Good day all sifus and gurus, a newbie question here.
As per title, I've seen plenty of single storey owners spending lots of money to do floor extension renovations. (1 storey -> 2 storey)
I'm curious if this actually increase the valuation of the house?
If not aren't these people risking the bulk of the money spent having zero returns when selling?

if the renovation / extension is legal and approved by local MP, of course it contributes into the valuation.

Most owners do it for their own preferences especially if they are staying in it, not so much to increase the value. Valuation is useless if potential buyer do not like extension

Increase floor space with LA approval, yes.

Others, no.

Valuation Exec here, the value for the owner is only more rooms to rent.

But selling price, valuer will ignore the extension if it is illegal, will even consider extension to be -tive to value if big valuer also consider demolition cost.

If got proper approval documentation from planning department, then valuation will give +ve increase to value, jack up like 5-10%