More concrete blocks

The only things stopping us putting up the remaining roof trusses on the north wing are the incomplete front door and one of the kitchen windows. The front door is a job for another day because it needs a good weeks work to build up the stonework, including either side of the garage door – it would not be easy to do them separately. The kitchen window, however, is just missing the concrete blocks above the lintels that will support the trusses, a half-days work. We had mild, still and mostly sunny weather for the duration of the visit. We checked our weather forecasts and decided to risk it. We used cement mortar because a) we had only one bag of lime left over from the summer and I was not sure what state it was in and b) the cement was in plastic bags and was still usable. 

It took two mixes of mortar and one bucket mixed by hand to lay one course of blocks widthways across the concrete and granite lintels and two courses lengthways along the inside edge of the wall. We covered it for a couple of days just in case of sudden frosts, then cleared it all off. 

• 

• 

• 

• 

So when we move up, we can install 28 or so trusses along the wall whilst we finish the front door.

Christmas 2018

We had a couple of jobs in mind over Christmas/New Year. Firstly, to get a load of our possessions up and stored in our immediate neighbour’s large shed/garage. Secondly, we want to temporarily board up windows and doors in the north and east wings, so that as the roof goes on we can start to dry them out and create a reasonably protected working area. 

As it happened the weather was unseasonably warm, still & sunny, so we got a small stretch of wallhead blockwork finished and the missing sarking board over the east wing trusses. So it did turn out to be a quite productive visit. It has knocked a week off our schedule for when we move up permanently in April 2019. 

We got a Christmas bonus – our replacement big lintel, for the garage door, was waiting for us nine months after we ordered the original! 

Truss preparation – completing wallheads

Blockwork: In July we completed rebuilding the east wing wall where we slapped open two new windows. We did not get time to lay the additional 4 courses of blockwork over the top to raise the wallhead to the design height, so this was the first task for this visit. Given the change of design to attic trusses in the east wing, we laid the blockwork right against the inside edge of the wall. The bearing point on the attic trusses is right next to the uprights that support the floor joists and is 190mm wide, so we wanted to minimise the amount of block we would cut away getting the trusses to bear on the wallhead. The job was straightforward, two courses of block laid across the wall, two courses laid along the wall, we were done in two short days.

Wallplates: It turned out we have an abundance of wallplate – I bought the right amount from Ellon Timber, but they were included (undocumented) with the roof trusses. Being Scotland, it was 100mm x 22mm x 4800mm, it was a quick job to bed the onto 10mm of lime mortar, tap them out level and leave them a day to go off. We put several screws through each board into the blockwork the following day.

More wallhead blockwork

A background job was completing the top blockwork on the west wall of the east wing, right up to the junction with the north wing. From this point, across to the north gable-end, the roof trusses will be supported on timberwork. The first half had been done a while back, on top of existing granite walling. It needed continuing over the new walling we constructed back in April.

The wall bows outwards significantly in the middle, probably due to badly designed roof timbers, but of course we need the gap between wallheads on east & west walls to be the same along the length of the roof i.e. it needs to be straight. The top blockwork is 440mm wide, whilst the wall is 500mm and we wanted to minimise overhangs at the ends on in the middle. The existing section had started at the outside edge of the wall, by mid wall it was overhanging the inner edge by a few cm. I carried on with the blockwork, following a straight line that aimed at the dummy truss on the north gable-end wall. By the time I reached the junction with the south wall of the north wing, the blockwork was running roughly down the middle of the wall, but was straight and level.

July visit

I was at the steading for a full week in early July, with Ric. The aim was to prepare for our September visit, where we want to get roof trusses up on the east wing and, if practical, part of the north wing.
To summarise where we are with the east wing…

• West wall (facing the courtyard): We rebuilt the doorway and installed lintels over the door and small window in April, then built rubble wall above the lintels to old wallhead height. We still need to lay blockwork to raise the roof to the design height.
• South gable-end: The parapet and retaining stones will need raising to the new roof height but can be done after the trusses go on. At the same time, we need to remove the stub of a concrete lintel that was embedded into the courtyard corner.
• East wall: The pre-existing doorway has been blocked out as a window and we completed the stonework up to sill height back in April. Last Christmas we opened out a section of wall to install two windows. The backing blockwork for one window is complete, the other is not blocked out because we plan to install quoins for a splayed window and do not really know how that will play out. We need to do the stonework (sills, quoins, lintels) for all three windows, complete the backing blockwork, lay the rubble walling, then raise the wallhead to the design height with the four courses of blockwork.
• North gable-end: This needs one side tidying up, replacing missing quoins and the retaining stone (for the coping). The parapet will need raising to the new roof height, but can be done after the trusses go on.

