We have a pool in our back yard with a ten foot concrete decking sourrounding it. We would like to extend a wood or simulated wood decking an additional 20 feet over an area that slopes down the side of a hill. The slope drops approx. 1:1 and I'm trying to figure out what type of footing I need to install and how deep I may need to go for a stable foundation.

Where do you live and do you know your frost depth? By a slope of 1:1 are you meaning the hill is a 45 degree angle? That's pretty steep.

I live in Woodland Hills (Southern California) and have no idea what my frost depth is. Where we are, frost is not a concern, unless the morning glories freeze. As to the slope, yes, it's almost a 45 degree, which is why I am concerned that the cement footers sold at Home Depot are not the right way to go.

Thanks for your inquiry.

I would not use precast footers on a 45 slope. They could slip/slide with erosion. Dig a hole 12-16 in. wide that gets a bit wider as you go down. Dig at least 3 ft. down and fill with concrete. Install a steel pin in the concrete sticking straight up for later connection to your support. You can buy a ready-made plastic form that looks like an upside down spot light. Drop it in the hole and fill. I am going to stop at this point because CA has some pretty stiff building codes, for good reasons. You need to get a permit from your local building department and they can tell you additional details of requirements to avoid slippage and earth quake damage. DO NOT BUILD without the permit.