Originally Posted by lachase
Our house is about 40 years old, built halfway down a hill, clay soil, water runs toward the house and are in a zone 5 location which has about a 48" frostline. We've had to put in measures for drainage and it has lots of issues. At the back of the house we have a double layered concrete patio. I noticed that the caulking has separate and the level seems a little lower from the house this year. We want to build a 12' X 24' covered porch over the existing patio, and I would like to know what is proper for making sure it is secure, doesn't shift, etc. We'd like to leave the slab if possible. I'd be grateful if someone could tell me the best way to approach this project. Thanks!
I'm in the process of building a shed roof over an existing concrete deck that is 24" above grade.
To support the roof and its snow load, I had to install piers below the deck foundation (48" in the ground). I had to put in footings (16X16X6) then make the piers using Sono tubes, to underpin the existing concrete foundation walls.
In your case you would have to cut open the existing concrete pad where you plan to locate the piers. Excavate down to the 48" mark and pour the footing. Install a SONO tube and backfill to hold it in place. Fill the tube with cement, and add the beam anchors.
The top of the excavation could be cemented back over if desired.