So most of the work on this block translates into:

1. Getting possession of the 41 granite lintels we ordered in March from Lantoom Quarry, Liskeard, Cornwall.
2. Converting three of the lintels into window sills for the three window openings down the east wall of the east wing.
3. Installing the sills, building quoins up the sides of the window openings and placing concrete (structural) and granite (decorative) lintels.
4. Completing the inner skin of concrete blocks up to old wallhead height, where we had demolished original wall.
5. Re-building granite rubble walling in front of the concrete blocks, around and over the window openings, up to old wallhead height.
6. Lay the four courses of concrete blocks above the walling, to raise the roof to the designed height.

Ric was confident we could do it, I was prepared to give it a shot. Being mid-year in northern latitudes, I could allow myself as long working days as I could stand – it gets light at 4am and dark after 10pm!

I brought the strimmer up with me to tame the grass, nettles, docks & thistles, but quickly realised that it was a bit late. The hot, dry weather meant that the perennial weeds had seeded and gone over already and had woody stems – strimming them would be dissatisfying and not very useful.

A flying visit

We had planned a while ago to fly up to the steading over the late-May bank holiday. We wanted to meet up with our granite lintels and sills, however this was not to be. They were delayed and Ric headed south early because there was not a huge amount to do. We went ahead with our visit because we had bought the tickets and car parking, got the dog booked into kennels etc. It was a sound decision – we had four days of wall-to-wall sunshine, low winds and moderate temperatures – warmer and sunnier than down south.

We had a bit of a mare getting home, though – we got back 13 hours later than scheduled. We got to the airport just after 7pm for an 8.35 flight. At 8pm we were told it would be delayed until 10.20pm, then 11.20pm. Then, after 11pm, someone spotted that flightradar was showing the incoming flight, having circled over the airport for a while, heading back over Dundee. We knew it had landed in Glasgow before it was officially announced that a) it was going to refuel and then b) that it was too foggy to land in Aberdeen, so our flight was cancelled. We were near the front of the queue at the Menzies Aviation desk where one hapless individual had to sort out over 100 concerned passenger, so we had only an hour to wait to get sorted out. We had little choice – wait two days for the evening flight out from Aberdeen or transfer to Glasgow for the 7am flight to Luton. So we taxied across to Glasgow, arriving 5am, got our flight out, got a train from Luton to Gatwick, transferred from the south terminal to north then got a bus back to the long stay car park. We knew which zone we had parked in, but it took about 40 minutes to find the car, we had not noted down the row number. Anyway it was a fairly quick run home, getting back about 2.30pm.

Back to the steading: We decided at the get-go on two areas of work – tidying our hedging and carrying on with concrete blockwork.

Weeding & tidying

With spring well underway, our hedging needed weeding and tidying up. In fact we could usefully have run the strimmer over most of the garden, but I had taken it south last year so we could keep our allotment in order. I will take it back up in July.

Jill worked her way round the entire plot, pulling weeds, removing tree guards, removing dead stuff and replacing the guards. The failure rate is still reasonably low, even in the areas that flooded over the winter, probably less than 1 in 10 overall. Most plants have broken well clear of the tree tubes and are starting to bush out, but for whatever reason, we have patches where they are languishing – it may be the wrong species in the wrong place or just poor ground. We had problems over the winter with the wind blowing some of our tree netting over and the rabbits had chewed the bark off a couple of our fruit trees. We will look to do a proper inventory later in the year and buy a small batch of replacements. We will probably not do anything where one plant has failed, we will expect the others around it to fill up the gap.

