SteeVeeDee

A cavity wall on he garage won't cost that much more in the grand scheme of things. It will be much more useful due to warmth and keep that foosty smell away.

I agree. When I was on the tools I regularly would see clients that had been manipulated by tradespeople. They were so inexperienced that they didn't know any better. Plus the friend/business line blurring could cause huge problems.

When I was a building contractor I learned to decline work on projects managed by architects. I also later declined working for architects' own homes. I sometimes wonder when they have the spare time to be making and issuing constant new drawings. Surely the skill of the architect is to visualize the project in advance so that when the project starts everything (wishful thinking) is already drawn and detailed? A great architect is a rare beast indeed but they can be absolutely fantastic to work with and the projects go smoothly, on budget, on time. Such a shame that they're so rare.

Aye, sometimes the effort and pay off don't align. Its always difficult making those decisions whether to reduce head height or not, and the effort required. Working overhead is such a pain in the backside and like you said, its only going to show slightly in alcoves. Personally, I always aim for bang-on straight, level, plumb, and true, simply because (apart from being correct) it tends to cause problems later and I cuss myself out for it.

30mm is too much to leave, plus the plasterers won't manage to get a good finish. All the systems mentioned are good. You've got enough height to go old school and do a 3/2" frame as well if you want. You've also got enough space for resilient bars if you want to make an acoustic ceiling, just make sure you don't fix through the resilient bar and the subframe. You know all this anyway so I'm not trying to teach you how to suck eggs. I battened a ceiling out recently to avoid losing too much space and I quickly remembered why I stopped doing that years ago. What a pain in the backside messing around with the shims.

Who's house is this? His or yours? You've hired someone patently unqualified for the job so you need to, at last, start thinking clearly and realistically. Was the structural engineer from him or you? If so ask him/her if the know a lawyer. Otherwise you could possibly contact the RICS or CIOB. I'm sorry this has happened to you but its horribly common. Do not let this person continue works but do so within your legal obligations. My guess would be that they will not have the correct health and safety policies, insurance, etc. There may be pincer movements you can do that arent't straight ahead.

Congratulations! What a lovely view!

There are always exceptions to the rule.

Why is the ridge tile missing? Is it dry fixed and you've just removed it for the photo? They say "fix the roof whilst the sun shines" so great time to do the repair. It may be worth causing a leak by using a hose. Decide on doing certain things in a certain place and check. You can try the scatter gun tactic at first but that may not tell you anything other than that you have a leak, which you already know. Just make sure to allow a few hours in between to avoid this. The pointing at the wall/flashing junction could be better. Noticed that the ridge tile was probably laid with mortar and removed. The membrane should be turned up at the flashings but this only matters if the water is bypassing them somehow. It doesn't appear that there is an opening below, are the flashings individual or part of a cavity tray? You may want to replace the individual step flashings with a more traditional longer step flashing and 6" overlap between each. The lead dressing over the tile should also be checked from the manufacturer and make sure that is correct.

Great reply and very interesting.

Ok, so thats one. There are a variety of reasons why he may be sought after. Define builder.

A decent carpenter will be able to measure up and can either order them for you and add a margin, or use that and order them yourself. I'd avoid having a builder anywhere near anything that's got tight tolerances and glass. You've got a few options by either going direct and doing it yourself, or getting the man fitting them to measure them. Be mindful that you can save a penny and lose a pound. Some tradesmen are happy to let you order them because it keeps them under the VAT threshold but the best prices are from trade suppliers. Its a toss up so pick whichever one you prefer.

Agreed. Private project managers can feel like an extravagance but if they solve problems and keep the project on track then their cost is covered. I've met a couple of bad ones but the majority tend to be pretty good. They stay busy by being professional and getting recommendations so are incentivised that way, rather than backhanders.

I agree on this. The supplier/manufacturers are generally pretty helpful.

There are two types of roof: pitched or leaking. Epdm is good as long as its not going to walked upon. It can be repaired but the patches look like a teenager's bike tyre after a while. Ideally its for dormer roofs out of sight, or below roof terrace decks where its covered by a walking surface system. Felt is the industry standard because it's got a predictable life span, it's cheap, companies are always available locally, it's easily repaired, and there are a wide variety of liquid compounds to prolong it's lifespan if necessary. GRP isn't very good and lasts far less than advertised. Its far too brittle for the task it's given. Fixing it to the substrate doesn't make any sense, particularly when one side is exposed to extremes of weather and the other is fixed down. Differential movement is an actual thing and shouldn't be ignored. Its also horribly toxic and cannot be recycled.