I have recently been contacted by our local council who are proposing
to put an extension on the house next door (council owned). They are
asking us to sign a party wall consent form as the proposed extension
will fall on the boundary of our property. I have not seen any
evidence of planning applications so far so I have no idea how far
this proposed extension is from being built. We have owned the house
for seven years and the previous owners purchased under a
right-to-buy.

My main concern is that the extension is large, they have sent the
1:50 scale drawings and from this we have extrapolated it will be 11m
from the rear wall of the house to the end of the extension. So our
party wall will be 11m long and 2.8m high from ground level to the
eaves.

Just to add to this, they intend to have a pitched slate roof (in
keeping with the existing terrace) and the highest point of the pitch
will be 4.6m!

I am worried that the already dingy garden is going to to be plunged
into near darkness along with our kitchen and dining room.

Our garden is southwest facing, and this extension is going to be a
formidable boundary to the northwest side of the garden, putting the
whole of the corner immediately adjacent to our house into the shade
for much of the day.

We have good relations with our neighbours and the extension is for
the use of their disabled son (it is a bathroom and bedroom all with
level access). So we have no intention of refusing permission because
they have waited years for this to happen.

Do we have any recourse with the council (compensation) if we feel the
extension will devalue our property or affect our future ability to
sell the property? Who can determine this for us?

Any input gratefully received,
Jason.