Mike

And here's an extreme illustration: - this is what happened when I cut a hole through some plasterboard to rescue a bird(!) that was trapped. The 100mm glass fibre insulation behind the plasterboard was pretty pointless.

I've not heard of it, however I've just checked that is more-or less what the legislation says. If you occupy the building then the notice expires after 8 weeks. There is a get-out if you can obtain a final certificate for the part you have occupied, but that's probably only useful if you're occupying a self-contained zone: (6) An initial notice shall not cease to be in force by virtue of paragraphs (2) and (3) because part of a building or extension is occupied if a final certificate has been accepted in respect of that part. However there is also this: (7) A local authority may extend any period referred to in this regulation either before or after its expiry. That doesn't actually say that a private inspector has to hand back the work to the LABC, just that only the LA can extend it. So, in theory, unless there's some other relevant text, your private inspector (or you) could ask LABC to extend the notice, after which you could continue with the private inspector. No idea if anyone has ever tried that, and not sure that the LA would be prepared to do it unless they took it over, but you could give it a try.

On my current project most drivers will be tucked into the corners of cupboards. Where that's not possible they'll be in a secondary consumer unit, next to the main one, with one conduit for the main voltage cables between the switch and the driver, and another carrying 24V to the LEDs.

It's possible, but what's the advantage over your option 3 (Leave pebbledash in situ, inspect to make sure no cracks etc, fix EWI straight on top and render over)? Just seems to be adding unnecessary additional cost. Then that's another big tick in favour of rebuilding - underpinning isn't cheap and it's presence (especially if because of subsidence) may add to the cost of house insurance and put off potential future buyers.

And if you have a woodburner you're at a high risk of carbon monoxide poisoning too, unless it has its own separate air supply. Don't use it until you have adequate ventilation.

Though you may be able to add useful m² by building a basement, subject to permission. Theoretically 8 weeks from submission, but you'd need to check out other local applications to get an idea of the reality. Yes, that is a factor, but a difficult one.

It's not just the VAT. I've undertaken several deep renovations myself, as well as having managed & priced them commercially, and they always turns out to be more expensive than rebuilding would have been - unless you're doing much of the work & discounting the cost of your labour. In addition to strip-out costs, many things just take more time and/or cost more. For example, building a doorway into a new internal wall is more-or-less 'free' - the extra costs are roughly balanced out by saving 1.5m² of blockwork. On the other hand, knocking a hole through an existing wall, well that's a couple of days work + additional materials. Then there are things you find that you didn't expect that need fixing - walls, floors & ceilings out of level; botched DIY; sagging rafters; dry-rot; lead water mains; cracked sewers, whatever - which also takes more time to fix than fitting from new. And making an old house properly airtight - which is highly recommended - is almost always more complex because it wasn't considered as part of the original design. There are good reasons for not demolishing. Maybe you just want to tart it up & flip it. Maybe you need to live in it because you have nowhere else and a caravan is out. Maybe the building has a particular heritage value (whether listed or not). Or, as with my current project, maybe it's an apartment - which kind of rules out demolition! But if you do decide to renovate then do make sure that includes a thermal upgrade to at least Building Regs standards. Better than that if you're concerned about future energy costs and / the future additional value that it's likely to provide.

Provided you use semi-flexible insulation batts you cut them a little oversize and compress them a little, so that they push gently against each other from floor to ceiling and wall to wall, holding each other in place when supported by the studwork... Just found a pair of images to illustrate the above. This is hemp insulation on a wall about 1m wide x 2.6m high, self-supporting (left) before I put the studs in place (right). The batts here are 100mm thick, but the lowest (out of shot) was sawn through to about half that as the wall behind was out of plumb.

This.

One of these. Which one depends on the state of the pebbledash - in particular evidence of cracking or sounding hollow. However a deep retrofit will be more expensive and time-consuming that rebuiding. Unless you do lots yourself, in which case it may be cheaper but will take much longer... ...so give this very serious consideration!

Stanley Fatmax is a brand of Stanley Black & Decker, who also produce Dewalt. Stanly Fatmax fits between Dewalt (at the top) and Black & Decker and their stacking-toolbox systems are interchangeable. Fatmax & Dewalt share some components, but Fatmax tend to have a lower spec - which may or may not be important, depending on what your nephew plans to use them for. However I've not tried them myself (all my battery-powered tools are Dewalt, as are most of my mains tools) so can't comment on durability.

Don't take them out...

Here's the official info: https://www.gov.uk/product-safety-alerts-reports-recalls/product-safety-report-mk-electric-mk-essentials-electrical-three-pin-sockets-with-switches-2411-0130

No, you can just build in the hanger and add the joist later - just drop them in from above. Except where you need the lateral restraint straps too.

It's in the certification criteria - https://database.passivehouse.com/en/components/#certification-methods-info The effective dry heat recovery efficiency [is measured with] with balanced mass flows at external temperatures of between – 15 and + 10°C and dry extract air (ca. 20 °C) Presumably the worst reading is taken. However Heat Recovery Efficiency, as the name suggests, only measures heat recovered. On that basis a unit with expensive-to-run fans can look better than one with highly efficient ones. The Efficiency Ratio is the key figure that allows you to compare units like-for-like, taking into account the electricity used as well as the heat recovered.

