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George Bokros
08-10-2017, 7:42 AM
Considering having a deck built. It is a bigger project than I want to tackle myself. One contractor is telling me that setting the support posts is best done by digging the post holes per local code (42" deep) pouring a concrete footing the set in the posts and back fill. He does not fill the entire hole encasing the post in concrete because they will rot faster if encased in concrete.

Thoughts......

Jerome Stanek
08-10-2017, 7:59 AM
That is the way we set posts for pole barns that way the frost here will not have something to grab and heave

John Lanciani
08-10-2017, 8:17 AM
Wood below grade is never a good idea. The concrete should be extended above grade and the wood post attached with the proper bracket. Look at these for an idea; http://www.bigfootsystems.com/index.htm

Al Launier
08-10-2017, 8:19 AM
A concrete pier that extends below the frost line is necessary to prevent upheaval from frost. Further I prefer to use galvanized metal post supports by Simpson Strong-Tie, or similar, sitting on top of the concrete pier above ground rather than immerse the posts into the concrete with rot developing with time. Having the post (pressure treated) ends above grade & exposed to the air will prevent the posts rotting in the concrete.

Mel Fulks
08-10-2017, 11:58 AM
Just a few days ago I heard that pressure treated posts are not allowed in ground anymore. Have not looked for details .

Peter Christensen
08-10-2017, 1:08 PM
Around here the go to seems to be screw piles / helical piers because of the soil and frost. They are quick and have various post holders that fit the top of the pile. If they are available in your area you should look into them.

John K Jordan
08-10-2017, 1:09 PM
Considering having a deck built. It is a bigger project than I want to tackle myself. One contractor is telling me that setting the support posts is best done by digging the post holes per local code (42" deep) pouring a concrete footing the set in the posts and back fill. He does not fill the entire hole encasing the post in concrete because they will rot faster if encased in concrete.

I've been told at posts that get wet will sometimes rot more quickly if set in a pocket of continuous concrete under and up the sides of the posts. Water will evidently move down the post and get trapped at the bottom. I don't know if this is true since I've never excavated and inspected one set that way.

What I do is drill the hole and make what we've always called a concrete "punch pad" at the bottom of the hole. Then I put a little gravel on top, set the post on the gravel, then fill with gravel, soil, concrete, or some combination. The theory is any water that moves down the post will have a way to drain. When the post will be in the dry as building support, I'll fill the upper part of the hole around the post with concrete when pouring the floor, tying the post to the rebar in the floor.

Another way I've built decks is drill a hole well below frost line and make a pier with concrete and rebar, formed to put it about 4" above ground. Set the post directly on top of the flat pier, held in place with a length of rebar set into a hole drilled into the concrete and into the bottom of the post. I built a 7-level 1000 sq ft deck this way using 4/6 PT posts and it's been fine for 40 years now. I was not concerned that wind would lift this deck due to the way it was tied to the house overhead and the location. The building inspector was happy with the construction, joked about sending some contractors by for deck-building lessons. Ha.

I've also backfilled the holes but still with the post resting on a concrete pad below the frost line.

Regardless, you might check the code and with the building inspector in your area.

JKJ

Marc Jeske
08-10-2017, 5:00 PM
You will get a myriad of various replies on this question.

In MY opinion, My studies preparing to build a Pole Building... in or at ground level, use proper treated wood...CCA .80, not less, not .60, and you will be good.

The above is very proven.

Google it.

As far as the backfill, everyone has opinions, jury still seems to be out on that.

Yes, it would be better for wood longevity NOT to have any below grade, BUT there are other tradeoffs, mostly in layman terms like wind resistance, being a "hinge" point no matter how well you do it... Still a hinge point.


Using the new treated stuff because some 1/100,000,000 goofy kid will come and eat it like a Beaver, .. all bets are off.

The move from CCA is mostly BS.


Again, broken record here, study it yourself.

And read Tech articles, not what someones MawMaw's Cuzzin sed.

Marc

Lee Schierer
08-10-2017, 5:26 PM
One contractor is telling me that setting the support posts is best done by digging the post holes per local code (42" deep) pouring a concrete footing the set in the posts and back fill.

If your local code defines what is needed you would be wise to follow the code so you don't run into problems if code enforcement happens by. You might also want to check to see if a permit is required to build a deck.

Marc Jeske
08-10-2017, 5:34 PM
As Lee said.

Start from there, then.. IF you have options, study them.

