Back to slating

Slating around the first rooflight 
We reached the first of our 15 rooflights, so we dug out one of our flashing kits, sat through a couple of YouTube clips and tried to make sense of the instruction leaflet. We had to cut slates to run them about 20 mm below the frame. This was going to be out of sight so I used the small angle grinder with a diamond blade. The bottom part of the flashing lapped over the slates and part way up the side of the frame to work as a soaker for the next course. We used the slate guillotine to trim the next five courses to size, fitting the soakers as we worked upwards. Our slates are quite chunky, so the top edge of the soakers were a bit above the top of the frame, we used the aero snips to trim the tops back. Next up we slid the covers up each side over the soakers onto the frame, screwed them down and fitted the top part of the flashing up against the top of the frame. That screwed in place and we cut the two courses of slate above the rooflight to lap onto the top flashing, 60mm or so from the frame. And that was it. It was slow but not difficult despite the instructions. 

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Flashing the coping stones 
We started this section of roof against one of the gable ends with a raised parapet and coping stones. We had already cut a groove 30mm from the top of the stones, around 6mm wide and 25mm deep. Our rolls of code 3 lead were 240mm wide, enough to cut down the middle. We cut a 1.5m length, scored a line along with a Stanley knife, folded it back a few times and it split into two 120mm strips quite neatly. We lay the first strip over the edge of the workbench and used a rubber mallet to gently fold one long edge over on itself by 5mm. We cut away the end 75mm of the fold so there would be room to lap the next length of flashing into the groove in the coping. Then a second fold 25mm in, the other way down, leaving a skirt about 80mm deep. The lead was surprisingly soft and floppy, so needed carrying with both hands. We made up three lengths, more than enough to run from the base of the roof up to just short of the top. When we do the other side of the roof, we will finish the top courses on both sides, run a length of flashing right over the ridge and fit the ridge tiles over it. Back on the scaffolding, we gently tapped the 25mm lip on the first length into the groove in the coping and used a bolster to knock the folded edge against the back, raising it enough to lock it into place. We had trimmed the bottom end to 42 degrees, to fit against the top of the wall extension that is a feature of this corner of the east wing. To finish the job, we mixed a bucket of stiff dry mortar and pushed it into the groove to hold the flashing in place. 

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The rest of the roof
We made rapid progress once we were able to get a couple of full days in. We have moved two bays of scaffolding along, with less than two more to go. We have got the second, large, rooflight half-done after which it is simple slating right up to the north gable-end.

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Starting with the slating

Ric has started us working on slating. We will cover the east side of the east wing roof, since this runs between copings at each end, with no valleys.

As with most things in life, there is a lot of preparation. There has been the weeks of work sorting the slates into weight categories. Ric worked out the spacings we needed between courses, including the two starter rows that are hidden below the first visible course. The slates are around 465mm long and 230mm wide, we will have a headlap of 190mm and the bottom two courses will be ?? and ??mm long respectively. We made up a suitably large set square, attaching batten to our aluminium square. We used this to mark a vertical line up close to the coping, to find out where the coping was furthest from the line. This is where a whole width slate would be used, all others above/below would need trimming to size. The bottom-most slates needed special treatment because that is where the coping runs down onto the extension walling rather than a simple retaining stone. Ric cut a right-angled notch out of the first and third slates.

We agreed that the first five courses would use the heavy, thicker slates, then mediums for most of the roof, then a couple of courses of the light ones. The lowest course is nailed on upside down, with the second course right way up and lined up with the bottom of the first, 50mm beyond the edge of the eaves tray. The third, full length course also lined up with the bottom edge and it was then the 190mm intervals upwards with full-sized slates. We cut slates for the start of each row, to fit the space and avoiding having less than 150mm width. Cue the slate & halves that we got from the Slate Centre. The slate cutter was pretty good, though Ric reckoned it was not as good as his smaller one. I was able to cut the length of the slate & halves in two goes and across in one. We used the Hambleside Danelaw plastic soakers up against the parapet, just hidden under each slate and fixed to the sarking with a single nail. They did partly cover the slot for the flashing in the coping, Ric suggested we use the angle grinder to cut them out of the way before we fit the flashing. Where the nail holes were either too high up the slates or too low so that they were over the previous course, we found we could drill holes easily using the drill driver with a 4mm masonry bit.

