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.

Underfloor Heating II

We finished laying the heating pipes in the east wing and went on to the first half of the north wing, from the east wing opening down to the fireplace. This is mostly kitchen/family room, separated from the east wing by a small pantry, the bottom half of the east wing stairs and a short corridor running into the east wing.

We do not plan to heat the pantry, but laid a tiny loop of heating pipe, for frost protection. All north wing loops are to head back to what will be a cupboard behind our fireplace, that will house the second of three manifolds. We ran the pantry loop hard up against the north wall where we expect to have a run of kitchen units, to minimise clod spots on the kitchen floor. We did the kitchen proper as one zone of three loops. As with the lounge in the east wing, we ran the first loop as a spiral, tying down flow and return ends together on adjacent mesh wires, but leaving 4 wires free within the spiral. We ran it into the doorway between the kitchen and dining room, the doorway to the courtyard and the corridor at the foot of the stairs, but not under what will be kitchen units. The loop ran out just short of the middle of the room. We ran the second loop in the same way, on two of the four wires we had left in the first spiral. It filled in the doorways and corridor, reached the end of the first loop and we started filling the space left in the middle until it too ran out. The third loop we ran from one end only on one of the remaining pair of wires, reaching the middle after a quite short run, because there were no odd areas to fill. We finished the middle of the floor and ran the pipe back out on the last free wire, using only 75m of pipe. So we have four pairs of pipe ends between the fireplace and the wall. The remaining loops will be for the lounge (four), one shared one for the utility room, lobby and cloakroom and one for the corridor to the west wing.

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Meanwhile, we mounted one of our manifolds in the east wing under-stair cupboard, then spent a couple of hours trimming the ends of the loops to the correct length and fitting them into matching flow and return ports on the manifold, using the oddly-named eurocones, which are compression fittings. Five of the pairs of ports will not be used until we get the upstairs heating pipes laid, we used short lengths of spare tube to fill them in so we can pressure test the pipes we have laid. We closed off the valves that will connect the circulation pump and thermostatic mixing valve into the manifold. We closed off the automatic air bleed valves at the other end of the manifold and used a ¾” port on the feed side of the manifold to temporarily fit our 10-bar pressure gauge. We fitted a washing machine hose to the equivalent port on the return half and the other end of that into our compresser air line. We opened all the loops, then used the compressor to pressurise the whole lot to 2 bars. We fixed one air leak and carried on to 4, then 6, bars. We closed off the air filling port and left it overnight. It was, somewhat to my surprise, still exactly at 6 bars pressure, so passed the test. We left it pressurised as we screeded the east wing.

Underfloor Heating

We have bought two underfloor heating kits online. They each comprise a 10-port manifold, pump, valves and fittings and 10 x 100m rolls of 16mm PEX-Al-PEX barrier pipe. The latter has a middle layer of aluminium that means the pipe can be straightened and bent and will hold it shape, a property that we quickly appreciated.

There are dozens of suppliers, offering pretty much the same sort of thing. We chose ours because they did not include the stuff we do not need, especially the plastic clips that many people use to fix the pipes to the insulation. We are going to use 3mm wire mesh on a 100mm repeat (it is called wrapping mesh) instead and will use our existing bundle of wire ties to tie the pipes to the mesh. There are two benefits to using the mesh: It helps distribute the heat more quickly & evenly and it will make it much easier to plan and route the pipes. We are using a heat pump that will deliver water at 35c, so will use a 100mm pipe spacing rather than the normal 200mm. Because the pipe does not really like turns as sharp at 100mm, we will not loop the pipe side-to-side across and along the room, but lay the pipe in a spiral at 200mm intervals. When the pipe reaches the middle of the room, it has space to turn round and out, filling in the gap left by the pipe spiralling inwards. This does not require turns tighter than 200mm. It also has the benefit of evening out floor temperatures because hotter incoming water I running alongside cooler outgoing water. Having the mesh will really help get us clean, simple pipe runs – a bit like a dot-to-dot puzzle.

We got the mesh in the east wing laid and joined together with ties, then used a spray can of paint to mark our walls, doors and areas that do not need heating – wardrobes and, when we get into the north wing, kitchen cupboard units.

