Extending a slab

[carvin_brown]

I am a new homeowner and my house came with a 10'x10' slab in the back of my house. It is attached. I would like to extend it to a 10'x25' slab, an additional 10'x15'. My questions are:

1. How deep should I go? 3" or 4"

2. Do I have to put one of those black things between the old slab and the new slab? What is that thing called anyway?

3. Do I pour it right against the foundation?

4. I plan to make a screened in patio 10'x25', do you have anymore recommendations?

If climate is a factor, I live in St. Augustine, Fl.

[Rich]

Answers following:
1. 4"

2. It's a good idea to put the "fiber expansion joint filler" between pours. There is also cork expansion joint fillers.

3. No - put the expansion joint filler in there first.

4. Possibly the only additional information for the concrete would be to thicken the edge of the slab just in case you need additional support for the future framing.

Hope that helps.