The fixing brackets are reversible, so you also have the option of fixing them to the top of the ceiling - for example on to battens spanning between joists. Not if you're using Zehnder vents - they just push into the plenums. But if you're mixing and matching brands (VRGLs are a Lindlab compnent?) then you'll need to work it out.

Simpson have a few ranges of restraint hangers, such as this one: https://www.strongtie.co.uk/en-UK/products/safety-fast-lite-hanger-solid-joists-sflh

Is the unit installed the correct way round? Condensation would be expected in the section that exhausts to the outside air - warm moisture-laden internal air sheds water when it's cooled by the incoming air. On the air intake side the cold external air is warmed up, so can hold more moisture, therefore condensation is unlikely.

Almost, but it's necessary to distinguish between the airtightness layer and the vapour control layer. With a perfect airtightness layer, then there will be nothing to drive moisture through the vapour control layer into the insulation - see my text on the 3 purposes of airtightness on page 2. You won't achieve perfection but the airtightness layer is the most important of the two layers. So: - Where air can leak through a VCL into the insulation but get no further due to airtightness layer, the moisture transfer will be limited - Where air can leak through the insulation (through the gaps in or the absence of an airtightness layer) to the outside, the moisture transfer can be dramatic, as per the illustrations above. With time + care + testing, you can achieve very good airtightness. Using service cavities you can likely get a pretty well sealed VCL too, but its positioning means that it's more vulnerable to damage. I meant to comment on this yesterday, but it may also be that your sand is too sharp - try a bricklaying sand instead (or a blend with what you already have).

Provided you use semi-flexible insulation batts you cut them a little oversize and compress them a little, so that they push gently against each other from floor to ceiling and wall to wall, holding each other in place when supported by the studwork (at least once you get to 40 or 50mm of thickness). If any additional support is required (for example I had to do a mansard roof + a ceiling so everything was trying to fall in on me), then you can cut them to join behind a stud, and double up on studs to give them extra wide support if necessary. If you're careful, you can use lots of the offcuts, so that there's not much waste. BTW, talk to the manufacturer / supplier about suitable power saws to cut them with - you don't want to be using a hand saw if you have lots to do. Yes, you can certainly create a service cavity that way. However, as mentioned by @Redbeard & @Iceverge, VCLs don't give you a get-out-of-jail pass - not all moisture comes from inside, it's difficult to seal VCLs perfectly and an imperfect VCL can indeed be worse than no VCL. 'Smart' VCL membranes (those that change their vapour permeability from winter to summer) do allow moisture that would be otherwise be trapped by a traditional vapour barrier an escape route, but you still have to be sure that the structure dries out sufficiently in summer, rather than accumulating additional moisture each year - which would be catastrophic. Re the WUFI analysis, the usual computing adage of 'garbage in = garbage out' applies. And getting that right can be tricky too. This is why internal insulation can be difficult, and a key reason why external wall insulation is normally preferable where it's an option. Yes, Intello is a smart VCL.

Unless your wall is wet, my recommendation would be to either use flexible wood fibre (SteicoFlex or similar), or a similar product made from hemp (IndiBreathe Flex or similar). As mentioned in my post on the previous page, many natural insulations handle moisture vapour in a superior way compared to others. I'd use metal studwork and position this so that the insulation is gently squeezed behind the studs against the wall, to hold it in place in contact with your parge coat. It may be possible to fill the space between the studs with another layer of insulation; it's safest to ask the insulation manufacturer to advise on the thickness, but potentially that may be two 45mm layers, giving you 85mm thick overall (including 5mm compression on that 1st layer) from the wall to the face of the studwork. The manufacturer may also be able to advise on whether or not a vapour barrier is recommended over the top of this; making the structure airtight + installing MVHR (which will help control winter humidity) + the extent of potential rain penetration through the wall are also factors that affect this. If the insulation manufacturer can't give advice, you may need to commission someone to carry out a WUFI analysis. If you do need a vapour barrier, then you'd want to add a service cavity to the face of the studwork to run pipes and cables in. FWIW, this is more-or-less what I've done on my current project in France.

If this duct is running from the MVHR unit (or a manifold) to or from a ceiling terminal, and if the duct is on the warm side of the ceiling insulation, they you don't need to insulate the duct.

Looks good! HCLs are significantly more vapour permeable than cement-based mortars. To say more would require an analysis of the particular lime brand and mortar mix as permeability isn't directly rated to the NHL classification (which only defines compressive strength at 28 days). Although using a lime putty would provide superior performance I've not heard of anyone using it for the purpose, though there must be some who have.

And, to return to a debate discussed in the past, I'd run the pipework under the units in the kitchen & utility room too.

Blauberg are well known, but don't have any MVHR units in the Passivhaus database, which lists models independently tested to more accurate standards than those required in the UK and those used by manufacturers. So it's difficult to know how good it is. https://database.passivehouse.com/en/components/list/ventilation_small