To deny neighbour access to render extension?

Also with it being mm away. How is the guttering / rain run being dealt with.

As they were the only neighbours not legally notified of the work they didn’t know about it!

Yes, let them, but get a written agreement as to the timespan of the work and that they will replace/repair everything that is damaged, including any trodden plants, re-turfing required where they've knackered the lawn, fully tidying up, etc.

Sadly lots of tradesmen don't give a toss about the damage/incovenience, so you need something in writing beforehand to get them and your neighbours obligated to put things right and do the job as quickly as possible.

on which ground?

But just because it's legal does not mean it's not a shitty thing to build.

If you are refusing because you don’t like the extension, that’s petty. Presumably you could have objected?

You say that the wall has been built "within millimeters of the shared fence".

How thick is the render going to be? Are they going to claim that it's impossible to put the shared fence beck into it's previous position?

I'd be inclined to say no to your neighbours.

I would not let them do this and I would guess anyone who is saying to just let the do it has never been in this position themselves.

When building the extension your neighbours could have factored in access etc, they didn’t. They assumed you would be happy with the inconvenience and mess of them using your garden.

If you give access OP and there is damage/mess it could be very difficult to get anything in compensation from the builder, the neighbour would probably say it’s not their problem. You have no guarantee how long they will take either. There is nothing to make them complete it in a set time.

The only way I would do this is with a sum of money up front and a legal agreement citing time frames and the agreement to put right damage. No builders will do this, tells you all you need to know.

I would draw up a legal agreement. They have to make everything good..and you are the sole judge of that. They have to pay you 5000 pounds for the trouble and loss of use of your garden while they do the work. The work has to be completed by x date and every day past that date they have to pay you an extra 500 pounds. The 5000 pounds is to be paid up front and then they have to out an additional 5000 pounds into an escrow or third party holder account (managed by the lawyer who draws up the agreement) to only bereturned to them when you are satisfied that everything has been made good. If they havent completed it satisfactorily by x date the money os yours to make it good yourself.

Adjust the amounts to whatever you want so that if you have to completely rebuild the fence from new and buy new plants etc, it will cover it

There isn't a PWA. Given that they didn't get one, as far as I can remember (from my own experience), is that having breached that particular law (civil) the neighbours lose the right to access OP's land and are automatically assumed to be responsible for any or all damage to her property.
I would be worried about the foundations tbh, and would want to know the depth of OP's foundations and those of the new wall.
If they were happy to not follow the rules about PWA, I wouldn't trust them to do anything further properly.
When we did our PWA, our neighbours chose the surveyor, took loads of photographs and the builder had to supply copies of the plans and his company insurance policy. We get on well with them, but they were very particular about getting everything done properly to protect all parties.

you never know what you may need to ask them in the future?
if you refuse you have ugly beize block facing you rather than clean rendering

it doesnt take long one dsy should do it surely

Being so close I think it should have a party wall agreement. I am also surprised they are allowed to go so close under permitted development.

If you want to be awkward a more effective method would be querying those points with your local council.

Why not ask to choose the colour of the render that you would like to look at?

Just let them but tell them it must be outside of all school holidays and after summer. Alternatively, if they cant access to render they should have done nice bricks or something else that doesnt need render!!!

Let them render it. Otherwise you will be left with a unfinished breeze block wall in your garden. Surely you are cutting off your nose to spite your face?

I also agree with the camera
and I would take date stamped photo to show how things are, in which condition so they can't pretend it wasn't them

hard no from me

They don't care about blocking your lights, why should you be inconvenienced even further? These entitled CF are nightmare neighbours!

I might avoid any argument by allowing them "access" on your property, but a firm no in writing for moving, damaging, replacing and touching any of what is already there.
If they needed to move half your belongings, they should have thought about it and ask BEFORE starting the work.

Ask for a written confirmation of a new fence and seating area. Your choice, and see they’ve purchased and it’s been delivered and written agreement it will be installed in an agreed timeframe.

As they didn’t discuss this ‘problem’ with OP beforehand, they obviously knew they were taking things too far. Give as good as you are getting, I would.

Sorry OP. In my earlier post had not seen that they are using permitted development. But there are height and other restrictions on permitted development if close to a boundary. Can you check out that they are complying strictly. It seems completely unreasonable of them to have built as they have, requiring access from yours, which they cannot expect as a matter of course.

Absolutely this, similar situation our side - neighbours asked if they could remove trees and wall that made up our boundary, promised they would put back to how it was… 18 months later there was still no boundary between us and we had the hassle of stopping our dog getting out. I paid for a boundary fence even though we didn’t own that side and our son built their wall up to 6ft as they’d laid drainage pipes on our side of the boundary that prevented a fence going all the way along. They said they would ask the renderer to do both side of the wall but went back on that so now it’s up to us to sort out the mess. Whatever you do - get it in writing.

I think the only consideration is do you trust your neighbours enough to want to help them out?
If you think they will keep to any ( perfectly reasonable) agreement about timescales and reinstatement then it might be neighbourly to let them go ahead.
If you don’t then say no. I disagree with people who suggest that they may be able to obtain a court order allowing access. This is a new extension. It does not require ‘maintenance’. What they need to do is part of the initial build, and something they should have organised as part of this.
If you also chose to build nearly up to your boundary you would have to find a way of doing so without accessing their property. It can’t be impossible for them to do the same. You are under no obligation to help just because it makes things easier for them.
You are getting all of the disruption and they are getting the benefit, so only let the work go ahead is you wish to be helpful.

Get a camera up asap covering this area.
Do not trust them to be honest and decent.

They chose to build with no space to access for maintenance, that is on them.

Sensible people leave enough space for this very reason.

If they are having a new extension built, they should have planned for how it would be maintained. Not just putting on render now, but painting it in future for example. It is not up to you to inconvenience your own property by taking down fence, workmen coming into your space, or anything else, so they should have built it with their maintenance needs in mind, accessible from their own side of the boundary. Did they need planning permission for the extension? If so, this should have been considered in the plans. Maybe they built beyond the footprint they were given permission for? If they did have pp check that they have kept to it accurately.
I can't believe all posters on here OP urging you to agree to their unreasonable request. I would not do it.

In what way? I'd be more concerned about the space, there won't be any airflow, are there windows above the wall.

This. I wouldn't attempt something like this without trying to get the neighbour on board first.