Concrete Blockwork

Ric had left the mobile bay of scaffolding in the master bedroom area of the west wing, for us. I carried on from where Ric had left off – he had constructed the north gable-end as high as the sill for the upstairs window, then worked around the west wall getting blockwork up to old wallhead height. I blocked out a shortish length of original wall to new wallhead height (four courses of blockwork, 2 across the width of the wall, 2 along). I then worked on the south gable-end. This had been taken partly up to ground-floor lintel height last September. I built it up level to old wallhead height, going round each corner and tying it in to the original walls. I then extended just the gable-end upwards to the same height as Ric has with the north gable-end i.e. to sill level for the upper story window. We ran out of time & mortar to do more, with just two blocks not mortared into place. Looking at the gable-end that we have part-raised to new roof height, we will need a few more blocks to tie the gable-end in to the raised blockwork on either side wall – at worst we might need to use wall-ties.

We can carry on with the concrete blocks, getting the west wing gable-ends completed, raising the last piece of old wall to new wallhead height and blocking over the new piece of wall we finished in the east wing. Beyond that we need to get building the granite skin in front of the blockwork in the remainder of the east wing. And that needs us to have the lintels and sills.

Looking at my spreadsheet, we have bought 34 pallets of blocks to date: 2912 concrete blocks, with around 450 not yet used. Six pallets-worth of 10N ones went underground to get our foundations up to DPC. The rest have been 7N and above ground level. With the tops of two gable-ends to complete and nearly  half the wallheads still to raise, we might only need an additional 600 blocks – another 7 pallets! I doubt we will be sorry to see the end of them. In theory every single one of them will disappear from view.

Gable-end facelift

The east wing of the steading has two gable-ends. The south end is complete & intact. The north end is sound, but in poor condition at the upper end. The retaining stones  that held the coping stones in place are long gone, as are the upper quoin stones. Some of the coping stones were missing, the remainder were threatening to slide off and we removed them a couple of years ago, for safety. This gable-end needs sorting out before we can get the roof on, plus we need to raise the roof by 45cm (four courses of 100mm concrete blocks + mortar lines) over the original wallhead height, so both gable-ends need to be raised as well.

The gable-ends are to be constructed (as they are now) in the traditional Scottish manner. The outer 300mm is a parapet that should be 150mm above the slating, with the coping stone above that. The remaining 200mm of wall is rough-finished, just under the sarking board and slates. The sarking projects out from the last truss, which will be tied in to the stonework of the gable-end. DPC runs under the coping, down the parapet and over the sarking, overlapping with the roof breather membrane. We flash lead over the exposed DPC, down onto the slating

Tidying up the north gable-end is a tricky proposition – we need to work out where the new roofline will be, given what we know about the proposed construction (raised-tie trusses) and a guess about the depth of the top chord above the wallplate (we assume 180mm at the 42-degree angle). We assume 22mm depth for sarking and 30mm for the slating. We calculated, quite accurately, from that where the retaining stones need to sit, so we can build the gable-end corners to the right height to support the retaining stones.

Enter stage right, a dummy roof truss that is exactly the right size to fit across the raised wallheads and exactly the right slope (42 degrees from horizontal). Ric created the truss and propped one side up in the correct position, using a length of wood. We cross-checked the dimensions and slope, realised it was 50mm too narrow, reconstructed it in-situ and screwed it onto the stonework to stop it blowing away. So now we could work out accurately where the retaining stones need to rest.

Enter stage left, the batch of granite we bought from our neighbour a couple of years ago. It is mostly quoin stones but, significantly, has two pairs of retaining stones. These are like over-size quoins, with a distinctive hollow cut into one end of the upper surface. The hollow allows the lowest coping stone to lodge in it and supports the next coping stone up the slope and so on. They are about the largest stones we will be handling apart from the lintel over the garage door.

With a level to work to, Ric rebuilt one side of the gable-end with quoin stones, let it go off for a couple of days, then we very gingerly hoisted the rather massive retaining stone into place. It was then a quick job to run blockwork up the inside of the wall, with just enough room for the finished roof to cross over to meet the parapet. Ric will repeat the operation on the other side of the gable end. We will leave completion of the parapet until we have the roof on, just in case we need to make fine adjustments.

Concrete blocks and lintels

To recap, all our new and replacement rubble walling must be constructed with an inner skin of standard concrete blocks laid on their sides. We tie the blockwork in to existing walling with ‘swallow-tail’ wall ties that screw into sound boulders in the old wall, with the swallow-tail part eventually getting mortared into the blockwork. We include stainless steel mesh reinforcement strips, bedded in the blockwork mortar and sticking out the side, to be able to tie the granite outer skin to.
When we are ready to build the outer skin, we paint a liquid DPM (Synthaprufe or, in our case, a cheaper substitute) on the outer face of the blocks, wait the short time for it to go off, then build the 250-300mm skin of granite rubble, as close as possible in style to the adjacent walling. Given the old walling was 450-500mm thick, some of the boulders are too wide for the new construction – we use the feathers & tare to split them.
There is no reason why the replacement walling should look any different to the original, once it is all picked and pointed.