I struggled early on with vertical alignment of the slates, getting successive courses exactly half a slate on from the row below. I had marked lines at 190mm across the bit of roof I was working on, I will also put vertical lines at intervals to check on the alignment. The other problem I had was that the bottom row had spacing between slates, but it ended up being squeezed out on the courses above. By the end of the first day, I had seven visible courses with the bottom row being 10 slates long. This will just about let me get up to the ridge, although we will leave the topmost ones to do from the other side, so we do not need to rest the roof ladder directly on slates. Collectively the slates looked good, even if they are a bit rough in detail (they are).

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Our slate&halfs have arrived

Our large (24” x 14”) slates have arrived – Ellon Timber delivered our crate of 400+ reclaimed welsh grey slates, they were as good as the sample suggested: Even thickness; good condition, good match for our existing slates. They are indeed as wide as one & a half of our slates, so will serve their purpose perfectly.

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Slate & Halfs

We reclaimed the slates off our old roof, but want to use slate & halfs (375mm wide rather than 250mm) rather than half slates, to make it easier to get a watertight roof, particularly up the valleys. I found a really good match last year with new Chinese Blue Grey Fesco slates from a store in Scarborough. So I phoned them up to ask about ordering 400 slate & halfs and was surprised that they were rude and grumpy and said no. I phoned several other places and one of them explained the problem – slates are shipped in consignments with lots of slates and not many slate & halfs, so if they were to sell me 400 of them, they would leave customers for their  slates short. I see their problem, but they were still abominably rude. And it opened my eyes to the fact that selling slates requires no knowledge, understanding about, or even control over, what they are selling.

Ric had the bright idea of looking for large reclaimed slates. The largest common size is 24” x 14”, which is not much narrower than the slate & halfs that we need. We found several places, mostly in Wales. The first did not have any, despite their website saying they had 10,000 of them. The second did, but refused to send me a sample. They said the slate would not survive posting, I said in that case send me a broken piece, they still would not. The third place did not answer the phone. The fourth said they might have a few hundred and did agree to send a sample out. After a week I phoned back and got a different person, who said they would send a sample out. A week later I phoned back and the original chap was there. He again said he would post a sample out and a few days later got emails saying a) he would, then b) he had, but the packaging looked suspect and he was worried it might fall apart in the post. A week later I was about to ring again when lo & behold, it arrived. It was in a Jiffy bag and somehow, they had got the sample pushed into the lining layer between the outside & inside of the bag.

What mattered was that it was an excellent match and when I said I wanted 400 of them, he went off to count them. He phoned to say they had 900 of them. Furthermore he thought he might get 400-450 of them onto a single crate, to reduce the delivery cost. If it all pans out, this overcomes the biggest obstacle to medium-term progress. It would have been great if it had happened a month ago, but better now than another month down the line. I expect it will put the squeeze on us in late summer to get the steading slated up. We recently acquired a large slate guillotine which will allow us to trim these slates down to the height of ours, as well as to cut the angles needed for the valleys and to fit the ends of runs of slate.

Unroofing – the start

I had worried that removing the roof would seem like a huge step back, leaving us with just the rubble walls and a load of stuff to dispose of. On the other hand, I  expected the roof timbers and sarking board to supply us with firewood for a year or two.

When it came to it, it is stopping us working on the stonework, so it has to go. Before Easter we bought our scaffolding and, the day we got on site, set up two bays of it against the inside wall of the west leg i.e. against the gable-end that must be demolished and re-built.

We had discussed about saving the slates and re-using them. The architect was very discouraging, saying they would be poor quality and that we would probably only save a low proportion, possibly enough to re-roof the bothy.

I armed myself with a slaters rip, claw hammer and roof ladder, then got going.

