Mike

It included dot & dab plasterboard (which I've advised against) & fitting only a WC & basin. However there will be many other variables to make a 1:1 comparison.

Certification (to BS 476 : Part 22 : 1987 or BS EN 1634-1: 2014) that the combined door and lining (as a set), with appropriate ironmongery and installation methods, meets the FD30 standard. DIY mixes of doors, frames & intumescent strips don't meet the standard.

A friend has recently been quoted around £25K for a similar sized extension, so doesn't seem way off.

Although used in some of the Approved Documents, the word 'habitable' doesn't actually appear in the legislation, so isn't used for determining whether or not Building Regulations apply. However changing the number of rooms that are used for residential purposes does count as a 'material change of use', where a “room for residential purposes” means 'a room... which is used by one or more persons to live and sleep'. Which might well be deemed to include a utility room. (By way of comparison, Approved Document B - Fire Safety - does use the term 'habitable'; kitchens are habitable, but bathrooms are not). Changing the 'energy status' of a space - that is, heating or cooling the utility room - would require Building Regulations. Note that some newer buildings may have planning conditions preventing the conversion of a garage.

Legally, the design and the copyright remain the Architect's, unless the standard conditions of appointment have been explicitly changed. However - provided the architect has been paid as agreed - the person commissioning the architect will have at least an implicit licence permitting them and others working on the building to reproduce and use the drawings as necessary to construct the building.

Yes, electric heating is heavily penalised at the moment. SAP is changing next year and under the new calculations it should come out better.

Good to hear your progress! Yes, I've overpainted it with oils and emulsions and - provided the B I N is 100% dry (I'd give it a few days) you should be fine.

I've certainly done that.

Resistant = resists, not 100% proof against, however the crazing of the surface is a good camouflage if you fail to use a chopping board. Objectively, on the Mohs scale of hardness / scratch resistance - where 10 is most resistant - Glass (and therefore glazed lavastone) comes in at 5 with marble at 4. Granite scores 6, Dekton is rated at 8, diamond at 10 (if you afford diamond worktops). However Dekton can chip, granite and acidic foods don't mix, etc...

Stainless steel for affordable practicality. Glazed lavastone for those with deep pockets - strong & resistant to everything.

It's the householder's responsibility to respect any easements that exist. In terms of health & safety legislation - the Construction (Design and Management) Regulations 2015 - in a domestic situation it's the responsibility of the principal contractor to check out what lies beneath the ground, unless the principal designer has agreed to undertake responsibility. As others have said, from the planning perspective there is no requirement.

It depends what you want to achieve - it's not only the insulation quit - it's also all the other components of the partition, and whether you're only concerned with airborne sound, or if impact sound is an issue. Knauf and British Gypsum both produce useful guides. FWIW, the partitions on my next project will have staggered studs to physically & acoustically separate the two faces of the partition, with 1 layer of ply and 1 of plasterboard each side, 50mm acoustic quit between, and acoustic sealant at all edges and joints. If I was using all plasterboard instead of plasterboard + ply, that would give me 57dB nominal sound insulation.

That's surely how the current owner should have know that the main existed too. Not the sort of thing I'd forget that I had running under my garden.

The commercial systems are rather more sophisticated than that. Though you wouldn't want to make your tea with it. That's why it would need to be a topic for discussion. It may or may not be acceptable by itself or alongside other solutions.

Another option to discuss would be the option of a rainwater harvesting system - directing the runoff to a large tank that can be used for flushing WCs, washing machines and the like - you're recycling the water instead of disposing of it.

I've used it over various paints, no doubt including some that were acrylics, so I would expect it to be fine.

The only way to be sure of that is to specify exactly what you want them to do, in terms of scope, materials, quality, etc., and for them to confirm that's what they've done. As Markc says, the only way to get a line-by-line comparison is to commission someone to prepare a Bill of Quantities for you, with accompanying drawings and specifications. Whether it's worth doing that depends on the value of the work and your attitude to risk, among other factors.

FWIW I'll be installing something like the Schneider A9C15907 in France. There's an incentive for doing so - it helps to keep peak demand on the grid down, so transmission costs are reduced and standing charges are lower.

Looks like you may be replacing the entire 1st floor. And if the floor is in that state, what condition is the roof in? And are you required to replace like-with-like for conservation reasons, or to is is advisable or mandatory to reinforce everything with concrete due to earthquake risk? IMHO you need a local contractor or, better still, a structural engineer to advice you.

It is, although I'd choose expanded glass beads as they don't absorb moisture.

Well I'd have to put back a proper range in the kitchen. What were they thinking putting that 600mm one in there?

Sounds like nobody is requiring you to have one, so personally I wouldn't bother. And you may already have left it too late, unless you know for certain that your roofer is approved to provide one? Even if they can provide one, you need to check whether or not it's actually worth anything - the market has a poor reputation. Verify what is actually covered, what needs to happen before you can claim, and whether the insurance company is reputable. If it's a UK insurer regulated by the Financial Conduct Authority that would be a good start.

They don't charge anything, though the manufacturer's have to use an accredited laboratory. But it's your money and your choice :)

Because 1) You can make a proper comparison - they're independently tested using identical criteria that model 'real usage', rather than relying on the manufacturer's claims. 2) It's the go-to resource for choosing high-performing MVHR units. if a manufacturer has chosen to avoid assessment, why might that be? 3) Your energy bill will depend on your choice.

Stick to one of the models independently tested for the Passivhaus Institute: https://database.passivehouse.com/en/components/list/ventilation_small