Also to recap, all the wallheads are to be raised by 450mm. This is to lift the roof by some 45cm and give us headroom in the upper storeys of the east and west wings. We are doing the same to the single-storey north wing, to maintain the proportions of the building as a whole. We do this by laying two courses of concrete blocks widthways across the wall, lined up with the inside edge. On top of this we place two courses of blocks laid lengthways, also aligned with the inner face of the wall. The roof trusses will bear directly on wallplates laid on the raised blockwork. We completed some of this blockwork a year or two back, then got distracted onto other priorities.

Back last September, Ric and my youngest brother, Geoff, started building up the inner skin of concrete blocks across most of the building. They made good progress, getting many of our window openings defined and building the blockwork for the two gable ends in the west wing, to ground floor lintel height. We got a lot done, but had more still to do. Ric has since put concrete structural lintels over two windows and a door in the west wall of the east wing and raised the blockwork above these to the height of the old wall head. He had bult up to new wallhead heights on the remaining granite wall.

On arrival, we carried on the good work. Ric worked on the east wall of the east wing, forming the northern of the two new windows we opened up at Christmas. He could not block out the other window because we will use our splayed quoin stones and will not know the exact size and shape until we do it. This done, he took the top off the north gable end, removed the wooden inner lintel and put concrete ones in its place. He built up the inner course of concrete blockwork. The outer granite lintel is still in good condition, so was left well alone. He moved to the northwest gable wall and built blockwork above one of out Catnic steel beams. He kept going until he reached sill heights for the upstairs window.

We started by placing concrete lintels over all openings in the north wing that were ready. Where this was over new blockwork, we had room to place 2 out of the three required lintels – the third one will have to wait for us to build the granite outer course. We tidied up the blockwork above, to the level of the old wallheads, but cannot raise it to the new height until the granite outer skin is built. Over original walling, we placed all three concrete lintels, just leaving room at the front for the decorative granite lintel, then raised the wallhead by the required 45cm. We had a bit of an issue running the raised wallhead across the concrete structural lintels, the bottom course of blocks tended overhang the outside edge and sag down. We sorted that by using old slate on thinner beds of mortar, it was much better at supporting the blocks until the mortar went off. By the end of our visit, the north wing had raised blockwork over the entire length bar two openings on each side that need granite rubble to be rebuilt to old wallhead height.

This all had a transformative effect – what had been gappy tooth-like islands of old wall quite quickly became coherent and well defined runs. With the floor slab in place, it is easy to visualise the internal layout and get a reasonable feel for what the finished structure will look like. Exciting times, though there is still a lot to do before we can get the roof on.

2018 shopping list

As far as we know, we need to buy the following:

• Granite lintels, cills and thresholds – from Lantoom Quarry
• Around half our concrete structural lintels – Having bought a whole load of 1.5m and 1.8m lengths a year or so ago, we need to get 18 x 1.2m, 8 x 1.5m and 8 x 1.8m ones. We can do this by buying 4 x 3m & 10 x 3.6m lintels and cutting them.
• An initial tonne of NHL 3.5 lime.
• A truckload of sand, probably from the Bridgend quarry near Tipperty, for lime mortar
• A heavy canvas that we can arrange over scaffolding to protect us and the walling from the elements.
• A tarpaulin to cover the sand.
• A truck load of 440 x 215 x 100 concrete blocks
• DPC and other sundries
• Locking castors for our scaffolding so we can run a bay around the concrete slab for working inside.
• A silt trap so we can install our linear drain in front of our garage & front door.
• Blockmix, sand & cement to build a concrete apron in front of the garage up to the linear drain.
• A bilge pump to clear sludge out from our concrete tank

Depending on progress with walls, we may need:

• Structural timber to support roof trusses at each end of the north wing (where we demolished the internal rubble walls)
• Timber for wallplates, truss clips, tie-down straps etc.
• Roof trusses
• Sarking boarding
• Breather membrane and tape (may be a cheap temporary fix to protect the roof, to be replaced when we are ready to slate)

Methinks this will stretch our finances until we can sell our current house and I retire.

