Bit more progress.
Before
After
I've won a little bit of room which will help me minimise how far the boxing in of the pipes encroaches into the room. Mind you, took me best part of the day as I had to remake one of the solder joints three times as I just didn't seem to get the pipe clean enough. Also discovered that the depth of nut on the old compression coupling didn't match that of the new compression coupling. Trouble is I only discovered this when the olive had been compressed enough to stop it coming off the pipe stub but the nut was such that I could not fully tighten it up. So had to flip the pipe assembly over which meant I lost a little (15mm or so) on 'minimising the boxing in' scenario.
Decided to not apply the central heating inhibitor until I'd tried a leak test. Just as well as I thought it had all filled up and it was watertight and luckily happened to be sitting at the computer when I heard a gushing sound as water squirted out. Oops...luckily I'd removed the LED ceiling light and so the water disappeared down its hole and into a hastily positioned saucepan. Ssssh...don't tell SWMBO else she'd have me buying a new one.
I need to go down town and see if I can get some better pipe insulation as I don't want to dry the floorboards out. I already have a roll of Tri-oso type stuff and that will also go down between CH pipes and floorboards.
Here you can see all the ply infill panels. Sod's Law dictated that the floorboard edge joints run down between the infill panels and so I used a glue gun to keep the spacers in place. I'll be able to drill/screw through them when I fit the boards for real.
And we're up to the next level change - ie where the rising slope plateaus out and I can go flat again.
And Hallelujah...at last...something easy. The edge of the last floorboard on the slope takes me up just high enough to clear all the existing joists so no fettling required there.
The last floorboard took a fair bit of fettling underneath to clear this metal plate. As it turned out the plate never had an external plate fitted when it was put in by the builder 20+ years ago. Looking downstairs there has been zero movement in that timeframe and I was tempted to simply remove the plate. BUT..But Sod's Law being what it is, I balanced the relatively minor amount of extra work cutting out the underside of the floorboard on the table saw to clear the bolt thread and screw bolt heads against taking it all up again if that main oak beam started moving.
So tomorrow sees me glueing and pocket-holeing the infill panels then fitting the floorboards down for good.