6x6 posts to uneven concrete footing

[soparklion11]

So my brother's deck wasn't near to meeting code. So I dug footings to code (40" below grade, 26x26") and told him to pour 13" of concrete with L- bolts where we wanted to place the posts so that we could attach via galvanized mounting brackets.

However, the surface of the concrete is not level, smooth, even, flat... really none of those terms apply. It's off by at least 1/4 inch across the span of 6 inches.

What do I do? Shim with wood? Coat with level concrete?

Brackets

 

[Sparky617]

I would put a Sona-tube on top of your 13" thick footing and bring the footing up to above the surface of the ground with concrete. I'd install a post bracket on top using a L-bolt embedded into the footing and go from there. Reason being, your posts will rot faster in the ground than above it. Not embedding it in the footing is a good idea, but an even better idea is to get it above grade.

My builder poured concrete around my posts, and my neighbors posts. I helped him repair his posts last year and I know I need to do mine soon. Water gets between the post and the concrete and just sits there, rotting out the SYP PT 6x6 post.

 

[Jeff Handy]

Sparky had a great idea there.

Just one more suggestion.

Maybe drill one or two holes in the center of each existing footing, and anchor in some long galvanized bolts, sticking out at least a few inches.
Or some thick threaded rod, or just rebar with epoxy in the cleaned out drill holes.

To help bond the base of the new footings extensions from frost heave, etc.

 

[soparklion11]

I would put a Sona-tube on top of your 13" thick footing and bring the footing up to above the surface of the ground with concrete. I'd install a post bracket on top using a L-bolt embedded into the footing and go from there. Reason being, your posts will rot faster in the ground than above it. Not embedding it in the footing is a good idea, but an even better idea is to get it above grade.

My builder poured concrete around my posts, and my neighbors posts. I helped him repair his posts last year and I know I need to do mine soon. Water gets between the post and the concrete and just sits there, rotting out the SYP PT 6x6 post.

I appreciate your input.

Post saver has a product that seals out water and oxygen over the ~10" from 2" above to 8" below surface level. The idea being that you have to have sufficient oxygen for rot.

Sparky had a great idea there.

Just one more suggestion.

Maybe drill one or two holes in the center of each existing footing, and anchor in some long galvanized bolts, sticking out at least a few inches.
Or some thick threaded rod, or just rebar with epoxy in the cleaned out drill holes.

To help bond the base of the new footings extensions from frost heave, etc.

What do you think of the Brackets that I have in the Simpson Strong-Tie galvanized 'Brackets' link at the bottom of the post? The more holes I put in the pressure treated lumber, the more entry points for water and rot...

 

[Jeff Handy]

Don’t bury the posts, then holes drilled in the posts will not rot.

The best “post saver” is being above ground level.

You can also get heavily treated posts, like used for a wood foundation.

But footing extensions are keeping everything high and dry.

 

[Jeff Handy]

Look up UC4C pressure treated wood.

 

[nealtw]

You are right about wood underground will not rot, But consider where it comes out of the ground where you have moisture and air, that is where they rot. You are not building a fence.

 

[bud16415]

I also take into account the height of the deck and lateral loads and stability. A deeply buried post in compacted soil will offer some lateral stability. The higher the deck and if it is attached to the house play a part.



If you are in a frost zone and the house is deeply anchored into footings well below the frost depth and you attach the deck to the house with a ledger then the outside posts or footing must be stabilized against frost also. If the deck is free standing IMO this is a lot less necessary. Where we live the frost depth can go as deep as 4’. My home is circa 1870s and the ledger method for my hot tub deck left a lot of questions as the deck load was high and the attachment to that old structure was iffy. I went free standing and floating the deck was only 30” high at its tallest corner and I set the whole deck on 12 pre-cast pads that I buried so my PT wood was just above grade. When the ground freezes everything is locked in solid and if a little freeze lift happens it raises or lowers the deck a little. The deck got a lot of diagonal cross bracing and has now been thru 5 winters a couple really bad and a couple freeze thaws winters and has held up great.

I would caution against doing this next to new construction that the back fill hasn’t had time to really compact but then again new construction should have no problem attaching to the house.

 

[soparklion11]

I also take into account the height of the deck and lateral loads and stability. A deeply buried post in compacted soil will offer some lateral stability. The higher the deck and if it is attached to the house play a part.

I also like the stability of the buried post, I plan to pack the 26" from the top of the footing to ground level in gravel.

Thank you EVERYONE! Be safe.