Mike

Provided you have a master plan, roll it all into one application. Provide you're with LA Building Control they're unlikely to worry about when you complete - I know one project that must have lasted 20 years - though a private company may not be so accommodating (or may go bust in that timescale). As a bonus, if you get approval under the current Regs then any updates won't apply (they normally only apply to new applications).

Yes, it's possible :)

I'm probably unusual in that until recently I'd always cut mitres by hand. That's changed for my current project, but rather than a choosing a dedicated mitre saw I've chosen a track saw for additional flexibility (I'll be building various items of fitted furniture, starting with the kitchen). It could be worth looking at as an alternative but, it depends what you need to cut and in what quantity.

A firewall is a generic term. A compartment wall is a fire-resistant wall that subdivides a building into separate sections.

There's no requirement for fire dampers on a regular domestic MVHR system. The low air flow of isn't going to feed the fire with much additional oxygen, and keeping it running may help a little in venting some of the fumes, which are often a more immediate problem than the flames. I suspect that the biggest danger for MVHR in a fire would be fumes given off from meting plastic MVHR pipes, rather than anything else.

If you're planning a shower, then just choose 50mm diameter pipe. And make sure that the maximum flow capacity of the shower trap is more than the flow from the shower head(s).

Not sure, but there's a UK Carbon Border Adjustment Mechanism on the way that will levy a carbon fee on the most carbon intensive imports, unless the originating country has already levied a carbon price on them.

Yes, for the avoidance of doubt if you, as the client, don't appoint anyone, then the legal responsibility for both roles is all yours :)

That's not such a trivial decision now that there's a 10-year enforcement period (plus the possibility of an unlimited fine and/or up to 2 years imprisonment - though presumably much less for that for an insulation offence).

It would have to be done, as would @Sven7's. When heating a warehouse by more than 2-3 °C or so (the minimum necessary to avoid frost), then the entire building would need a thermal upgrade to meet the requirements of Building Regulations, unless it's already insulated to the required standard. Though the standard is no doubt still lower than Poland / Germany would require. I imagine the same would apply to summer cooling, though I'm less familiar with the non-domestic Regs these days. If heating is limited to frost-protection in the warehouse section, then only the offices would need to be insulated.

If it's not too close to the hob it could. Another possibility may be to run concealed ducting boxed in over the top of the kitchen cupboards, if you have any, to give more flexibility.

Yes, as per @BotusBuild's photos. It's not required to vent the rooms, however you appear to have 8 ducts pumping air into the ground floor, and you need to pump that same amount of air out from somewhere. If you have only 4 extract pipes, the airflow in them will (on average) therefore have to be twice as fast, and that speed could be more than recommended to avoid noise. You'd need the calculations to know if that's so, but it's possible. You do need extract directly from the kitchen, but away from the hob, and ideally on the far side so that the air flows across the room. As a compromise a wall-mounted vent could work (in the kitchen-dining room wall), unless you want to make to make a feature of a suspended metal pipe & vent.

Don't use chemicals. I use a pressure washer with water only and it works no problem.

You could certainly feed 2 separate manifolds, one for each side of the beam.

If you are building a new house, it's entirely possible to achieve well below 2. As you mentioned in your first post, the Passivhaus standard specifies a maximum of 0.6 ACH and thousands of those have been built. I've seen air test results mentioned below 0.2, though that is exceptional. However achieving that does depend an a high standard of work and attention to detail that you'll only get by using a well trained staff with hawk-eyed supervision (preferably your own). If you're using a single main contractor then you could specify achieving that (0.6 ACH @ 50 Pa) as an essential requirement. If you split it into packages, then you may literally need to take matters into your own hands, and allow enough time for it. Still a flawed assumption. It assumes you have house at ambient outside temp and its the coldest day and you never recover any heat until until at full temp. +1. On top of that, your UFCH will result in fairly constant temperature throughout the day, even if you heat it only during off-peak hours. It's not at all like a radiator system where the heating comes on for a few hours in the morning and evening and needs to respond quickly to achieve the required temperatures, before temperatures drop significantly while it's off. It's not sensible to design the system to be sized to heat the building from cold within X hours; instead it need only be sized to maintain normal temperature on the coldest day of the year. That does mean that if you move in in December you may need to plug in some electric radiators for a while, but after that you should be good.

