Mike

Spit on! I shouldn't rely to stuff at this time of the night...

Why did he design it then?! The best solution would, of course, be switch to a warm roof design. Failing that, you could add breather vents in the flat roof - Klober do a range, for example, but so do others. I'm not sure where the Building Regs have hidden the provisions on ventilating roofs, but it used to require vents equivalent to a % of the roof area in the case of large / complex roofs. If nobody else chips in, then the manufacturer should know, if your architect doesn't.

Me too, for the quality of the finish as much as anything else (provided you find a good plasterer). However well dot & dab is done, you're guaranteed to see the joints in at least some lighting conditions.

I wouldn't put the ceiling supply vents right in the room corners & so close to the walls, particularly in the bedrooms. Many such vents use the Coanda effect (which is recommended) so that the air disperses evenly across the ceiling. However, if a wall is in the way, the air will be deflected down the wall and may cause an unwanted draft; from memory 750mm is the recommended minimum distance from a wall. Zehnder's Luna S (and probably others) have an optional deflector that can be inserted to get around that. What @JohnMo says. Just add a double pipe to the extract over the sink. Zehnder's advice is to place the extract near a shower, but not within / over it.

Good to see the pictures - it looks excellent!

When the storm hits is a great opportunity to detect the leaks - if the wind is strong you'll be able to detect if by feel. Just as useful as a second blower-door test!

Yes, the Regulations require fire door sets; that is a door + frame tested & certified together.

Well it would be against the Building Regulations - though you'd only be prosecuted if you survived the carbon monoxide poisoning. You'd need a 'room sealed' stove installed in according to the manufacturer's guidance - I've only seen horizontal of under-floor supply pipes. The alternative is to knock a hole in the wall and install a permanently-open vent, in accordance with the dimensions in Part J of the Building Regs. If it's only a decorative effect you want, block the flues, install a TV screen inside an old stove and set it to show a flame video.

Sounds good, though I was thinking of something a little different! A sill would normally project through the render, where the red arrow is below (looking at the outside now, not the inside). But if you're rendering before the window's fitted, the render will be in the way, unless you make some provision for it, or have another solution - stone sub-sill maybe?

Slight deviation from the topic, but what are you doing for the window sills? They're not part of the window - or they are and you're pre-shaping the render to fit?

A very interesting history! I've not seen earth mortar before, though in several regions of France they built (as recently as 100 years ago and occasionally still today) 5 or 6 storey buildings from a mix of earth and stones, compressed in-situ (pizé) - so it can be very strong, if protected from the weather - they're usually covered in a lime or clay render. You'd certainly never use cement on them. I've just taken a look online and, if you're not already found it, there's a short pdf on clay mortars here: http://openarchive.icomos.org/1801/1/Historic Environment Scotland_Mortars for Masonry Buildings.pdf which, states that "most clay-bonded walls were externally pointed or harled with lime mortar to provide additional protection from the weather". There is a phone number at the back for Historic Scotland's technical advice department, though it looks like you've already talked to them. But maybe they can help with the identify the mix used, if you can find any original pointing mortar behind the existing. Having just looked it up, the process for what we now call 'natural hydraulic lime' wasn't developed until 1756, so lime putty would no doubt have been used - perhaps burnt & slaked on the estate if there is limestone in the region. Lime putty & sand, probably using a 1:3 mix, would therefore be my fist choice. That would mean repointing it slowly, starting no earlier than Easter so it has the best drying weather. There are courses you can go on to learn more if that interests you. Failing that, I'd go with the 3:1 NHL3.5 to sand, as per @jfb.

Suggest that with your reasoning & see what they say. I've used Tescon Profil too - it's easy enough to use, just takes a little time. Have some acetone on standby to clean your hands and scissors as it's rather sticky.

Good idea. I'll report back... That's possible. As above, it's nominally set to 40°C, but the dial on an an immersion stat isn't a precision instrument and the only temperature gauge is the one on the manifold (the one reading 38°C), so I've no way of knowing how close the Willis is to 40°C in reality. It will be getting a set of sensors & a Pi control system once the rest of the refurb is done - in time for next winter, I hope!

If the build is as old as a 600mm thick rubble-filled wall suggests, then the chances are that it's lime mortar, so I'd repoint in that to maintain / restore the vapour permeability & flexibility of the original mortar. You'd need to knock through the existing pointing to see what's behind if you think the original could have been cement-based, but that's only been commonly used since start of the 20th century. 1:3 NHL3.5 or NHL5 to sand would be the easy mix; since it's granite the latter would typically be chosen to match the hardness of the stone (NHL5 is usually, though not necessarily, stronger than NHL3.5). Lime putty would be the traditional material with superior properties (more permeable & flexible), but would be harder to use on granite - it would take longer to dry - and isn't suitable if the wall is regularly wet. Having said all that, I'm not a lime expert.

I aim for 7.5mm (all round) to give some tolerance - so it it ends up being 5mm or 10mm, no problem. I wouldn't object to 10mm too violently - it's just that if it ends up at 12.5mm in practice, then it starts getting fat for the external sealant. I'd ask them what their plans are for underneath - it could be that they'll also fix the window using mechanical brackets down the sides. Or they may plan to use temporary wedges (not all the way through) while the foam sets.