Ridge Tiles: Firstly the clay ridge tiles. From the ground they looked pretty bad and I expected that hacking them out would probably destroy them. Not so, they were in excellent condition, the lime mortar had crumbled and they slid off with little effort on my part. They were all marked with ‘Hurlford by Kilmarnock’. This probably means they were made by J & R Howie of Hurlford, Kilmarnock. I have no idea how old they are, we supposed they must date from the fire that damaged the steading either before or after WWII (depending on whose version you believe). It looks as though the same tiles were used along the entire roofline. http://www.scottishbrickhistory.co.uk/j-r-howie-scotland-kilmarnock/

Clout nails:I discovered very early on that the slates were nailed with standard galvanised clout nails. It was obvious that the rip would not work as advertised – if I hit it hard enough to draw the nail it would a) destroy the rip and b) destroy the slate.

Removing the slates: The course of half-size slates at the top of the roof were single-nailed in the top-centre. Most pulled out easily, indeed several on the other side of the roof fell as I moved the roof ladder about. From then on, it became harder work.

Most of the full-size slates were nailed both sides, a few cm down from the top. The nails were generally knocked flush with the top surface of the slate, but were enough proud in many cases to use a pair of pliers to grab the head, right at the very end of the pliers, then twist and pull the nail to remove it. Those that this did not work with, I used the rip to push under the slate as near the nail as possible, then used the claw of the hammer under that to lever the slate up. In most cases the slate pushed the nail up enough to then pull it with the pliers, without cracking the slate. It looked as though about 4 out of 5 slates survived my treatment AND were in good enough condition to re-use.

The half-length slates at the bottom of the roof were, on the whole, pretty rubbish and just used to cover the edges of the slates above.

We used our chain hoist to get crates of 15 or so slates down at a time, Jill sorted and stacked them.

The slates: The slates were generally smooth underneath, pretty flat and with no signs of imperfections such as pyrite (which oxidises, expands and breaks up the slate). They had a reasonably good ‘ring’ to them and were rather rustic. Comparing them to the ones off the old East Byreleask farmhouse (dumped out of the way on Aitken’s land) they are 1) larger, 2) thicker, with quite a bit of variation and 3) with a coarser upper surface finish. I actually prefer our slates. We left three slates, in varying degrees of preservation, with Jill’s parents. They should have a slater around to work on their roof and they will ask him whether they are fit to use again. I think the slates at the top of the roof were, on average, thinner than the ones at the gutter.

[Updated 17/04/2015: The slater said they were good quality Welsh slate and were good to re-use. If we wanted, say, Spanish slate, he would buy the old slates and we would probably profit from it. This brings to mind what may be an Urban (Rural) Myth that I heard twice in quick succession – that a slater would persuade the owner of a roof to remove them, saying they were not fit to re-use. They would offer to dispose of the old slate, which they indeed sold on, making a double profit over just fitting new slates.]

It is slow!: It is unbelievably slow – after four part-days we had cleared some 4% or the total roof area. I got a bit quicker, but not much.

The Skylights: There are a couple of dozen of these monsters dotted around the roof. They are made of cast iron, with the opening part hinged at the top and with a glazing bar down the middle. They are chunky, with little room for glass. They came away much more easily that I had feared. I used a prybar to lever the nails out – one each side halfway up and two at the top, just about on the corners. There was a strip of galvanised mild steel under the lower edge, but no additional strengthening in the timberwork. Each one weighed a good 30 kg.

The Roof Timbers: It was obvious the sarking board was in a bad state. They were worm-eaten and often the nails would pull out easily. Once I had cleared the slates above the scaffolding, I removed the boards and was horrified at what had been holding me up (on the roofing ladder). Most broke apart in clouds of dust, only a small number of boards still had any flex in them. It was a quick job to remove them, but they are not really usable as firewood – we will have a bonfire at some point.

By removing the boarding, I came to realise that there was no beam along the top of the roof – once the boarding on the other side of the roof is removed, there is nothing to stop each pair of rafters simply falling sideways – I will take advice on this.

Meanwhile we need to think out how to speed up the un-roofing – we are even thinking about unpaid leave from work.