Footers

If and when the frozen tundra here in SE Pa. ever thaws I will build a small deck on the back of my house. Sub-zero temps make it almost impossible to dig holes for footers. Anyway, I have a question about making the holes for the footers when the time comes. I am planning to dig 6 of them 3 feet deep and 12" in diameter. I am not sure what is the proper method for doing them. Do I drop in about 6" of cement in the hole then put the 6 x 6 post on top of that when dry, or do I drop in cement and put the post into the wet cement and fill around it? Also, I have dug some holes for another project that I won't finish and when I got down to 3 feet deep I hit a solid piece of rock. I also dug some other holes (with a rented augur) at different places from the first hole and about 20 feet away and the same thing happened where I could go no farther than 3 feet deep. If that is some sort of rock shelf can I use that as the footer base? I'm sure as anything not going to be able to dig through it whatever it is. Thanks.

Rich

 

It is a lot better to fill the hole with concrete and use a bracket on the top to attach the post to. I doubt you will find many here that condone embedding a deck post in concrete.

 

Check your local authorities for the frost line requirements. It may be more than 3'. Dig it out to where you can insert a 12" sonotube in it, lay in some gravel in the bottom and fill with concrete. You can put your post base in now, or wait and drill it in after it cures. Take really good triangluation measurements to make sure you hit real close to the center of the footer with your post. You don't bury wood in concrete.

 

Thank you, Chandler. That info will be very helpful. I checked and the frost line is 36" in my area. Have a great day.

Rich

 

You definitely want to follow that recommendation! If you embed the posts in the concrete they will rot out no matter what type of wood you use. Pour the footers and raise them several inches above grade and then use a Simpson bracket to attach the posts to.

 

http://www.awc.org/publications/DCA/DCA6/DCA6-12.pdf

Per the above residential deck building code guidelines (pages 12 & 13), Your "FOOTER" is different than the pier that sits on the footer and what you attach your lumber to. I do mine in what is called a double pour. Dig the appropriate size hole (minimum shows 18" round hole but could be larger) and pour in a footer to the minimum thickness (again per table on page 12). Then, once cured, you can set your 12" sonotube on top and make your pier to support your lumber.

 

I probably should have used the term pier instead of footers but he will certainly get the idea of what I wrote.

 

I put rebar into the hole to tie the pier to the footer for added strength. I feel fortunate that I only have to go down 18", but set 24" as a minimum. Sorry for those who have to go even deeper.

The rebar serves multiple purposes. One to tie components together and 2 to set the depth using a transit so that everything comes out at the same height.

 

The need for a separate pier and footer varies from location to location depending on the soil conditions. Many areas don't require that and even in some that doyou can just widen the hole at the bottom so it has a bigger base. They also make special cone-shaped forms that you can attached to your sonotubes so you can put the entire thing at once.