I think I'd use the new post supports that are available. You can pour a small concrete pad for each post and set the post support on it. Check at your local Home Depot or Lowes or independent building supply store.

Just another thought here is - how close are you to the water and what are the chances of high winds, flooding, or the effects of tropical storms?

When I lived in FL the sandy soil was often soaked due to heavy rains and the occasional tropical storm, and hurricanes. High winds would topple trees when the ground was soaked enough.

I live in Georgia now and I think this method is the best:

http://www.youtube.com/watch?v=MCa_87Dkw1M&feature=related

You wrote, "Just another thought here is - how close are you to the water and what are the chances of high winds, flooding, or the effects of tropical storms?"

100%

We have the same soil and weather conditions here, but unlike trees, a deck is not going to blow over unless it is really high off the ground. There are not so many two-story dwellings here.

MY friend just put up a deck in his home that is about 12 to 18" above ground. He tamped them in, but I will ask him.

I had friends in Lakeland who lived in a large old 2-story house in an area with a lot of older 2-story homes. Some have 2nd-story decks. The OP lives in the St. John's River area, which sounds like he'd be near Jacksonville. I'm not so familiar with that area.

The St John runs North from around Melbourne to Jacksonville. I live in the middle.
I live about 3/4 mile from the river in a building code 120 mph zone, and am not in a 100 year flood plan zone.
The deck will be almost ground level at the house, and 1-1/2' high on the outside edge. There is a grade of approximately 1' drop for 10' run away from the house so the posts will never sit in standing water. As AH stated, we get a lot of rain here so the deck will get wet about 200 days a year.
I do not believe a hurricane could uplift a deck that has 33" sunk and properly tamped posts. I DO believe a hurricane could uplift some of the other recommended construction methods, although there are some good recommendations here.

Just a quick question, have you discussed this with the zoning board?

Are there any other codes that you need to follow?

How much property do you have up there? From the pictures it looks like a nice sized yard.

Haven't discussed it with zoning. The deck is existing and dilapidated, I'm just replacing it.

I think there is a "deck construction code". I am good with tools and will follow construction norms, just fishing for post expertise/experience.

I have a little over 5 acres. If you're on the space coast, I'm due west 30 miles...as opposed to "up there".

How about concrete footers poured around steel posts.

Or footers with steel plates that bolt into the footer and accept 4x4 posts.

You will never equal the strength of concrete with dirt. Especially wet dirt.

Tie the corners together with steel stringers (maybe I-beams) and use those to support floor joists.

ur right. i missed ur post.

With a deck that big, I'd get a permit and go by the county code. I just had a friend get popped for putting a pool and deck in his back yard...............rural area. They're doing fly overs.

Even if you don't have to get a permit to replace existing, I'd go by code. It'll save you a nightmare inspection report if you ever try to sell the place.

.. l like your method of tamping the posts in below the frost line.. i need to set three locust posts for a grape arbor.. have you had problems with rot at ground level?. do you use the dirt that came out of the hole, or do you tamp them in with sand?. i'm thinking of using tamping material that will drain water away from the post. maybe limestone chips.

i watched an old timer set posts that had to hold the weight of a corn crib.. he dug the holes below the frost line.. 36" in my area,. then he tamped the bottom of the holes and dumped a few buckets of sand in.. he laid a large flat rock on the sand then he dump more sand in the hole until the rock was covered..,. he poured water in until the sand flowed around the rock.. the sand supported the rock and provided drainage too. he set the posts [locust] on the rock then tamped it in using the same dirt that came out of the hole minus any stones.

that was 45 yrs. ago.. i make a point of looking at the corn crib when i pass it.. it's still straight and level.

.. i'ld advize using locust instead of treated lumber. it will out last you and your grandchildren.

100,000 Dollar question:

Where is Florida?

Black locust posts are great, but not available everywhere. I'd pour concrete into Sonotubes set below the frost line and use galvanized steel post holders on top of the concrete. Pressure treated posts stand up well if they are above ground and not set into the concrete. Locust is better but optional.

I've heard stories about setting treated posts in concrete. They rot faster if you do that. That means that tamping is the way to go.

