[b]Set concrete slab over porch for addition to house[/b]

[zeppo4]

I am going to make a addition to the back of my house that will incase the old porch slab. The addition will be larger then the porch is, and therefore will have a footer around it. The porch slab is about 1.5" below the slab of my house. I am thinking of laying the concrete over the porch slab to raise it to the level of the house slab. Is this Ok being that the concrete over this slab will be about 1.5" thick. Should I treat the old concrete before this.
Thanks Jeff

[Rich]

You should probably look at some type of bonding agent before pouring. If you had another 1/2" I would suggest doing a concrete slurry which is better than most bonding agents - and less costly. And when you order concrete make sure it's a 3/8" pea gravel mix.