Always a good idea if you can. However, at least in England & Wales, it is necessary for sewers to be vented to the open air in places so that the sewer gasses - which are toxic and can be explosive - can safely escape. That's normally required at the head of the sewer run, and every few properties (often 5) along the way. That is covered by Part H of the Building Regs, section 1.33: Ventilated discharge stacks may be terminated inside a building when fitted with air admittance valves complying with BS EN 12380:2002. Where these valves are used they should not adversely affect the amount of ventilation necessary for the below ground system which is normally provided by open stacks of the sanitary pipework. If you are required to have an open stack, there are a couple things that you could consider. One possibility, if you're not more than 2 stories high, is reducing the pipe diameter to 75mm diameter(Section 1.32). Another, if you have a nearby detached garage, is to extend the sewer to that, then run the vent pipe out of the garage roof. And, as @Thorfun suggests, it's normally possible to hide top of the pipe with a vent tile.

From the apparent thickness of the wall in the image, I suspect a cavity wall. A measurement of the actual wall thickness would give a good idea. If it is a cavity wall I wouldn't accept the door as installed. @Conor has mentioned several problems, and for a cavity wall I'd add the bypassing of (1) any cavity wall insulation, current or future (2), the vertical DPCs that should have been used where the cavity was closed, and (3) the cavity tray that theoretically should be above the lintel. I'd wonder what they've done about the DPC at floor level too.

Me too. And oil-filled ones can make a real mess when they leak.

@Redbeard is correct - there is a requirement to ventilate a timber frame cavity. No - air contains moisture, and if you lower the temperature enough it will condense, with or without a VCL (although it's sustained high relative humidity that's the problem, rather than the incidence of condensation). The presence / absence / continuity of a vapour control layer will however affect the flow of moisture vapour passing into (and out of) the insulation from / to the room, as will the presence / absence of good controlled ventilation within the room. You also have moisture tracking through the wall from outside, which no VCL will control - from rain, for example - which can be a bigger factor than moisture from internal sources. A ventilated gap behind the insulation can be essential or useful in some specific circumstances - for example if the wall is so irregular that a gap between the wall and the insulation in unavoidable in places (unventilated gaps are always to be avoided), or if the wall is subject to driving rain and it's not feasible to render it / apply a vapour-permiable sealant, or when wanting to achieve very low U-values.

And generate hydrogen sulphide - which is toxic, corrosive & flammable.

I wouldn't touch them myself, but that's a personal reaction to the grotty 20- or 30-year-old panels we used to rip out back in the 90s. The technology is now much better and they are generally well regarded.

I can't help you there - I'm able to do it myself. But no doubt someone else will be able to give you a clue. Think of the heating oil you'll save, rather than the cost :) Most products will have manufacturer's recommendations or BBA certificates to support their use so, if you present everything professionally and on paper it need not be a big issue, at least not for thermal insulation.

Someone will have to do you SAP calculations, so ask them to include the report - much cheaper than paying lawyers to sort out the mess + the cost of rectification afterwards. If they do it properly and include the supporting evidence there should be no grounds for the BCO to dispute it.

It does - see Appendix A, page 75.

No, it's not wide open to interpretation. Part L 4.13 defines it: If achieving the U-value in Table 4.3, column (b) either: a. is not technically or functionally feasible or b. would not achieve a simple payback of 15 years or less then the element should be upgraded to the lowest U-value that both: a. is technically and functionally feasible and b. can achieve a simple payback not exceeding 15 years. Generally a thermal element once upgraded should not have a U-value greater than 0.7W/(m3'K). A lesser standard for the thermal element may be acceptable where work complies with Part C of the Building Regulations on protection from the harmful effects of interstitial and surface condensation.