Temp

Im not sure I would install UFH without finding out. We have 80mm of PIR in our floor between battens and wish we had more.

Does it remove all Permitted development? What's the exact wording?

Just about any solution will have some sort of "upstand" requirement on a flat roof (including the sun tunnels).

Presumably you want each button to sound a different chime so you know which door to go to, and the three chime boxes are for coverage in different parts of the house? Quick google found this range can do that.. https://doorchimesuk.co.uk/catalog/product_info.php?products_id=629 That model supports lots of different wiring options including mains and built in transformers. The circuit below is just one possibility based on their option B using an external transformer and chimes in parallel. You would run two core cables for the push buttons and three core to the chimes all to a central location like the CU where the transformer and a junction box is located. You might consider running extra cores to the pushbuttons as spares or future use. https://doorchimesuk.co.uk/pdf/CROMA_230.pdf It says each chime box needs 12V at 0.5A so I'd use something like a 12V AC 2A transformer. With more time it might be possible to eliminate the external transformer using one of the other wiring options.

Perhaps look at a stranded CAT network cable?

Does it need to be a sun pipe? There are quite a lot of regular roof lights around. The key is to find a good installer as its important to get the upstand built correctly to the manufacturers spec so it doesn't leak. They can be made less than 150mm high which is the normal allowance before Planning Permission is needed. See page 38.. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/830643/190910_Tech_Guide_for_publishing.pdf Source: https://toughenedglasssystems.co.uk/product/skylights-rooflights-1000-1000/?gclid=Cj0KCQiA4L2BBhCvARIsAO0SBdYDHw4pi1LTL9uE49WF2s7X-UEy1KGVPUxOO5Y4Yf-2WbykSDWT_r8aAtZUEALw_wcB

Welcome to the forum.

Time to sell shares in house builders?

Is there enough insulation in the floor for UFH?

Perhaps make sure he knows how to do lead work or get someone experienced to do that?

House too air tight? No air brick?

I Sounds like he only has one stat (a Nest) for whole house. So yes all loops are either on or off together. If the Nest controls the UFH loop pump and boiler then no need for loop actuators at all. If they are just used for balancing it makes sense for them to be powered up (eg open) all the time to avoid accidental recalibration cycles.

+1 Should be tax free. It can be hard for a novice builder to make money actually building a house. Dont always believe the figures they quote on Grand Designs. You might make most of the money just getting PP and selling it to a developer. You could add covenants precluding them constructing a basement if you want or giving you a share of the profit if they reapply for a different/larger building.

Your best bet would be to build the new place for yourself and move in tor at least 3 years. Rent out your current property. CIL - None as self builders are exempt. VAT - reclaimed on materials, not paid at all on labour. Standard rated on architect. CGT - Probably none if you sell your current property as for most of the time its been your Principle Private Residence. Remember to make a will as IHT could be significant.

Be careful.. If you build to rent them out i don't think you can reclaim the VAT. https://www.macfarlanes.com/what-we-think/in-depth/2017/build-to-rent-vat-issues/#:~:text=Typically a residential developer will,purchase price for the site.

Is anyone likely to complain? If not you could just build it and see what happens. If someone complains the planners will send you a letter saying you need planning permission and you can make a retrospective application. If its refused you can appeal. If that fails you would have to reduce the height or knock it down. If the planners take no action for 4 years then you can apply for a certificate of lawfulness on the grounds they can no longer take enforcement action.

I would suggest getting a heat loss calculation from someone not trying to sell you ASHP. What boiler do you currently have?

We put in a rainwater collection tank but its only used to water the garden and the car so no need for filters etc. Doubt it pays for itself but is handy in a drought.

As I recall the manufacturer also has to approve their socket for use in a bathroom/humid area.

Welcome to the forum. Can I recommend you beef up the insulation and pay attention to how its installed. If there is one issue with ASHP that comes up regularly it appears to be undersizing - specifically the heat loss being greater than expected.

Perhaps you could put a flourescent dye in the system that woukdn't evaporate away?

You can't tell. At best you can say its less than the volume of the expansion vessel because there is still some pressure in the system.

37 x ?? Some buildings only have small ceiling rafters rather than loft floor joists. In other words they are only intended to hold up plasterboard not for people to walk about on or store things up there. If you want to store things up there or convert the loft to storage space the loft floor may need reinforcing.

I think that might be the only place in planning law where a completion time limit is specified? Are there any others?

In Belgium they say... Build your first house for your enemy, your second for a friend and the third one for you.