Marc

Mel Fulks
08-10-2017, 5:41 PM
Just re read all and don't see any comment on ban on pressure treated posts in ground. Is that catching on in some places, or is that just a "green practice" suggestion? Thanks

Todd Mason-Darnell
08-10-2017, 6:32 PM
A concrete pier that extends below the frost line is necessary to prevent upheaval from frost. Further I prefer to use galvanized metal post supports by Simpson Strong-Tie, or similar, sitting on top of the concrete pier above ground rather than immerse the posts into the concrete with rot developing with time. Having the post (pressure treated) ends above grade & exposed to the air will prevent the posts rotting in the concrete.

+1 on this method. I have build several decks and outdoor structures using this method.

Lee Schierer
08-10-2017, 6:43 PM
Here is a design guide (http://www.awc.org/pdf/codes-standards/publications/dca/AWC-DCA62012-DeckGuide-1405.pdf) for decks that meet the 2012 building code. Note that local building codes can be more strict than the national code.

Sam Murdoch
08-10-2017, 8:09 PM
A tried and true method is to dig the hole below the frost line in your area, set a SONTUBE of the chosen dia. - 6" for a 4x4 post , 8" for a 6x6 post, fill with concrete so that the concrete is above grade a few inches to 6" (ideally all at a relative level height but that it nitpicking) then set a PT post on top of that using a Simpson Strong Tie post base -

365827

This will last 30 years or more without concern. Easy and effective and no question about that it works. The number of posts , the need for inter post bracing and how the deck is secured to the building are all variables based on height, sizing and calculated load. There are other systems for setting footings in soft ground that might need to be considered but the final result of a PT post sitting on concrete above ground is a good method.

Jerome Stanek
08-11-2017, 7:47 AM
George go to the building department and get a copy of their requirements or ask the inspector what he wants. I always liked talking to the inspectors and asking them how they want something done this is when I traveled around to install Revco drugs stores. Most of the time they were very helpful and easier to deal with

Allan Dozier
08-11-2017, 8:36 AM
As Marc said, wood beneath the ground is fine depending on the treatment. If you have trouble finding what you need, contact some dock building companies and ask where they get their wood. https://sites.google.com/site/alexinaofshoreham/IMG_4234-large.JPG

Rich Engelhardt
08-11-2017, 10:06 AM
George,
I've heard through he contractor grape vine that:

A tried and true method is to dig the hole below the frost line in your area, set a SONTUBE of the chosen dia. - 6" for a 4x4 post , 8" for a 6x6 post, fill with concrete so that the concrete is above grade a few inches to 6" (ideally all at a relative level height but that it nitpicking) then set a PT post on top of that using a Simpson Strong Tie post base -What Sam says is code now in most cities in NE Ohio.
The local building department (as mentioned) can give you the right answer.

George Bokros
08-11-2017, 1:24 PM
George,
I've heard through he contractor grape vine that:
What Sam says is code now in most cities in NE Ohio.
The local building department (as mentioned) can give you the right answer.

Thanks Rich. The contractor stated that Streetsboro requires the footing to be 42" deep where most cites accept 38" deep so I assume he is familiar with the local code but I am going to make the call anyway.

Allan Dozier
08-11-2017, 2:44 PM
Yes, best advice is check with your building standards department. When they were building the deck on my shop last month the 6X6 posts failed inspection. They had to go back and pour footings for each post 16" X 16" and 8" thick to meet code.

Sam Murdoch
08-11-2017, 3:16 PM
Yes, best advice is check with your building standards department. When they were building the deck on my shop last month the 6X6 posts failed inspection. They had to go back and pour footings for each post 16" X 16" and 8" thick to meet code.

Somebody in that department has a relative in the concrete business :(. Was your shop deck BIG and off the ground 8+ feet? In a flood plain?
It's what it is but sure seems excessive.

Brian Kent
08-11-2017, 4:59 PM
I am replacing my fence today. Treated posts in concrete 18" deep. All but the top 3-4" is entirely rotted away. They are only 7 years old in a very mild climate. I am using Simpson galvanized Standoff Post bases.

John K Jordan
08-11-2017, 5:45 PM
I am replacing my fence today. Treated posts in concrete 18" deep. All but the top 3-4" is entirely rotted away. They are only 7 years old in a very mild climate. I am using Simpson galvanized Standoff Post bases.

Yikes. That would explain the wobblies!

Hey, are the Simpson bases strong enough to resist side loads on the fence? I was afraid they might bend and allow the fence to tilt, perhaps from high wind loads. I've never used them.

JKJ

Brian Kent
08-11-2017, 6:18 PM
The ones I am using are through Home Depot: I add a 1/2" x 6" bolt through the bottom, with a washer and nut against the bottom. I use a couple of galvanized 1/2 bolts through the fence post, and there are holes for additional nails. I think they will be fine in the wind but I also don't live in hurricane or tornado country.

http://www.homedepot.com/p/Simpson-Strong-Tie-PBS-4-in-x-4-in-ZMAX-Galvanized-Standoff-Post-Base-PBS44AZ/100374846

Sam Murdoch
08-11-2017, 6:19 PM
Not contributing to this discussion as I misunderstood the question.
Oh well...

