valuation for houses with planning permission on plot

secla

Im looking for a house locally that is on a larger than average plot.
A couple that have come up recently have got planning permission granted for an extra house which obviously increases the asking price. If i apply for a mortgage am i likely to get it down valued ? I am not really sure how much in real terms the planning permission adds to the value but i am assuming the mortgage valuations will only take into account what the plot and house would be worth and not any added value the planning permission adds.

Am i right or wrong ? 

K_S

@secla For a mainstream residential mortgage, I think you are right. Here's an excerpt from the Nationwide valuer's manual -

Properties having large gardens or adjoining building plots with “hope” or development” value must be valued excluding the potential benefit, as planning approvals are of limited duration. 

secla

yup thats as i thought by the looks of it
I also wouldnt be planning on building an extra house on the land so i guess id have to find any extra value myself and then instantly lose it once the planning lapsed