Concrete for deck post

[Steve K]

I recently discovered a rotted 6x6 on the corner of my deck. The post is rotted at the soil line and is free floating. When I replace the post should I pour concrete or just secure it in dirt? I've heard conflicting statements about concrete causing the pressure treated wood to rot faster. I also have two other post on their way with some rot but only about an inch so far. I was thinking about laminating a 6x6 next to them for support. Is there an easier and better way?
Thanks

 

[SupportTheSecond]

Personally I like the foam concrete substitute. Stronger and easier to work with for the most part.

 

[John_M52]

If you can get under it pour a concrete footing and use a teco type fastener on the top of the footing so the pressure treated isn't buried or in direct ground contact.

Alternately, I've read you can put gravel in the hole with the end of the post in gravel and then pour concrete around it so moisture can drain - but I've never done this and I'm not sure if it acts the same as a poured footing for load bearing.

 

[John_M52]

like this

https://www.homedepot.com/p/Simpson...-Base-for-6x6-Nominal-Lumber-ABA66Z/100375370

 

[Nevada Ed]

Being a retired Ironworker............ I don't like wood and have put up miles of chain link fense with Galvi , zinc coated post that are still standing, to this day.

Just a 2nd option to think about........ and they will not "Rot" with a little cement, around them !!

A little gravel at the bottom of the hole is a good idea, also.

Note;
When working in the field, we had less clean up while making cement by adding
the water, sand, the gravel and when mixed, the whole bag of cement to the mix.
No riped paper to clean up, is a good thing and it adds body to the mix.

 

[Pisgah]

Personally I like the foam concrete substitute. Stronger and easier to work with for the most part.

Love this stuff. First job I did with it could have gone smoother, but was a success; on the second job, no hitches (a little experience=BIG help!) and great results.

 

[Bald1]

Up here in western ny where weather plays hell with everything we use concrete. 42” hole concrete to top. PT post will not rot in concrete. At least not in our lifetime. If your real concerned about it rubberized automobile undercoating or black top crack filler on post where it contacts ground is extra protection

 

[crstrode]

The best way to secure a post is without concrete, the native soil being tamped and pounded in such that it is denser than the surrounding ground. Concrete around the post will always allow water to collect around the wood post. Even pressure treated posts will rot relatively quickly in the right conditions, and with concrete around the post it will happen quicker. I have been digging post holes and planting posts for fences, foundations, pole buildings etc for many MANY years. I started when Eisenhower was still President.

All that being said, in the past 5 years or so I have begun using a single bag of original high-strength Sakrete concrete mix when setting posts. The one and only reason is ease. These 70-year old arthritic joints don't do as well as they used to when tamping posts into place. Any post I place today will still be solid by the time I croak.

 

[arjay]

I’d paint the bottom and sides of the post with liquid tar where it contacts the concrete and put several inches of pea gravel under it before you pour.

 

[jeffrefrig]

I had to get a permit for my deck. (Danged neighbor down the street!) I had 4 holes to dig, as stated above 42" and those 12" cardboard tubes filled with concrete, 6x6 PT posts sitting atop the concrete with those galvanized 6x6" things anchoring the posts down. It has lasted 14 years now, no rot. Selling the house in upcoming future so now I don't care if they rot next year. We need permits for everything, and inspectors are so darned honest!

 

[robvious]

pour concrete above grade using the form tubes and attach with galvanized bracket.. they can be had in black iron if that is a preferred look... lots of options but wood & concrete don't play well together... wood & soil is worse

 

[Farmer17]

I've been in the construction business for 40 years and would never put wood inside a hole with concrete. I've seen it rot out the post dozens of times and is not an approved method by any engineer that I know. Like others have said use concrete in the footing then a galvanized steel Simpson post support or something similar and attached your post on top of it.

 

[coltle6920]

Biggest mistake people make when installing decks or even wooden fences is putting the post flush with the ground. Doesn't matter if it's embedded in concrete or dirt. Apparently they prefer the aesthetics of not seeing that cardboard tube over long lasting construction.

I've been watching a good show on TV called "Decked Out". It is filmed in Canada and highlights the building of custom decks for homeowners. Episodes can be watched on YouTube.

As the build begins you will see the various ways the deck can be secured to the ground. Usually it's the 4' hole with cardboard tube and cement poured inside. The cement is finished with a domed top for water runoff and a metal plate is placed on top to secure the wooden post. Metal rods have also been used instead of concrete for decks that don't carry much weight and are low to the ground.

Those cardboard tubes come in different lengths. Personally I prefer the deck post being higher up off the ground. You always place some shrubbery around it.