jumping fences?

i have three cats and a small jack russell puppy. we are looking to relocate. there is a duplex that we are looking at.... we like it very much. my concern is the backyard. they have got it all fixed up fancy with curvy sidewalk, rocks & bark.. there is no grass back there. its completely fenced, however.. this is a bit weird but our backyard is against another house (they also own it) so only on the sides is wooded fences thats about 6 foot tall. i know my cats love to be outside but i am worried about them jumping over the fences and going into the streets, i would be very sad if they got hit by a car and died. they have been indoor cats for most of their lives however... when we moved back home to help with my mom who has MS-- she lives out in the country and we let our cats roam outside, they were fine... and now we re moving in, i know they love to be outside, i'd hate to force them back inside.. but if thats the best option for their safety then i'd do it.. what do you think????

IMO they are a lot safer inside. But if you insist on them having outside time you have a few choices (all of them supervised time and not outside all the time):

1. Train them to be on a harness/leash - not a collar/leash.

2. Get a portable cat enclosure. They are like fine mesh and are easy to put up as a temporary outside enclosure.

3. Build a dog-like kennel that is completely enclosed - top fence. The fencing would have to be smaller so that the cats could not get thru.

If you use any of theses suggestions, you could put them in the enclosure for a few hours and then take them back inside for the nite, etc. You could even put a tree house in the enclosure if you have it so that the weather can't get to the treehouse.