I have an existing concrete sidewalk that has seen better days. The wife wants a paver walk put in. Is it easy enough to just layout borders and level with base sand and then proceed to install pavers over top of existing concrete walk? Or do I need to rent a jackhammer and remove it first? The extra height would actually help due to drainage issues on the property.
If the sidewalk is level I see no need to remove it. You will need to run some sort of header board, steel edging or something to contain the sand though. You will want to use a decent thickness paver.
For a sidewalk, a 60 mm paver would work, but 80 mm pavers are more commonly available. The 100 mm pavers are usually used on heavy duty installations like airport taxiways and ship unloading facilities. The edge restraint (plastic. steel or aluminum) is necessary.
Since it is just a sidewalk, you can get away with putting the pavers over the concrete slab, but you should have a 1" sand setting bed (uniform and leveled not compacted). Then set the pavers (tight if you are using interlocking concrete pavers). Spread a thin layer of sand over the pavers and vibrate the sand into the joints, level the surface and vibrate the sand into the joints to get a tight interlock. Vibratory plate vibrators are available for rental.
If you are building a driveway or street you will have to get rid of the concrete slab and replace it with a compacted base. I you are considering clay pavers or the larger concrete "stepping stones" (over 10" in width or length), forget about the previous suggestions.