I think it is 6ft but you best check in your area but less is best or not at all.

There are much nicer hedges than Laylandi,hope you dont mind me saying this.

I agree Scotscat

You'll find that once they get much over that height they become much more difficult to trim and maintain, and more expensive to get someone to trim back huge ones too.

6 foot if it is a hedge dividing 2 gardens

half inch hopefully lol .

Yep! 6ft. We got rid of our's as they got too big to handle and they were blocking all the light in our Neighbours gardens.One of my neighbours has one in their garden and it is getting too big and would love him to cut it down as it is hanging over my side, Oh! Dear I don't want to fall out over this with him by asking him to give it a good trim, so think first about a Laylandi. If it gets too big it will cost a lot to have it cut down if it got BIG. Oooo! Errrr!

lady essex your within your rights to cut of any overhang from his tree and offer him the trimmings.this is the legal way of doing it.it mite be worth aproaching him in a friendly manner though and seeing what he sais.