PeterW

They will be 2” black iron - hence the monster flanged pump ..!!

You will probably be on a mix of 28/22/15 depending on the routing etc. 4” sounds odd, sure it’s not a support column ..??!

Felt looks knackered anyway - take it the neighbour wasn’t interested in having theirs done too..?

How close to the tank (vertically) can you get the boiler ..? Wall hung 45kW gas system boiler would keep a 400 litre horizontal UVC happy and give you plenty of water. Just re-route the supply pipes to the oil boiler connections and use the same bits. Any reason to remove the pipework etc ..? That circ pump is a beast and you’ll need to replace all of the pipework before that goes as a standard pump won’t cope with 1 1/4" steel pipework volumes.

That’s rigid rockwool as it’s used on process pipes and possibly here due to the size of the pipework..! So where is the current hot water tank and what size is it ..? A 32mm pipe will provide volume but at what pressure ..? Ideally you want 3 bar dynamic pressure but I wonder if you will get that. I don’t think tbh you will get a combi to do that flow regardless - at full chat you’re wanting 30-40 litres / min through showers and that’s not achievable with standard domestic combi boilers. You could do some type of domino setup but you’re complicating matters and LPG is not that cheap either when you’re burning lots of it. In terms of pipework, I would possibly leave well alone as it will be a decent thick wall black iron pipe - possibly galvanised. As close to the new boiler return as possible I would put a pair of magnaclean type units that can take the crud out - get the ones with the filters in, not just the magnets. A pair in parallel allows you to filter through one whilst you service the other and also picks up equal quantities of crud in each.

Anyone wanting replacement Stanley knives, Screwfix are selling their two pack with blades for less than the price of a standard knife - £4.99 for two knives plus blades. https://www.screwfix.com/p/stanley-classic-retractable-utility-knife-fixed-utility-knife-2-pack/464hg

Slightly less than that of being hit by a meteorite whilst swimming with sharks whilst wrapped in bacon after winning the euromillions… . I would seriously get on with the build and ignore the issue as any asbestos would have been cement bound plus the wind will have carried anything far away from the house.

Had an open gas I’ve not used for about 8 months and used it today and was all good. The batteries on the paslodes go - they are about £20 for 2 generic ones on eBay as they are Ni-Cad so worth swapping.

Use ready mix mortar.

It’s not so much the gas but the lubricant in the cartridges that is the difference. That’s why you get the mucky marks with cheap gas and when you service the guns there is a lot of carbon in the cylinders.

Yep - I’ve had issues with Fischer gas. I now only use Paslode gas (IM350) and nails really don’t matter tbh. You can get 2 from S’Fix or TS for about £16 each so they aren’t expensive. That’s going to do 3000 plus nails.

Spiral is better for heat transfer overall and less hot spots

reasonable to whom ..? You’re not a construction expert, he is. You have a legal background, he doesn’t. What is reasonable to the man on the top deck of the No38 Clapham Ombibus ..?? Interesting discussion in court where a judge would decide if you had created an unfair contract term and awarded against you on that basis. In truth, an LDs clause is only useful when you’ve got legal judgement and agreement for full and material breach of contract, and tbh that would be long in the future so isn’t it better to sit down over a cuppa and a pack of chocolate hobnobs and talk it through ..?

yep aware of what it is, but if you’re digging up a floor to renovate then it’s irrelevant. LABC have an “approved detail” but it’s notoriously difficult to deal with and last check it was near 3 times the cost of a concrete floor.

Why limecrete..? If the floor is coming up you’re putting a DPM and insulation in to meet BRegs so limecrete is pointless

How much oil do you currently use ..?

I converted an old inspection pit into a wine cellar on a conversion and it was pretty easy to do but was already “there” so nothing structural required other than the lid. The warranty company specifically exclude it from the warranty, and tbh I do wonder how much more effort it has added as there have been since completion some minor damp issues that needed internal tanking. You would need to properly ventilate any space with a combustion appliance in it, and in honesty you can find space for a cylinder in a cupboard and MVRH in an attic as it’s only the same size as a large suitcase.

@Loz I don’t know the full spec but doing a quick fag packet, even with a 3.6N block and a reasonable end bearing load, a 225mm padstone is more than adequate. The key is that the beam isn’t overlapping the padstone. It’s also worth noting this is a steel with a flange so the padstone isn't required under the front flange - your builder has installed one so tbh they have gone over the spec required. I would really not be pushing or changing this with the BCO as the builder has done a fair job with that - SEng has gone over spec by the looks of it and there are bigger problems on builds - doubt BCO would even notice and it’s going nowhere.

No idea on the 400mm padstone spec on that as I can’t see why it wasn’t just 7N blocks as the load is negligible. I would leave it and move on.

That only looks big because of span not weight - the roof is the only load isn’t it or is there some sort of additional wall going above ..? Padstones look like they’ve been cut from a 1200mm concrete lintel hence the size…. Not the best I’ve seen but not the worst - the two lintels with a welded plate will stop it all going anywhere.

Paint with bitumen paint, build a cardboard “dam” about 2” around the steel and then fill with expanding foam then concrete it in.

Why use tiles ..? Board over with ply and then lead sheet ..?

Meant tell you what the neighbours had done ….

Meter would be at the house end.

BC isn’t contracted to provide that to you unless you pay them - do you know if it’s LABC or private BC..? As @joe90 says, a decent contractor can give you an indication in an hour or two - get a couple of trial pits dug and it will be £150 well spent.