I am installing a patio in my back yard and want to know how I put the expansion joints on existing contrete. Do I need to glue them on, or buy something else, or what?

Thanks.

Expansion joints are normally only needed between two concrete slabs or at an edge of a slab where it's going to be against another structure, like a block wall or the house and won't be able to expand without buckling. You can buy the expansion material at just about any hardware store. It's usually a felt-like material or celotex. Just set it along the edge where you want it and pour the new concrete right up to it.

If the material you are installing the patio against is the houses' concrete slab or stem-wall. I'd suggest using felt paper as a bond breaker. If it is Brick I'd suggest using a 1/4" expansion Joint to you can caulk seal the two materials together. Install some No' 4 size dowels or bigger. I'd say every 16" apart, at least two inches below the surface to ensure the reinforcing doesn't expand due to freezing. You can use the dowels to hold the bond breaker. Remember when pouring concrete that a nice firm subsoil compacted and clean of organic material will ensure the life of your patio. Try to water cure the slab after your done pouring. Mist the surface of the slab on and off for about 7 days when you notice the Finished surface hardening. Then cure the concrete with thompsons water seal or another product similar in nature.

You Can Use 3/4 Pressure Treated 1x4 Or They Make A Fiber Board To Do This Also. Ive Never Nailed Either Of Them, The Slabs Put Enough Pressure On It To Keep It In Place