Advice on planning permission for neighbours flat downstairs.

[LetMeBe]

Hoping I can get some advice and suggestions that I may not have considered as this is our first property we have owned.
DH and I live in a large house converted into two flats, we live in the flat upstairs and are joint freeholders with the flat owner downstairs. We own our lease and the down stairs flat is rented out to a lovely family.

The owner of the downstairs flat has informed us he is considering to extend his property. The area with the lines is where he would like to extend to the right and further into the garden.
There is a bedroom in our flat overlooking the long narrow side of the garden and also a larger bedroom overlooking the larger part of the garden.
My first thought was that this would be an eyesore especially from the smaller bedroom window.
Also, if there was a flat roof the property would not be as secure, anyone could climb onto roof and access our windows.

Property next door is also 2 flats converted within a house, so just thinking what implications would it have on the downstairs flat as their kitchen and living room window are on the other side of the fence. Owner is considering maybe flat roof as it would block less light for the ground flat next door.

What are your thoughts to this? Is there anything else we should consider? As my first instinct was to not be over the moon by it, and to also think is there really and need to extend seeing as flat is rented out. But need to think this through carefully as we are looking to sell within 5 years to buy bigger property.
We have a fairly good relationship with the flat owner downstairs and will be meeting with him soon to discuss this.

Please excuse my drawing, thought it would help explain the layout, as you can see there is a L shape garden, we do not have access to this.

Well, you are joint freeholders, so he most likely needs your permission (which I expect you "cannot reasonably withhold"). Check your paperwork.
It looks fairly reasonable to me- I can't imagine you will see the roof below your windows unless you lean out. The disruption and security aspects seem more salient, so he needs to come up with a plan to mitigate those.

To be honest this is a fairly standard extension to your type of property. If it was your entire house you would maybe want to do it to your downstairs anyway. Lots of my friends have done this and none has perceived it as ugly from their upstairs bedrooms as it visually can look nice with skylights , nor have they considered it makes their house less secure.

Possibly you could discuss a living roof for the new flat roof which would make it much prettier and similar to your current view?

Could you ask them to build in a roof terrace as part of the extension so you would get some benefit?

That was my first thought too. Push for a roof terrace with a French door from the little bedroom. It'll turn a minus into a plus and make your fiat more attractive when you come to sell. You'll now have outside space/ a garden.

Can you look at whether you could also extend by the same amount, and how you would use that space? You might negotiate that they have double footings, so you can build on top in the future. Or the terrace is a nice idea.

Do you currently have access to the garden?

Push for a roof terrace with a French door from the little bedroom.

Great idea.

Oooh yes- roof terrace is genius!!

Be aware if they are planning on skylights they might not be so keen on you having a roof terrace.

Thank you very much for your helpful replies. No we do not have access to the garden. Love the idea of the terrace, will mention to DH as would need to convert the window into a door which need to think about as that is the kids bedroom.
Skylights I had never thought about, again will mention to DH.

Maybe they can skylight the side return bit and green roof or sedum roof around it and then the main part they can make strong enough to be a terrace for you. That would be a wonderful compromise.

Love the idea of the terrace, will mention to DH as would need to convert the window into a door which need to think about as that is the kids bedroom.

Could get a duel mech tilt and open door - can usually 'lock' it into positon so that it only tilts without the key.
Heavy and mechanism prone to breaking in the two houses i've had with big tilt/open doors or windows though.

Check planning constraints in you borough with regards to the roof terrace.

We own a downstairs flat and have extended. Our initial plan was to use the flat roof as a terrace for our neighbours, but it was explicitly stipulated in the planning permission that the roof was not allowed to be used in this way.