Party wall garage on boundary

[ISthisOKatWork]

Hi, I wonder if anyone can help please.
My neighbour is planning to knock down and rebuild a garage on the boundary - it's only a metre from my house and their property is down a hill so there is a bit of a retaining wall (approx 1m high). They plan to keep the wall on the boundary intact and redo the rest.
I am concerned about light as it is the main light source to our house and they are intending to add solar panels to the roof (main reason for the rebuild as far as I understand). They've said in the party wall agreement that they'll lower the roof if possible due to beams - not sure how any beams will affect this given they're knocking everything down except the wall on the boundary.
They haven't mentioned that they've used a surveyor for this project.

Questions

1. I haven't seen planning application - is this required?
2. Should they have a surveyor and should I see the report?
3. If I sign the party wall act agreement today does that mean I have no come back if my house starts subsiding?

Thank you so much for any help anyone can provide.

1. Garages generally don't need planning permission provided the total area around the house covered by buildings is no more than 50% of the total land area excluding the house.
2. If a party wall agreement is needed, they should engage a party wall surveyor. They would protect both parties from unfair or misleading claims. Traditionally, both parties share a surveyor, but you are within your rights to demand your own at their cost.
3. Signing a party wall agreement does not take away your rights if the works result in damage to your property.

@ISthisOKatWork Always object to a party wall agreement. You then appoint your own party wall surveyor and they then work in your interests. Not your neighbours. Your neighbour has to pay.

Given the circumstances do make sure your Party Wall Surveyor is competent regarding retaining walls. Some won’t be. In your case, this is vital.

Some areas will require pp for a garage. Also for solar panels. Check with your Planning Authority web site.

Thank you both. I was hoping to sign the agreement to keep things friendly but I just can't see how I can prove any issues are due to the building work if no surveyor has been involved prior to the start of the project and in light of TizerorFizz's response I think I'm going to have to dissent.

As @TizerorFizz said it always helps to get your own surveyor for party wall issues. Don't be pressured into accepting a joint surveyor.

@ISthisOKatWork It’s perfectly ok to dissent and not unfriendly. It’s important to make sure your property is not affected. You need a PW surveyor looking after your interests. Is the retaining wall being rebuilt?

The party wall shouldn't need to be knocked down, but the wall is leaky and looks cracked so I am concerned that it will end up having to be demolished.
The original email said 'a new concrete floor will be laud with footings dug' but the party wall notice simply says 'lay a new concrete base and dig foundations for the West, South and East facing walls'.
I might be being OTT, which is why I am hesitant, but I feel there is potential for them to discover issues once work begins and I would hope that by getting a surveyor involved at the outset, that things can be managed better with less risk.

If it is a true party wall IE straddling the boundary, and the new garage is using it PP will be required. Permitted development only relates to development within the boundaries of a property. If it is crossing the boundary, PP will be required.

It's not a true party wall, the houses are detached and the garage wall is up to the boundary I believe. My house is approximately a metre from the garage.

@ISthisOKatWork Where are the foundations going? They might affect your property. Will any building work affect your property? 1m is definitely close. So get your own surveyor. You can also look at working hours, reinstatement, and access. Do they want to come on to your property? All worth considering.

Agree with all this but would add that in some areas you might want a local structural engineer to do the checks (eg London clay areas with extensive experience of shrinkage).

Either way, the neighbour should cover the costs of your report as well as their own if separate.

Thanks all, I am 'objecting' and asking for my own surveyor. I am definitely erring on the side of caution and I really hope it doesn't alienate them - I've been friendly and honest about it. To be honest, surely getting a condition report protects them as well. Thank you so much for all the advice - it's very difficult when you're not an expert in all these things to read up in the allotted two weeks on top of working and childcare.

I hope it works out for you. We were in a similar position - neighbour wanted to knock down an outbuilding, the wall of which formed the boundary with our garden. It started to get a bit fraught as he wanted to put up a new building and no fence but we objected and pointed out to him that it was a party wall. He ended up rebuilding a wall at his own cost to form the boundary which was a relief.

@ISthisOKatWork I would ask to see the drawings for the retaining wall too and ask a structural engineer to check them. The PW surveyor won’t be an expert in this.

Thank you.
Honestly, how do people muddle through all of this without the kindness of strangers. It seems like a vast area to read up on with lots of nuances which are difficult for a lay person to navigate.