You can always ask!
I think an issue, though, is that the price was probably agreed on the house "as is". It could sound cheeky, having agreed the price on the house "as is" to then come back and look for more money off because things that were probably reasonably obvious as needing doing, need doing.
The other way of looking at it is that, hey, its a buyers market, so ask away. Or, that the original offer was made before the survey which uncovered issues that had not bene anticipated.
So, as I said above, you can always ask!
mf