Still Slating

We are still slating the roof, as the weather permits. We are solidly into Autumn, so it is cooler and the weather is wetter, but we have not lost many days so far. We would not want it to get much colder, so it is a bit of a race against time. We probably have another 8 days work left on the north-facing roof, plus the time we will ned to flash the solar panels on the south side and to fit the ridge tiles.

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We are working much more quickly now and have a good system going where one of us can pass slates up to the other one up until 9 courses from the top, then use the short roof ladder to get those upper courses done. It is much quicker to move the short ladders than one long one and so far we have not cracked any slates through resting ladders on slated roof.

We installed a second roof slate, this time for our stove flue-pipe. The latter will be 6” inside, 8” outside diameter, so we got one with a 219mm tube. It arrived well folded up and-battered looking, we got it straightened out and waited until we got the slates up to where we wanted the bottom of the lead slate to line up. We used the jigsaw to cut out the sarking to the diameter of the tube +75mm all round. So a comparatively enormous hole. Fitting the slate turned out to be simple because it lined up nicely and I was able to use full sized slates and slate-and-halves without any cutting. The top edge was just below the ridge so we fitted the top-most course of slates above, directly onto the lead. The ridge tiles will cover the top edge, all very simple and neat. The areas we have slated have been fully tested and we have not seen any leakage at all, so we have the whole east wing and chunks of the north wing properly weathertight. I also understand why we had so many leaks through the membrane – rain was ponding up above the battens we used to hold the membrane down, the water was running through nail holes to the sarking and wicking down the underside of the membrane. When the water got down to the rooflights, there was no membrane left and the water dripped off the sarking immediately above.

Preparing for PV panels

Our building warrant expects us to put a row of PV panels across our south-facing roof overlooking the courtyard. Now was the time to do something because we cannot finish the roof without the panels. We slated along the lower half of the roof, along the entire 23m+ length, taking in the five rooflights and getting the slates to the tops, so we could completely install the flashing kits. We worked right to the bottom corner of the west end of the roof and left the slates on the diagonal, to just cover the 5^th rooflight. We will probably nail OSB up over the edge of the slates over the winter, to preserve the breather membrane until we get the west wing roof on.

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We contacted 6 companies, some very local and others around Edinburgh, saying we wanted a 4kWp array with microinverters, mounted directly on the sarking boards/breather membrane. We explained that longer term, we wanted an integrated system with the ASHP, woodburner and thermal store.

Five responded. One, Install Solar from Livingston, were the first to visit us on site. The person was surprisingly helpful and appeared to live, breathe and eat solar panels. He persuaded us to go for as many panels as would fit, he thought 20 at 310Wp each – around 6kWp – because the panels are relatively cheap i.e half as much capacity again for around £1,000. He also suggested 4.7kWh-worth of batteries because it makes it easier to make full use of all the electricity generated. We would still divert unused electricity to heat water, but should be able to cover evening use of electricity – lighting etc.. He thought we did not need microinverters because the shading of panels at each end would be gradual and regular and should be covered by bypass diodes in the panels. These prevent a panel that is shaded from stopping the other panels from working fully. Finally he said that they did not do heat pumps etc., but thought it was a good plan. He suggested a phase-change thermal store rather than just hot water. It was a very useful visit and we even had in the back of our minds putting extra panels on the west wing, to get earlier morning and later evening sun. Two days later, Aberdeen Solar visited us. They suggested a set-up that was exactly what we asked for, but they seemed resistant to going from 16 to 20 panels. Novus Elements were interested in quoting but did not visit. They were flexible and were happy to quote for 20 panels. Two companies did respond but did not react in time. So we ended up with three sensible quotes. After only a day or two, we went for the Install Solar quote, including the batteries. They said they could install the system on the following Wednesday. It was all a bit cheaper than we were expecting, I expect the recent demise of FIT meant the industry is mostly below capacity.

Slating the roof valleys

We worked our way across the second half of the east wing roof until we got to the point where the north wing roof meets it – this was the first of our roof valleys. We dug out the GRP valley boards we acquired several months ago and got to work. We peeled back the roof membrane from both sides, revealing the strip of membrane we ran down the valley for 500mm each side, it was intact and in excellent condition. We nailed the outside edge of the valley to the sarking in four places each side above the strip of membrane, ran double-sided butyl tape all the way up each side on the outermost of the two small ridges, stuck the roof membrane to the tape and trimmed it back to the ridge, leaving the second ridge and the full width of the valley open. We added a second length of valley trough above the first, overlapping by 150mm, and cut it to a mitre at the top to fit flush against the ridge of the north wing roof.

