Reducing the noise from neighbors dog by constructing wall?

I'm trying to figure out where this wall is going. Inside your house? Into the common space? Somewhere else?

Since the open space is shared, you may need to get permission to erect the wall, or at least have a survey done in order to be sure you aren't encroaching on their property.

Also, have you tried calling the town where you live? There are noise ordinances pretty much everywhere. You have already talked to them (and yes, I know that telling the town isn't going to win you a friendship with them, but that already seems to be shot) to no avail. A wall is all well and good but you're right to be concerned that it might not do the trick. You might want to handle at least a part of the problem from the dog side of things.

Wow, what overkill. You are going to build a 9' wall rather than taking other remedies like calling the city on your neighbor? Heck, they make devices that emit high pitched feedback (higher than people can hear) whenever it detects a bark. Have you thought of putting one of those on your side of the fence? It just seems like building a huge wall is an extreme reaction.

I agree with both comments - I'd go to the city - usually there are laws/rules against constant/excessive noise or for a cheaper solution (only $80 on this website) than a large wall...

http://www.ultimatebarkcontrol.com/a/bark-control/?pk_campaign=Adwords-Bark-USA-ENG&pk_kwd=dog%20barking&gclid=CISD-NvE87ACFQff4AodSxZVhA

Or you could you spray the dog with a hose each time he barks or if you are really cruel - give him a shot of pepper spray.

Most areas have codes for how high you can build a wall. What I am used to is 6 ft., only being able to surmount that in special cases for which you have to seek permission - or the city can order it removed.

I think even at nine it won't baffle the noise all that much.
Past that, if you are planning on adding five feet in wall height to your existing four, I am betting your present wall foundation isn't designed to take that addition.

Call the city.

I'd suggest building it around the dog. That would stop the barking ... eventually. Although I hear that doesn't work with cats.

Cats bark?

No, but they cat-ter-wall a bit!

I love low humor (you know, cows telling jokes).

That's how I always knew, yanno, what's a metaphor.