Thanks for your enquiry.
As is the norm, I'm afraid that from what you have told me, the roof space does not belong to you and the Freeholder is correct.
When assessing if the roof space does belong to your Flat, you have to study the definition of the "Flat" in the Lease and any accompanying Plan. Only those items mentioned in the definition and the Plan belong to you.
As the definition of your Flat does not mention the roof space (it says " the first floor building", and does not mention any roof space) and I am guessing the Plan does not show the roof space edged in red, then you have not been granted a Lease of the roof space.
I am sorry this is not the answer you were looking for, but sets out the legal position.
If I have assisted, I would be grateful if you could leave positive feedback.
Even the ceiling is not mentioned, does that mean that he owns my ceiling?
Am I eligible to buy a share of the freehold?
Is there any standard way to determine how much it would be a reasonable price to pay?
The inner surface of your ceiling would be classed as yours,but anything above this is classed as being outside your Flat and hence belongs to the Freeholder.
I obviously don't know the history as to why the Freehold belongs solely to downstairs (usually, the Freehold would be owned jointly between both Flats), but I'm afraid that under legislation, you are not entitled to purchase a share or the whole of the Freehold.
You can always ask the Freeholder if they would be willing to sell you a half share- the cost would depend on the value of the Flats and how many years are left on your Lease but the average price for half the Freehold is between £8,000 and £10,000.
I'm sorry I can not give you better news.
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