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We made up a wooden board to go down the valley. Using a length of 2 x 6, we trimmed it down to 125mm wide, then planed bevels on the underside so that it rested on both sides of the valley. We could slate up to the board to get a neat edge, we screwed bits of batten across at intervals so we could use it to get up and down the valley.

We dusted off one of our home-made wooden roof ladders and fixed it in place opposite the side we need to slate up. With this, our aluminium ladders, we had pretty good access to the whole area of roof above the valley boards.

I boarded the gap between the scaffolding platform and the north wing roof with a 50mm timber platform resting on a timber screwed into the sarking, this meant we could place ladders right up to the bottom of the valley and had easy access to the valley board and wooden ladder.

And so so to work. We found YouTube clips showing valley troughs being installed, including neat ways to mark up slates to fit the valley. This involved turning the slate face down across the gap between the slating and the valley board and marking the gap on the valley slate. We then rotated the slate so the long edge was against the valley board and marked the vertical line up the slate from the first mark. By cutting along this line with the slate guillotine, we produced exactly the right shape to fit against the valley board and nail into place. Coincidentally, the angle of the valley was just about the same as the diagonal slop of the slates, so most of the valley sales were very similar in size. We used slate-&-halves throughout, up to the top of the valley and transitioned to slates running across the top of the north wing ridge. The point where the valleys intersect with the east wing roof will need a lead saddle across it to protect the tops of the valleys, this needs both sides of both valleys to be slated up. Slating the other side of the valley was effectively exactly the same, but we used the other wooden ladder on the other side of the valley. This ladder rested on slates so we wrapped rolls of hessian burlap round the long lengths to spread the load and avoid cracking the slates it was in contact with. The end result was slating projecting neatly over the valley trough by 50mm and a 125mm open space above he valley board.

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Insulating the east wing

Whilst getting the roof weathertight has been a priority, we have been pushing on with insulating the timber studwork against our outside walls. The idea is to create a fully insulated shell inside the outer stone walls. So it must run from the insulated upstands at floor level, up through the studwork, through the floor joists, up the truss supports and rafters and across the top collar, to meet the insulation coming up from the other side.

Insulating downstairs
We ordered 30 panels of 140mm PIR panels and got going. We dug out our battered and rusty Stanley Jetsaw and, after a bit of experimentation, discovered a) that the panels needed cutting around 5mm smaller than the measured dimensions and b) that it is tricky getting nice cut edges exactly at 90 degrees from the facing. So the panels will push into spaces, sometimes with the help of a bit of timber and club hammer, but usually have some gaps that we filled with foam. The latter was very good at wedging looser panels into place. We made decent progress working round the downstairs walls, including up towards the roofline in the gallery area. We will leave the top of the gallery area until we can set up a scaffolding tower inside.

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Insulating upstairs
We pondered how best to work up past the downstairs studwork into the attic trusses. The floor joists of the trusses rest on the studwork and support the rafters with a web of upright timbers each side. This is 400mm deep and has two triangular spaces that will need at least partially filling with insulation to avoid thermal bridging. On the east side, the outside edge of the uprights align with the studwork, so we can run the insulation straight upwards, filling the outermost triangle with wedges of insulation cut down from our leftover 100mm insulation boards and halved (the trusses are 50mm thick). So the insulation will be adjacent to the stonework, with a 26cm void inside, where we run plasterboard over the inner upright. The west side is slightly different because the truss timbers are offset outwards relative to the studwork, by about 10cm, due to the outward lean of parts of the west wall.

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This is good for the rooflights. We placed them low enough to be able to see out of, so they are also recessed outwards beyond the line of the inside wall. We can run plasterboard back into the space between the trusses either side, to get more light into the rooms. If we choose to, we could use the voids in other places for recessed shelving.

Insulating the roof
For the bays between trusses that do not have rooflights, we are running the panels up between the joists to the bottoms of the rafters, then running panels up between the lower part of the rafters to the top collars, at which point there will be room to use 300mm of conventional loft insulation. The rafters are 220mm deep so the 140mm insulation board leaves an 80mm void above the insulation, which connects directly down to the soffits, so meeting the building standard for ventilated space below the sarking boards.