That said, I just had a pole barn built a few years ago. The builder offered vinyl 'post protectors' for the 5x5's. I expected them to be rather thin and flimsy, but in the clay soil on my lot, even treated lumber won't stay in the ground long without rotting so I purchased them anyway and was pleasantly surprised. They're better than 1/8" thick. They wrap completely around the end of the post and are bolted to the post with only one bolt that's above the ground surface. When complete, the posts should stay completely dry unless water gets in from the inside of the building.

The builder also drilled holes below the frost line and placed a pill shaped cinder block under the post. The blocks were cylindrical, about 8" high and 16" diameter. Each post was set on one of these 'pills'. I guess they served as a footer so no concrete pour was necessary. Then they tamped each post in as well.

I've been happy with the results. I've noticed no settling and as I said, with the posts wrapped in the vinyl they should last a good long time.

that's good advise.g.a from me.

could the pills be anti-insectide?

Nope. They just looked like the same material as a cinder block, loosely compressed aggregate with portland to hold them together. They were delivered on a pallet from a local brick & mason supplier.

I will never again set wood into aggregate or concrete...peroid! Mind you I live in a climate where it's snows for 7 months out of the year. Concrete and wood don't mix (pun intended!). Every kind of wood will rot eventually (pressure treated too!) because of the moisture in concrete. The rot is due to the repeated wetting/drying cycle. Usually happens right where the post enters the concrete. Same thing if it's buried in aggregate. It wouldn't rot if it was always wet and never exposed to air.

There's a company in British Columbia now salvaging 500 old old growth logs from the bottom of rivers left there by loggers. The stuff is pristine after you peel away the outer bark and let it dry for a year (or two). It doesn't rot in the water due to lack of oxygen.

My suggestion would be steel pole in concrete then build a decorative post around the pole. Whether you bury the concrete or use it above grade is up to you depending on your climate.

My .02

I am a worrywart. My concern with only tamping the posts into the ground is that if you get a good rain (and in Florida that can be a daily occurrence) and then a good wind, a 14 x 40 deck can become a very good wing. Since the ground is wet and slippery, the uplift may pull the posts out. My recommendation would be to put in at the corners and in the center posts of the deck concrete bases designed so that they cannot be easily pulled out and attach the posts to the top of the concrete bases with metal connectors to avoid the rot that others have mentioned.

Yeah, but almost al of our fences are simple tamped posts. I never see a fence set with concrete.

Nevertheless, I would be tempted to make a concrete peer and set the post on that.

AH,

all my fences are tied with Bolts to Concrete Stubs that are dug into the ground along with the concrete, the post and the stub.

I started down this road some 35 years ago on my last house and have never lost a concrete stub yet. Posts yes, as they rot, but you can just cut the post off and fix another to the existing stub.

Wheer I cannot get a post in due to a configuration like a corner, I then use double post or over sized posts.

Works for me.

Soil: River Clay a few hundred/thousand years old.

Enjoy guys

Sleepy

An oldtime contractor I used to know swore by posts tamped in gravel (not crushed stone). Scrape loose dirt out, put in gravel & tamp it good if needed or else set it on undisturbed soil, pack the gravel to 6" from the top of the hole then pour a concrete cap & slope 2" down to grade to seal the hole & keep it dry. It sure worked! Mind you, this is Ontario gravel & clay not Florida swamps (or whatever you have).

When I built a deck, I used Sonotubes set below frost. Or you can try these new fast tubes but I have no knowledge of them. The Sonotubes were installed with hardware to accept 4 x 4 or 6 x 6 wood posts. They will outlive me.

Wow! Fastube looks a nice product. Wish I had thought of that.

Tamp, always, with a large lump of some flat stone set horizontally or so in the bottom of the hole at the base of the post before it is back-filled. Use up the larger material in the hole first, then bash the smaller stuff in on top of it in stages.

Wood set in concrete is just rot waiting to happen.

Meets code, zero ground contact, zero chance of rot:

Exactly!

If you use these ensure that you fasten the beams to the tops with steel joiner plates or use knee bracing or some other adequate means of lateral support- more important the higher the deck is. I learned a few years ago on a simple little job that you have to account for that with these, whereas a set post's bending resistance will usually be enough. Otherwise they're great!

That's the first thing that came to mind.

