Lumber rated for subterranean use?

[nemesis]

I'm going to build a freestanding deck in my back yard. It's going to be 10'X16' about 3" to 10" above the ground. On a mild slope.

I'm considering the options and had settled on concrete piers with brackets to hold the beams. Etc.

But I'm seeing ads and boobtube videos of experienced builders using treated lumber rated for ground contact/below ground use. Below ground use necessitates a gravel base, post and concrete in the hole.

Have they come that far? Because, back in the day, treated lumber was seriously only good for insects. It didn't stop rot. And you didn't put it below ground for anything other than fence posts or a basketball goal.

What say ye? Is it good for a small freestanding backyard deck?

Thanks.

 

[Catt57]

Treated lumber will certainly last longer in ground contact than untreated will. Keeping it off the ground it will last even longer.

Current pressure treated lumber is not only insect resistant but also much more moisture resistant than it used to be in decades past.

 

[TwoForFlinching]

Ground contact will serve you good for a decade or so. Pour your concrete, use brackets and treated wood. It'll last decades.

Pro-Tip: Buy your treated lumber and let it sit and dry for a few weeks. Try to pick straight grain lumber. Look at the end, if it's curved, hard pass. If it contains the pith, hide it in the back of the stack so some poor schmuck doesn't end up with it. Stack it with spacers, it'll dry straight as possible, be lighter and easier to machine.

 

[Parks 788]

No. I would not use that method for a deck. If building a property line fence or similar then yes. For a patio/deck application that you probably want to last 10-20 years then, no. Dependent on slope and size of deck I' spend the extra money and use smaller 24" long X 8" diameter sonotubes and put brackets on top for your beams.

Similar to this but on a much smaller scale. I like spending other peoples money.

If you are going to stick with something on the less expensive side and quicker build aspect I'd look at using this bagged foam in place of using concrete in the post holes. OUr neighbor used it and it was pretty slick and probably has no water transfer into the wood compared to concrete. Pull up some vids. Easy stuff to use.
https://www.homedepot.com/p/Sika-33-fl-oz-Fence-Post-Mix-7116170/300934597

 

[HiredHand]

Ground screws may also be an option for you.

 

[Snattlerake]

What about the grass under the deck?

 

[TwoForFlinching]

What about the grass under the deck?

If it's bermuda, it'll die off in the shade. Round Up everything else, sit back, and wait for that Bayer/Monsanto settlement check.

 

[Snattlerake]

It's a mix of fescue and bermuda and switchgrass and weeds. You know Oklahoma grass.

 

[nemesis]

What about the grass under the deck?

8 or 10 mil poly covered with gravel.

 

[beardking]

No. I would not use that method for a deck. If building a property line fence or similar then yes. For a patio/deck application that you probably want to last 10-20 years then, no. Dependent on slope and size of deck I' spend the extra money and use smaller 24" long X 8" diameter sonotubes and put brackets on top for your beams.

Similar to this but on a much smaller scale. I like spending other peoples money.
View attachment 167895


If you are going to stick with something on the less expensive side and quicker build aspect I'd look at using this bagged foam in place of using concrete in the post holes. OUr neighbor used it and it was pretty slick and probably has no water transfer into the wood compared to concrete. Pull up some vids. Easy stuff to use.
https://www.homedepot.com/p/Sika-33-fl-oz-Fence-Post-Mix-7116170/300934597

I know it's just one video, but after seeing this I personally would shy away from using that stuff.