TLC for walls

Measuring the walls: The walls in our east & west legs of the steading need extending upwards with concrete blocks, to raise the roof trusses and ensure enough height in our upper storeys. Our single-storey section will also have the blockwork, to maintain the proportions of the roof. During our last visit we marked up floor levels and worked out lower and upper storey heights. This confirmed that, with separate raised-tie trusses and shallow easijoists, we will have minimum 2.2m ceiling upstairs and down.

During this visit we need to check whether the truss-bearing walls are 1) straight, 2) level and 3) parallel, so that we can make sure our blockwork will be fit to bear the roof trusses. We already knew that one wall on our east two-storey section has a bow in it and is not vertical. So I used a surveyors tape measure, the level & staff and a builders line and spent a part-day scrambling up and down ladders.

Our conclusions:

1. The single storey walls in the north section are straight and level, but systematically get closer together by 20mm west –> east over the 22m length. Not bad! The north wall is 30mm higher than the south wall. I am counting on that not actually mattering too much, but will aim to raise the level of the mortar capping before I do the blockwork.
2. The west section is in a bad state with only sections of wall remaining at wallhead height. What is there is level, straight and parallel, within a few cm.
3. The east section is more complete and the east wall is straight and level. The west wall is equal distances from the east wall at each gable-end, but bows out within a few metres of the south end by 120mm max. Otherwise it is level. The blockwork needs to accommodate the bulge without risky overhanging inside or out. It will need to project over the inside face of the wall by some 60mm, over the few metres of maximum bulge.

The architect designed the roof to let us take up this sort of variation without affecting the appearance of the roof, as well as lifting the inside of the roof. The raised-tie trusses have two lengths of timber on the ties, one above the other. The lower bears on the blockwork, the upper carries on down and over the edge of the wall. We will trim the ends of these timbers to line up with a fascia that we can fit the guttering to. The soffit underneath we will shape to fit the variable line of the wall.

Tools for the job: Ladder, surveyors tape measure, builders line, level & staff.

Checking how straight the walls are.

Capping the walls: We will start capping the walls even though we have not got any of the doorways/windows sorted out. These will need sills at the bottoms, quoin stones up the sides and lintels over the tops.

The lintels include four 100mm wide x 212mm high structural lintels over each opening with minimum 150mm support each end, aligned with  the inside face of the wall.

In the single-storey north section, the structural timbers are at the level of the base of the blockwork and the roof timbers will hide the lintels, elsewhere we will need decorative outer lintels.

Many of the existing granite lintels are cracked, we will be looking far and wide for replacements.

If we can find enough good granite, we will cut stone sills, rather than use the concrete ones the architect designed in.

We got the scaffolding out and constructed four bays along the north-most wall. I used the builders line and a long scaffolding board to establish the high points in the wallhead, confirming they were suitably horizontal. We mixed barrow loads of 1:4 mortar with plasticiser and built-up the hollows in the wallhead with stones and mortar. We levelled it out horizontally between the high points using a spirit level. It was reasonably quick and it went off enough after 8 hours or so to start on the blockwork.

Loads of 1:6 mortar.

I used a bucket to lug it up.

The wall needed a bit of work to level it up.

The mortar down and level.

Not a bad finish.

Blockwork on the wallheads: The blocks are standard 7N 100mm x 212mm x 440mm. I laid two courses, longways across the wall and aligned with the inside vertical. On that I laid two courses laid lengthways, again aligned with the inside vertical. The result was not pretty, but satisfyingly perfectly straight and level. I did not get the wall finished, other priorities got in the way, but it looks like the blockwork will not be a headache.

By my calculations, the north section will have walls around 2.4m above finished floor. The trusses will give a lie-in long enough to install 5 50cm x 90cm velux-style roof lights along each side. Then a level ceiling between, around 2.8m above finished floor level. Should be impressive and, with a room width of just over 4m, I really hope it does not look as tunnel-like as some of the steading properties we have checked on the ASPC website.

A truck-load of blocks.

The first two courses were laid cross-ways, aligned with the inside edge of the wall.

Then two courses length-ways on top. Total lift, 44cm.