lifting block and ropes out from the left side before screwing that down, moving the ladder across and screwing the right hand side down.

This is where things began to go wrong. First I dropped the pulley under the sheet. The more I lifted the sheet up to reach down for it the more it slid down out of reach. I tried using a curved wrecking bar as a crook to grab it but couldn't get a hold on it but when that didn't work decided to just leave the pulley under the roof and get another one.

Then, when I came to put the screws in up the side I found that the top row of pilot holes were just below the top batten. I've yet to work out why. I was now stuck with the sheet held by just three screws at the bottom, no practical way to get the pulley back into place to lift, hold or lower it and not a lot of daylight left.

My first thought was to use a couple of bar clamps as spreaders between the top of the batten ramp I use for sliding the sheets up the roof and the bottom of the sheet to first take the weight of the sheet while I took the screws out then lift it a bit. Unfortunately, the clamps I have were just a bit short for that. The whole idea was a bit sketchy anyway and adding anything else as an extension didn't seem sensible.

So, I decided to abandon that sheet for the day and work out a way to lower it down. First I removed the screws, centre one last, so that the sheet slid down the roof to rest on the batten ramp. Then I screwed the lifting block back on to the sheet, this time from the top, with just one rope tied to it. I threw the rope over the ridge and tied it to one of the battens near the bottom of the south roof.

I then lifted the bottom of the sheet onto the ramp so it slid down a little way taking the tension in the rope. From the south side, working blind, I let out the rope slowly to lower the sheet down the ramp. After it'd gone about 2/3rds of the sheet length down one of the screws for the lifting block caught on the top of the ramp and it stopped. Accordingly, I wrapped the rope round the south roof batten a bit and climbed up to free off the sheet. I expected my wrapping to either tighten up enough to stop the sheet moving or at least pay through slowly enough that the sheet could be slid down controllably. Nope, it shot down, landed on the wrecking bar I'd dropped earlier and mangled the bottom edge. Should have tied it off properly.

Maybe I'll be able to use part of the sheet elsewhere, e.g. under a south roof window, but it's got a lot of pilot holes in it already so that might not be practical. So I managed to do the whole of the north roof without wasting any sheets then wrecked two (the one bent by the wind and this one) doing the last column. Looking on the bright side, at least I got my pulley out.

More interestingly, I'm not yet sure what happened with the positioning of the pilot holes in this sheet. I was working from the same batten spacing notes as the two sheets to its left so I'm not sure if I just got the measuring and drilling wrong or the battens wander enough in that short distance for it to matter. Generally, I've been measuring every three or four columns across the roof and only found variations of 5 to 10mm so shouldn't be completely missing a 50mm-wide batten.

That snow's been washed away by rain since but last night added another thin coat for today. In principle I could have gone to the site today to do some measurements and figure out what happened, though it would have been too breezy to try to put up a replacement sheet, but I slept badly and doubt I'd have had the patience for messing around like that in the cold. Hopefully, precipitation tonight will fall as rain and wash away this snow, rather than fall as snow and add to it and it'll be a bit nicer tomorrow to have a look.