May 2012 – Geoff's Blog

So, after weeks when not much appeared to change, suddenly there are big, obvious developments.

The work on the retaining walls and paving has moved on substantially now, and it’s pretty much off the critical path. There is still (a lot) more to do, but the shape of the paving and steps all round the house is clear, and we are on track to complete the wall that will retain the bank to the right of the house. That will be a great relief, as it will mean that both Alf Blackman’s drive, and the sewer pipe beneath it, will be properly secure.

But today’s particular fun was the lifting into place of some of the big structural timbers for the roof.

Josh was out in his BYT again, a huge JCB forklift, with an enormous reach

Clearly serious stuff, as Josh had to turn his hat round!

The most impressive job was lifting the ridge beam for the roof above the master bedroom into place. This is a 420×140 glulam beam, that located in a pair of sockets at the gable and at the junction with the main roof

The fork lift lifted it about 10m above the ground, and 6 or 7m over, and dropped it directly into place. Well, it was 8mm out, but I suppose that’s OK in the circumstances. Jamie seemed particularly impressed!

The remainder of the work was lifting some more huge timbers into place for the main roof

Tricky, mainly because access is a bit limited. But the forklift was truly impressive

April was an extremely frustrating month. After the rapid progress we made at the end of March, things pretty much came to a halt at Easter. Josh and his team finished the work they could do on the timber frame without scaffolding in place. The scaffolding, in turn, depended on completing the retaining wall to support paving across the front of the house. Then the weather intervened again.

The news in April was full of declarations of drought, hosepipe bans and dire predictions of standpipes in the streets. “Worst drought since 1976!”. Then the rain started. And it rained. And it rained. Then it rained some more. On the radio, someone said that it had been “Droughting heavily in Cardiff”. Whilst the site was not as badly flooded as in January, Darren, one of the groundworkers, lost his bet about the depth of the water in the Void, when it overflowed the top of his wellies. Then it rained some more. So progress on the retaining walls was painfully slow.

Bore Holes

20120403Holsworthy Groundworks0006 — Drilling Rig

At the same time, the bore-hole drillers finally arrived, after a few false starts, to drill our 210m of borehole for the ground-source heat pump. There were supposed to be three holes, each 70m deep. Our information was that the house sits on Bude Formation sandstone; we had expected, therefore, that the boreholes would be fairly straightforward. In the event, things were not quite so simple.

The drillers set about the first hole, and quickly hit the water table at 7m down. That meant a cascade of water out of the hole, propelled by the compressed air used to drive the drill hammer. So another river down the site – fortunately, flowing away down into the River Deer. Then, rather than the uniform sandstone we had expected, they found the rock fractured and containing loads of hard inclusions, which made the drilling difficult. Eventually, they managed to get that hole down to 53m – some way short of the planned 70m, but usable nonetheless. The next day, a second hole. Most of the same problems, but eventually, the hole went to 79m; better we thought. But then the next problem. The drillers had had to insert a temporary steel casing in the top 20m or so of the hole, to prevent it collapsing. Normally, they would withdraw the casing with the drilling rig. When I arrived on site, the drillers were sitting in their Land Rover, wondering how to extract the stuck casing. Shades of “Need a bigger hammer!”. The legs of the drilling rig were bent, the casing stuck firm. Phone calls to the boss, and general despondency.

A day or two later, we returned to see a pair of HUGE hydraulic jacks around the top of the hole. They could evidently exert 30Tonnes force, and managed to extract the rogue casing. So, we now had 132m of bore hole. All we needed was another 77m, and all would be well.

We went to site on the day they had started drilling the third hole. The rain was coming down in torrents, the wind blowing. A perfect spring day in Devon, then. “How’s it going then?”. “Not well. Down to 30m, and hitting real problems”. We stood inside the house, out of the pouring rain, and watched the driller, standing in the rain, with a torrent of water coming up out of the hole, and the drill turning, catching, having to be withdrawn and tried again. This was not going to plan at all, and we wondered what Plan B could be, particularly when the poor chap threw his hands up in resignation and retreated to his Land Rover.

The conversation before we left amounted to “Not going well, do the best you can, see how things go”. We didn’t expect much, to be honest. When we returned the next day though, the news was good. The drillers had stopped for their lunch break, then gone back to work on the hole. They had struggled for 15 minutes more, then the drill had found easier rock. The hole was now down to 79m, and we were OK, provided the pipe loop would go down smoothly. It evidently did, and we now have three pipe loops sticking out of the tops of the boreholes awaiting terminations.

More Groundworks

The critical path for the build was now the completion of the retaining structure to support the path in front of the house. This is needed to support scaffolding to complete the upper floors, and to support the porch structure on the house. The speed of progress here has been frustratingly slow, and the work is still not complete. The weather has not helped, certainly, but there are some other factors too.

In the interests of getting things moving, then, Sean (project manager) suggested that we erect the scaffolding around the rest of the house. Josh is happy to work off that to put the roof on the frame – about 2 weeks’ work – which has to be enough to get the paving in place.

So, yesterday (Friday) the scaffolders arrived…