Insulating round the rooflights
We are running the insulation up towards the frame for 120 cm above the top of the downstairs studwork, with a separate piece above bevelled and sloping at 45 degrees outwards to the sarking boards immediately below the bottom of the rooflight frame. We run the insulation horizontally from above the frame out to the bottom of the rafters and continue up to the top collar with another bevelled panel. We cut a 180mm wide piece of 25mm insulation board across the diagonal down the length into two bevelled sections and fitted these either side of the frame down to the bottom of the rafters. We also put strips of our left-over 25mm insulation on the other side of the rafters from the frame, to reduce cold bridging from the void. We filled small gaps with foam. The escape window was treated in much the same way, but because one edge does not butt up to a rafter, we built up the timber to match the profile of the trusses. We also built batten into the space below the frame to support the weight of people should it ever be used in anger. We also want to build a seat under the window.

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Starting the second roof

We moved the scaffolding round the other side of the east wing and began all over again. It took a couple of days to work up to the ridge, slating one side of the first rooflight, at which point we had new things to do.

Flashing over the ridge
We had run the lead flashing up the first (east facing) roof and stopped just short of the top-most soaker. We did the same on the west-facing side, then made up one extra length of flashing which we planned  to run up one side, fold over at 90 degrees (technically 96 degrees) and run down the other side to lap over the existing flashing. I anticipated herding cats, but it worked really simply and well, with the skirt forming a neat double-fold below the apex and the beading making a sharp-ish about turn in the grooves, where they intersected. I got it mortared over and left it to go off before the next step…

The top courses of slate
I calculated how to finish the roof up to the ridge, to be weatherproof. I was able to run another full course of slates that brought the top edge just about to 120mm from the ridge, this is just about where the bottom edge of the ridge tiles will sit. So I could fit a 260mm-height course at the 190mm spacing, nailing them in just above the course below and leaving room to nail a 130mm row above that, giving proper overlaps. If the roof is not quite fixed height, I can adjust the last two courses accordingly. I had to use the 45mm roof nails in place of the 38mm I used on the rest of the roof, because there were three rows of nails in a compressed space and they had to accommodate three full thicknesses of slate. Of course we had to do both sides of the roof, using our  23cm wide slates on the east side and the 26cm slates on the west.

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Fitting the (first two) ridge tiles
Ric advised us to fit the ridge tiles at the end of the working day, so we did not disturb them with hammering. The first one needed to flash into the lead flashing I had run over the ridge. I carefully peeled the fold in the skirt and pulled it out and up, to give room to fit a lead soaker behind it. This followed the profile of the ridge tile. Folding it without tearing it was a challenge!

Next we mixed a bucket of 1:2 lime mortar, slathered it either side of the apex, keeping the exposed membrane clear and slid the first ridge tile in under the soaker. I left the lead unfinished until the mortar had gone off. We had room to fit a second ridge tile in against the first, using a sprit level to get them lined up and finished. The following day, we formed the lead soaker over the profile of the ridge tile and pushed the lead skirt as far back in as it would go.

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Finishing the first roof

Slating up to the lower corner of the roof
We started the roof against the extension of the gable wall. This originally allowed large doors to open back over the opening that is becoming our big window. All the other corners end above our runs of facia boards, which project outside the building line – a consequence of lifting the roof by 45cm without building the stonework with it. So whilst most of the edges of the roof will be against coping stone, the bottom edges come past the padstones into open space. We handled this by projecting slates on the corners 50mm outwards as well as downwards. This involved quite a bit of cutting, plus we fixed the slates using A2 stainless screws to avoid stressing the fascia support by whacking roof nails in. The end-result was pretty good because it was neat, solid, but also unobtrusive.

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Slating round a soil vent pipe
We have three openings to make in the roof (two more if we install the MVHR). We have soil vent pipes above the east and west upstairs en-suites and a stovepipe in the north wing. The east wing soil pipe follows a circuitous route into the family bathroom from the inspection chamber outside, diagonally across the adjacent bedroom, up to the en-suite in what will be the wardrobe for the ground-floor bedroom, across the gable wall of the en-suite, then a dogs leg across until it is directly above where it entered the building, in what be another wardrobe (for the upstairs bedroom) and finally upwards and through the roof. The soil pipe in the west wing en-suite is handled similarly, our other soil pipe is all downstairs and we can get away with air-admittance valves to vent them.

