Onoff

I'd think about insulation under the floor, like 150mm min. If you're laying a concrete slab then why not incorporate UFH pipes now even if you never use them? You'll want the walls insulated too. Pointless not too. At that size I'd have put a trench in with soil & water pipes coming up through the slab as future proofing. Decide on your plan where you might later on want a WC / shower room.

I had a Vaillant boiler in a rental with BG's top cover package for years. It was annually serviced by them along with multiple call outs and failures along the way. Not once did any of the engineers mention there was no mag filter fitted or recommend doing so. It got to the point different BG engineers were saying different things. One would order parts then another turn up to fit them saying they were the wrong ones. Another did suggest a power flush might work. I got so fed up I outed BG and employed a family friend to fit a new boiler a lot cheaper than BG. He did attempt to power flush the old system first to cure the old boiler but to no avail. At the outset he said he'd attempt it but it was unlikely to do much. Think he charged around £300 for the flush. He did add cleaner & leave the apprentice there all day with the flush rig running saying he wanted to see "clear water" running out of it before he called yay or nay on the boiler. Sure he said modern boilers have quite a small heat exchanger that's prone to blocking which is why the system must be kept clean and have inhibitors in it. Something too about, again modern,heat exchanger materials being prone to corroding / blocking.

The small 20mm ducts are for Cat-6e cables for the EV charger, PV, gate intercom, CCTV etc. I'll use a shop vac to suck/blow draw strings through them.

I just PUSHED a 16mm² SWA and two 20mm conduits through a 21m 63/50 corrugated duct. No draw wire and 4 bends on the run. Thanks to mine and my lad's patented, 3D printed bell end esque pushy thing and a good dose of lube!

You should really have had a power flush at the time of the new boiler maybe? A cruddy old system can as I understand it block even a newish boiler. Old man had BG install a new boiler and they didn't flush the old system first. Had repeated issues thereafter. Changed multiple parts and at one point even removed the mag filter they had previously fitted. Utter farce tbh.

Power flushing won't necessarily work if your boiler is goosed.

It won't set particularly well and be a very weak mix if you're talking about a standard bag of concrete. For an 800kg bag of ballast you'd need x5 20kg bags for an 8:1 concrete mix or x10 20 20kg bags for a 4:1 mix. You might achieve a circa 500kg barrel weight with a well vibrated mix, probably a bit under.

ChatGPT says:

I would clean that up with a bleach solution and scrubbing brush then apply shower tanking paint and see what happens.

@zoothorn put one in his riverside shed / cabin as well:

Neatly cut and stick some insulated pb around the faces? You'd have to mitre the corners to ensure the insulation layer is continuous.

Some cold bridging maybe? Make airtight & insulate?

Our first Starlink, bought from Costco in the UK was faulty out of the box. Called the US helpline. New one was delivered the next day if I recall. Customer service is brilliant.

We have Starlink. Hassle free by and large and the support service is excellent if you need to talk to them (we had an initial hardware failure when we first got it).

In the absence of an EIC then an EICR usually satisfies for rentals etc. Let's face it there's no way you'll get hold of the original sparks.

In terms of certification then getting an EICR done on the whole install is the way forward in order to verify what's there now. Electrical Installation Condition Report. What was the "PIR", Periodic Inspection Report.

Or tubbies...

I thought it was OTT at first I was hinting at what I think you're calling a fork lift, the green thing, is in fact a telehandler! 😂

Long stainless steel studding chem fixed into footings and passing up in the cavity to secure the wall plate.

You had a forklift as well as a telehandler?

I've one of these bad boys: https://www.howetools.co.uk/makita-dur368az-twin-18v-brush-cutter

Illbrück FM330 skins up like rubber and really tough rubber at that. It's actually quite noticeable when you cut it compared to even Soudal products which were my previous goto.

DeWalt Bolster, comfy from out of the box but lucky if they don't fall apart within 6 months! 😡

Bigger men, bigger shovels! Taylor, Gilbreth?