PeterW

So how much is a replacement Multipanel ..? Isn't that the other option..?

SE has got that a bit wrong - the issue on clay is when trees are removed, the water content on the clay goes out of balance and the clay expands to reach equilibrium which can take 9-12 months. The roots stop taking water the point at which the canopy is removed.

when were the trees cut down..? what is the ground composition..? Sand..? Clay..?

Why are you using lintels ..?? Periscope should be a flat block over looking at your build and only 225mm wide

You’re over thinking the bond issue. You won’t see the difference, and I’m pretty sure unless all your bricks are laser cut, you won’t get 100% accurate anyway so I wouldn’t worry as this is all below eye line anyway. Put them on faces that aren’t immediately visible like side elevations.

No it means that the extension as you see it cannot be more than half the width of that front elevation which looking at it is from the downpipe in the middle and about 15ft not including the porch..?? That could limit you to 7.5ft, not sure if it would include the porch - @DevilDamo ..? Thoughts...?

Have you checked the planning portal guide..? https://www.planningportal.co.uk/info/200130/common_projects/17/extensions/10

LoopCAD is the weapon of choice - can be downloaded with a 30 day licence from lots of places

Single speaker in marine ply and plasterboard ..?? I’m sure Adele won’t mind ....

Got the Triton one - it was on offer on Amazon and think it was £260 Takes a lot of cleaning unless you put a decent extractor on it

Take it you're not bothered about acoustics..???

I'm now considering using a 10x40mm steel bar with countersunk screws backed off by 30mm from the door and then use a standard rubber ramp in front of it. Behind will get a flow finish flooring compound

Yes it can - most good tap suppliers have flow restrictors for varying flows

18mm is standard thickness There are plenty of places that sell online and can send samples

That is a huge set of purlins !! I would not be too worried about the wall plate but do not remove or touch those purlins !!

bend it over on itself and zip tie

Lorry tarp ..?? Wrapping paper...????

Don't understand your logic..? You will have an even bigger issue with GSHP as that will need a bigger loop for higher output..?? I would probably go with a 14Kw (max single phase usually) ASHP for the heating, and a smaller 6Kw for the hot water if you're going that route but will need to go to a HP cylinder (min 300 litre, 400 better) and run that at night on E7. Heating then using the 14Kw into oversize rads or UFH if you are doing this sort of rebuild/refit and can get decent insulation under the floor.

TBH I would have had the window replaced - they are £200 and it would look better and also fit better

Looks like a really old roof to me that hasn't moved in ages. The collar ties there seem to be an afterthought and have 6" nails poking out - can't see but is there a ridge beam..?? I would go with a scissor truss here on every other rafter for safety - 1/3rd top/bottom from alternate sides, bolted through the rafters as per @Russell griffiths and then add in new ceiling rafters.

So why not do a 45 degree splay on your side from a middle wall (new) and front wall to give you the privacy and security but also retain the next door access..?

I think the issue on the Velux is that they have set it too high - rest looks fine

Any ASHP has a gas circuit. The difference is if it is air to water in the main unit. A split is normally one that has the gas /water heat exchanger in the house and connected with small bore refrigeration pipework. If it is a true split then it will be £3-400 to get it decommissioned and moved, assuming the gas is readily available as a lot of the older gasses are now being phased out. Find the history and the part numbers and lets have a look.

So you need the TS to get hot, and I would suggest using some sort of high heat source for that and then potentially go ASHP to do the grunt work getting it up to 45c. Log gasification or pellet are fine - pellet boilers have got much better over time and they are much more controllable. You could slave a UVC off the TS during the winter, and then just use the ASHP for the summer with an immersion backup.

How long is the run from the house..? You may find just having an adjustable IC or even the give in the pipes would work. Could also be cunning and do the direction change inside the manhole - This sort of thing would do it https://www.drainagecentral.co.uk/110mm-Channel-Drain-Pipe-Bend-90-Degrees-Plain-Ended-B2531 Would mean you got the manhole, rodding and direction change all in one place.