We decided on old-fashioned lead slates for the SVPs, with the soil pipe projecting upwards through it by 600mm or so. We got a pair with the pipe opening at 45 degrees, near enough for our 42 degree slope. We cut away a short section of one sarking board and a sliver off the one immediately below it, to make a hole loose enough not to restrict soil pipe. We then spent a merry couple of hours cutting slates to fit around the upstand and flashing the lead slate in to be fully watertight. I added extra lead below it, fixed with double sided butyl tape, to give a good enough overlap onto the slates below. We left the upstand without pipe in it until we get round to doing our soil pipe – not far away now.

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Finishing off
We slated onwards and upwards, flashed lead over the soakers and mortared the lead in. Apart from the very top rows, which we will slate from the other side, that was the roof fully sorted and ready for guttering.

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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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Finishing the fascia panelling

The only rough edges on our fascia panels were where the runs finish at the gable end. There are two on the north end and one on the south – the east run of fascia ends against the stub of wall that extends out from the gable end. Ric filled in the ends with bits of fascia board then cut covers from a sheet of aluminium. They wrap under the bottom of the fascia board as the panels do, but have flaps that fold round the right angle over the adjacent panel and over the top onto the sarking boards.

We coated and cooked them along with three joiners to cover where these covers lap over the panels. We coated them whilst it was raining heavily and whilst the primer went on well, the top coat was very unsatisfactory, with a lot of spots of primer showing through. We left them a couple of days and re-did them when it was warm and sunny, it all went much better and they were all fit to put up. It was a quick job to hook the covers over the bottom of the fascia board and nail through the top flap. Then we lifted the eaves trays out of the way and nailed the joiners across the join between cover and panel. Very neat.

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Screeding the north wing

We got the eastern end of the north wing ready for screeding whilst we worked on the east wing. We laid three loops of heating pipe for the kitchen area and one for the pantry. We did not lay pipe under the stairs or along the part of the north wall where we might put cupboard units. We put the second manifold between the kitchen and dining areas, between the fireplace and the north wall – this will be cupboard space. We pressure tested the four loops, with blanking pipes in the other 6 pairs of ports and had two of the compression fittings leak at 6 bars. We fixed this by using PTFE tape.

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The rest of the north wing has been our workshop and has been quite cluttered with large and heavy items. We ended up clearing it out, finishing laying the insulation and mesh, installing and pressurising the underfloor heating pipe and screeding it as one (long) exercise, to be completed whist Ric is there.

Clearing the north wing
We cleared the small, loose stuff littering the floor easily enough and were left with the bigger items. We could not move stuff over the screed so everything had to go outside, across the courtyard and in through the big window. Each item was a challenge. The tables we carried between us. The aluminium folder we wheeled one end on our little trolley over scaffold board, The freezer housing we wheeled on the sack trolley at one end on scaffold planks. The washing machine and freezer fitted on the small trolley on scaffold boards. The woodworking machine was the challenge – we got it over the doorstep and across our pallet boardwalk on OSB laid on scaffold boards, then across the to window just on OSB. The run into the big window was too steep for us to push/pull, so we used our big orange ratchet straps wrapped around out external wall studwork and pulled it the last metre up and over the window sill. It was a miserable couple of hours, so we were more than glad to get it done.

Laying the last of the insulation
We laid the remaining full panels quite quickly and were left with a metre or so at the end and the area between the plant room and front door, which is where our pipes run. They all needed to surface in the plant room and it was quite complicated. We soldered the remaining lengths of 28mm copper pipe to the runs from the stove, ran them straight to the middle of the plant room, too a sharp left and brought them up against what will be the south wall, against the bottom of the stairs. We put a short length of 110mm brown pipe over the copper pipes to protect them from the screed. The cold water we ran over to the north wall, close to the rising main and both ends of the hot water loop next to the cold. The two pairs of feed/return pipes for the underfloor heating we pulled round to the east wall, mainly because they were a bit on the short side. They were a bit of a struggle to get anywhere near upright, so we left them at about 45 degrees. We filled in around the pipes with left-over chunks of board.

The services for the west wing we will run up the wall, through the joists to the upstairs en-suite then straight across the joists to the master bedroom en-suite. So we did not need to bury any additional pipes in the insulation, it was a case of taping all the joints and on with the next step.

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Laying the mesh and heating pipe.
The mesh was easy, two sheets cover the width of the north wing with a bit of overlap and we covered the remaining floor with just over 4 sheets, including outside doorways. We cut the mesh for expansions joints in all internal doorways, at the west end of the dining area and the east end of the kitchen (to keep to the 8 linear metres/40 square metres limits).

