Hi,
I’m in the middle of completing the “How to Perform Deck Inspections” course. There are several images showing posts in contact with grade. At one point the material advises burying the post 12 inches below grade to prevent lateral movement…
"The lateral restraint may be provided by a minimum post-to-footing connection based on the manufacturer’s requirements for connections supplying lateral restraint, or by embedding the post at least 12 inches into the soil or concrete piers. "
When I google “are deck posts permitted to be in contact with soil?” Google clearly states that deck posts (treated or untreated are not to be in contact with soil.
Great demonstration of how smart AI isn’t. You do realize that piers that support docks are in direct contact with water! The entire city of Venice is supported by wood posts! Point is there are all different levels of wood treatment. Ground (soil) contact is not even the most extreme. AWPA Wood Treatment.pdf (35.0 KB)
I dont see a ton of decks in FL, but almost every time I do, they are in direct contact.
I will probe down a little, and if they are in good shape, I dont call it out.
They can last 30 years like that if its treated
It’s allowed, just not a great idea in my area. I have found many, many rotted deck posts by sticking a long screwdriver down into the posts under the soil.
When you’re picking up a 2x6x8 and it weighs 45lbs, you’ve got a good one. Just bring your shitty clothes because they’re going to get a dousing of chemicals.
Right, which is why on the few ground contact decks I’ve seen, as long as they aren’t rotted away and chock-a-block with termites, I am mute on the subject.
As Sam Kineson used to say “You know what this is? This is Sand. Nothing grows in this shit. You what it’s going to be in 100 years? IT’S GOING TO BE SAND!”
I always document wood buried in ground for decks.
Here locally in my area, there are certain municipalities and AHJ’s that will not allow wood to ground contact for decks. So, when reporting a concern or a defect on an inspection, you do not have to cite or source code. Sometimes is just a common sense thing. And FWIW, be careful using those AI bot thingy’s on the web
Evening, Justin. Hope this form post, Lol, finds you well…
Besides post soil contact, lets go deeper…
IRC 2021: Deck.
Footings: Deck posts must be supported by concrete footings designed to handle all loads.
Footing Depth: Footings need to be placed at least 12 inches (305 mm) *below the undisturbed ground surface.
Ground Clearance: The walking surface of the deck should not be more than 20 inches (508 mm) above the ground at any point within 36 inches (914 mm) of the deck’s edge.
Post Restraint: Deck posts must be secured to prevent them from shifting or tilting. This can be achieved by embedding the post in concrete or soil, or by using approved connectors.
I see only 1 occurrence where posts are below grade. Treated posts with a footing and attached footing - post support berried below grade. 3rd illustration to the right. That should give a home inspector plenty of room to deduce at least 75% of the deck post they run into during an inspection.
Thank you all for your excellent responses to my question. This forum is such an incredible resource.
Here are some of my take-aways…
While wood treatments UC-4A, 4B and 4C are designed for ground contact unless the inspection is for new construction there is no way for me to know at the time of the inspection what grade was used.
Local conditions play a big part. I live in CT where termites are an issue. We have sandy loam soil that usually drains well however.
All deck posts should be on footings. I see many decks with posts missing footings resting on the ground and will call it out.
My main take-away (for now) is if i see a wood post on grade I’ll do a spike test for rot or WDI destruction. If rot or WDI is present I’ll call it out, otherwise I’ll move on.
yes…I set my deck posts on a concrete footing surrounded by concrete and it still is as strong and looks the same as it did 32 years ago. Now the new treated wood is not as good as the old stuff. As a precaution I recommend squirting some copper naphthenate at the post to ground junction point every so often and wherever else you think might need it.
I just wanted to add that pylons for beach houses are frequently just pressure treated wood poles. As well as utility poles. Both are buried in the the ground.