David Helm
08-11-2017, 6:43 PM
In my forty year building career I have built hundreds of decks; to my knowledge, all still standing. In my location, frost depth is only 14 inches. For a deck at the first floor, no roof, code calls for a footing that is 12 X 12 x 18 inches deep. I would never pour a sonotube without a wider footing beneath it. All the commenters talking about stand off brackets are right on. Even the old CCA treated lumber would rot when under ground. The lumber is called ground contact, not under ground. As several people have said, check with your local code department for specifics for your area.

John K Jordan
08-11-2017, 7:53 PM
The ones I am using are through Home Depot: I add a 1/2" x 6" bolt through the bottom, with a washer and nut against the bottom. I use a couple of galvanized 1/2 bolts through the fence post, and there are holes for additional nails. I think they will be fine in the wind but I also don't live in hurricane or tornado country.

http://www.homedepot.com/p/Simpson-Strong-Tie-PBS-4-in-x-4-in-ZMAX-Galvanized-Standoff-Post-Base-PBS44AZ/100374846

The reason I asked about the side loads was because I always thought this type of post base was for structures where the posts were constrained from moving at the top like a deck, what Simpson calls "top-supported structures". Their web site states The PBS post base provides a connection between a post (or column) for decks, patio covers and other top-supported structures.

I found this about PBS on the Simpson web site and in their manual: Post bases do not provide adequate resistance to prevent members from rotating about the base and therefore are not recommended for non-top-supported installations (such as fences or unbraced carports).

http://embed.widencdn.net/pdf/plus/ssttoolbox/2c1fhtnuv8/C-C-2017-p098-099.pdf
https://www.strongtie.com/standoffpostbases_castinplacepostbases/pbs_base/p/pbs

It just seemed a shame if the brackets failed after all that work.

In their E-Z line Simpson does offer what they call an E-Z Base advertised to attach 4x4 fence posts to concrete. But even then they have this disclaimer about side loads: Notwithstanding the terms of the Limited Warranty, Simpson Strong-Tie does not guarantee, represent or warrant that this product will perform under, or prevent or reduce damage caused by corrosion, any seismic, wind, atmospheric, or other load-producing event.

https://www.strongtie.com/fences_decksandfences/ezproducts_productgroup_wcc/p/e-z-base.-e-z-mender.e-z-spike

I am not a structural engineer and am not trying to second guess your design. If there is any doubt, you might check with a fencing contractor or architect.

JKJ

Marc Jeske
08-11-2017, 8:13 PM
CCA treating has proven to last for longer than many think.. IF.. and only IF, the sufficient or higher concentration per the use.

Allen in post #16 started to explain this.


Even though CCA .6 or as low as .4 is most commonly used at and IN ground, history shows .80 (harder to find.. NOT at Big Box stores).. fares many many more years.

The stuff used by even like Governmental agencies for long term saltwater exposure
( the overall most attacked due to "Marine Borers", etc) is if I recall 2.5 , 4- 5 x the typical homeowner stuff.


In the pole shop we are building this summer, we are providing the .80 posts.

Contractor uses .60.

Best to try to source from a local "industrial" type of lumberyard, or ask a local Treating company for dealers.


And it also goes back to what is being discussed above, as I mentioned also, any method where the post does not go down substantially below grade will be a weak link in the chain.

It's only logical.

So then, in many cases will involve additional bracing and hassles.


I am NOT debating longevity of concrete vs wood in ground.. I DO believe the longest lasting overall will be NO wood in or close to grade.

But that also assumes properly formulated.. AND placed concrete in decent conditions, to give that long life.

NOT just Yahooo's pouring dry bags.


It all though comes down to if one is in an inspected area, choices are limited.

Some info in link below- See the Table at bottom of page.

Marc

http://www.ccaresearch.org/about_cca.htm

Marc Jeske
08-11-2017, 8:39 PM
For those interested in deeper info on this issue... Marc

http://www.americanpoleandtimber.com/wp-content/uploads/2015/06/treated_wood_specguide.pdf

Allan Dozier
08-11-2017, 8:43 PM
Somebody in that department has a relative in the concrete business :(. Was your shop deck BIG and off the ground 8+ feet? In a flood plain?
It's what it is but sure seems excessive.

You are probably on to something there Sam, good point. The deck is raised up above the basement, like a second floor deck. And it is also covered with a roof.

Brian Kent
08-11-2017, 11:53 PM
Thank you for the info, John. They are all in the ground now. Glad this is not tornado country!