We did the remaining heating pipework as 6 loops. Three for the dining room area, one for the entrance lobby and adjacent cloakroom, one for the utility room and one for the hallway between north and west wings. These joined the four existing loops at the manifold halfway down the north wing.

Pressure testing was trouble-free, although filling 10 loops with air to 6 bars was a bit of a struggle for our little 6-litre compressor.

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Screeding
We split the screeding into four blocks. Timing was down to a) the availability of the hire bull float, b) us all being around all day and c) the weather being dry enough to mix screed.

Session one was small – the section between the east wing and the kitchen area, around 8 square metres.

Session two was the kitchen area down to the fireplace, 40 square metres.

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Session three was the dining room area from the fireplace down to the utility room/cloakroom, 40 square metres.

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Session four was the rest of the north wing up to the junction of the west wing.

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We were nominally laying 65mm  of screed, in practice the depth was often nearer 80-90mm, so we used quite a bit more screed. However, we ended up at the from door only mm out from the planned level, so we were right – it was the slab that was wonky, not our laying. We were knackered by the end and it will take a while to sink in that we can get going building the inside of the steading as soon as we get the slating finished. The inside already sounds rather more like empty rooms than a building site – a bit echoey.

Screeding the east wing

With the floor insulated and with the under floor heating pipes installed on mesh and pressure-tested, we were ready to screed the floor. We used a sand cement screed in the proportions of 1 part cement, 2 parts sharp sand and 2 parts quarry dust. We mixed it to a consistency where it would ball in the hand and break cleanly when pulled apart – not too sticky and not too dry. It was nonetheless quite dry and it really clagged up the mixer. We ended up scraping the barrel (literally) after a couple of mixes and giving it a good wash down every load. It took quite a few mixes to get the right consistency, when we did we speeded up significantly. An over-dry mix would not level properly and had a rough finish. An over-wet mix stuck to the float and was hard to get level. 

We barrowed the mix up and over the big window sill on scaffold planks, supported inside on small blocks of wood to keep the boards clear of the pipes. 

We did not use boards to mark out tramlines and use a board across the top to level the screed, the most popular technique on YouTube. Instead, Ric created small heaps, or spots, up to a metre apart. He used a float to flatten them down and a spirit level to get them all on the same level. These quickly became solid enough to use to work screed around them, using the spirit level to scrape out the high points. I was sceptical that i would be able to work accurately enough to help out, to my surprise it worked, and very well. It was accurate enough to be able to triangulate reliably enough between points to keep the surface level across the length and breath of the area. We dumped barrow loads of screed at a time between the spots, used a rake to spread it and either used an offcut of timber or our feet to tamp it down between and under the pipes. Then it was down to using a float and spirit level to smooth it out. Once we had a big enough area done, we used a hire bull float to smooth out the surface. It did a reasonable job, but we could have done with something rather heavier. 

The floor area is around 50 square metres, so we needed to worry about cracking due to expansion. This is a particular concern in tiled areas like the bathroom and kitchen. The guidance is to put expansion strips every 8 linear metres and every 40 square metres. So we ran a strip across the width of the east wing, between the second bedroom and the lounge at the south end. We cut a 65mm strip of 25mm insulation and sawed it down the middle. Where it crossed pipes, we cut notches on the strip and put a sleeving of polythene pipe insulation on the pipes either side of the foam strip. For good measure we also put expansion strips across all the doorways. 

Day 1
On day one we got the north bedroom, understair cupboard, bathroom and the connecting corridor done as far as the outside door. There was a lot of fiddling around and it was relatively slow. Ric did an excellent job around the pipes coming out of the floor to the manifold, including the 22mm pipes for hot and cold water and the flow & return for the heating. 

The trickiest area was the bathroom. This is to be a wet room, so we needed a surface that would drain water off the floor into the shower area. We had already cut out the insulation in the shower area, trimmed 25mm of the bottom and fixed it back. Ric worked it so that the door was level with the corridor but dropped slightly into the room. The floor was raised more at the edges in the corners and had very gentle slopes down to the middle of the room, then to the shower drain. The finish was a little rough because it was slow work and started to go off, however we are tiling it. It was a big relief to get a tricky job behind us.

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Day 2
Day 2 left us more than half the area to cover, but it was open so was faster going. We had interruptions because of heavy showers and a required visit to Peterhead, so we worked until 10:40pm to finish it.
We used the car headlights to light up the mixer and had bought two worklights for where we were screeding. We need the latter more generally as we race towards autumn and have the prospect of a waterproof roof. 

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