Then down to designing the pipe runs. A 100m roll of pipe will nominally cover 10 square metres of floor, less any pipe used running from the manifold to the room. In the east wing, the two bedrooms and bathroom will each use a single circuit, the public room at the far end will need two and the corridor will largely be filled out by the pipes running to and from the other rooms. We have an external coil pipe bender to make the corners in the pipe, but will see whether we need to get a proper bender.

When we got going with the pipe, it turned out to be quite manageable. We unrolled the pipe, straightened it and made the bends at corners, then used the wire ties and twizzler to fix the pipe down. It was all exactly as I had visualised it and was quite well behaved. For the public room (currently named the Room of Requirement), which used two loops of pipe, we opened out a roll of pipe for the first loop and ran both ends together from the manifold area in a spiral that left room for the second loop to go out and back. When the first loop was finished i.e. around the halfway length, we tied that down and ran the second loop in the space left by the first and filled up the area inside that the first loop did not reach. We even had enough pipe left over to cover the corridor leading from the understair cupboard to the Room of Requirement. We used exactly the full 200m of pipe, with none spare, it was a very close-run thing. Without thinking, I ran the external pipe bender along one end of the first loop, got to the middle of the length and only then realised that, having tied both ends of the pipe down as we worked our way in, there was no way to get it off the pipe. I had to destroy it by unwinding it, a beastly job. I will not replace it, the pipe is easy enough to bend safely without a bender.

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We have more to do once the pipe is laid and tied down. We need to lift the mesh by 10-15mm so that the pipes are in the middle on the screed, not the bottom. We need to pressure test the heating circuits before we lay the screed. For the latter, we have ordered a 10-bar pressure gauge that will fit temporarily onto the manifolds using a standard ¾” connector. We will use the compressor to pump air via a washing machine water pipe (also ¾”) into another connection on the manifold. We will pump the circuits up to 6 bars and leave them for several days to ensure they do not leak.

Powder Coating

Having decided on timber windows with powder-coated aluminium exteriors, it was not a big leap to then think about powder-coated
fascia boards. We even have a RAL colour. We drew up shortlists, took the ones that we both agreed on and haggled down to – 6004 blue green. As an aside, do not look for RAL colours online. What with different rendering between devices and poor translation from RAL to RGB/CMYK, it is inconsistent & misleading. We bought a physical RAL K7 Classic colour swatch and were aghast at the difference.

We need to be able to handle chunky lengths of aluminium around 2m long. Ric has specced out a design for a) an oven that will cook them at 180c and b) a bending machine . We will start ordering stuff as soon as we get on site in April. For the oven, we need…

• 0.7mm aluminium sheets 1250 x 2500 to form the oven casing
• 100mm loft insulation to insulate the oven
• strapping to hold the insulation in place
• a 2kW heater and a fan, to heat the oven & spread the heat
• a PID temperature controller and associated bits, to regulate the temperature
• a thermometer, to go at the other end of the oven from the controller, to show when the whole oven is at temperature
• a ‘D’ format kettle lead and connector
• cables, screws etc. to construct the oven and wire in the electrics
• fencing wire, to suspend the aluminium inside the oven as it cooks

The folding machine has a fixed part that the sheet of aluminium is held on and a moving part that pivots round 90 degrees, to bend the aluminium round a sharp angle. It is a fairly standard bit of workshop kit, but ours will be larger than average. We need…

• a 2.7m length of 127x76x13 I beam (UB) for the piece that pivots up
• a 2.7m length of 203x102x23 I beam (UB) for the piece that holds the sheet in place
• a 2.7m length of 75x75x8mm angle to fold the sheet around
• 4 lengths of scaffolding tube to use as legs
• weld-on hinges to attach the two lengths of I beam together i.e. to create the pivot point
• bolts to hold it together

We will probably use 0.5mm aluminium sheeting for the fascia and 0.7mm for the windows. The primer and powder coating both come in handy 20kg packs – we might just get away with one of each. We will doubtless have to improvise a bit to get the whole thing working.

Whilst on aluminium sheet, we have changed our minds on heating the up-stairs areas of the steading. The building warrant expects us to use radiators, we now want under-floor heating. The only practical way to do this without using up room height is to use aluminium spreader plates under the floor boards, with 50mm PIR insulation under the plates. However, commercially-manufactured plates are not designed for using heat pumps (35c water, requiring 100mm pipe spacing) on floors with joists at 600mm centres. We reckon we can make our own, more cheaply than getting someone else to make them up for us as a ‘special’. We are not sure whether we will need a separate folding machine.