I concur. Posts set in concrete will rot faster than those tamped in earth.

Never cement in a wood post, the enzymes and bacteria in the concrete will eat into the wood very quickly. Use a post protector of some kind. On the farm we would bush on a very thick creosote then wrap the earth line with tar paper for added protection. 40-50 years later the post had minimum decay at the earth point where as untreated were horizontal in less than 12 years. Tamping with a good heavy tamping bar will set the post for no movement. No utility company in Canada will allow concrete setting of wood posts or poles that I am aware of.

Darn it KRAM, you beat me to the punch yet again! Don't you ever sleep???

I take that this new deck is an elevated wood deck and that the posts at pressure treated ones.

The best approach for a proper foundation is to auger holes large enough in diameter and deep enough to be frost heave resistant. I haven't a clue what the local building codes down in FL state the minimum foundation depths must be and what is the typical frost penetration depth...probably not much.

Inside those auger holes use a SonoTube, usually 8 or 10-inch diameter, that will snuggly fit the hole. You don't want a loose tube for several reasons. First, it makes it difficult to keep the tube plumb during the concrete placement. Second, you need a tight fit of the concrete pier foundation against the surrounding soil mass to resist lateral forces due to wave action (if ever present due to Hurricanes) and Hurricane force winds.

Place a good number of vertical #4 or #5 rebar inside the tube, wrapped with galvanized 3"x3" steel fence. Wrap it a few times to prevent the rebar from moving. Use rebar tying wire to fix the rebar to the wire fence material, making sure you have 2" clearance between the wire fence and the inside face of the SonoTube. This is referred to as bar cover.

Place the concrete gently into the tubes, trying to avoid it dropping more than a few feet, otherwise the aggregate in the concrete will separate from the rest of the concrete mix. If it's a ready mix concrete from a local producer, make sure you get at least 3,000 psi compressive strength concrete, with a Maximum Water-to-Cement (W/C) ratio of 0.42 by weight, no less than 550# of Portland Cement Type II per cubic yard, a maximum concrete slump of 3", well graded fine and large aggregates (w/ a maximum stone size of 1-inch, and 4-6% Air Entrainment. That should be enough info for you to order the ready-mix concrete. DO NOT ADD WATER TO THE DELIVERED CONCRETE, as it will weaken the concrete strength.

As you're placing the concrete into the tubes, either tamp the fresh concrete with rods or a small electric concrete vibrator (you can rent these), but don't over do it to the point where water bleeds to the surface. That's a bad thing to happen.....over vibration will cause segregation of the concrete mix materials, thus weakening the concrete strength.

Once you fill and screed off the top of pier, then it is time to install a galvanized steel post base with it's integral concrete anchor (see post above w/ pic). You must do this before the initial concrete set, otherwise you won't be able to install it.

I highly recommend using a Simpson Strong-Tie "Post Base" of the appropriate size, so that you can secure your wooden deck posts to the top of the pier. You can buy these at almost any lumber yard or big box store. Make sure you buy the type with the "through bolts" and not the ones with the nails (they're El Cheapo). You want to FIX the base of the wood post to the new concrete pier to prevent it from racking and twist. This is essential in a Hurricane zone such as FL.

Don't install the wooden post into the concrete, as they will degrade quickly, even if they are pressure treated or wrapped with building paper. Unless you want to dig up the entire foundation in say less than 10 years or so. With the high humidity, high annual precipitation levels, and high ground water that is found in Florida, you can count on 'wet rot" and mold zapping your PT wood posts fairly quickly. Frankly if it was my deck I'd install TS 3x3x1/4 structural steel tubes instead of PT wood posts because of the rot issues, but that's me.....

=== signed,

CaptMoosie, Ph.D, P.E.

Civil, Structural, & Environmental Engineer

"Over 35 years of Engineering Excellence".

Just got off the phone with my friend. He has done a number of decks in Florida and here is a synopsis of what he said:

1. All perimeter posts are sunk into a concrete hole 36" deep. Posts are coated with Bull Mastic.

2. Interior posts are mounted onto concrete piers with a galvanized pier-to-post bracket.

3. Make sure all wood is installed crown up.

4. Make sure deck has a slight slope to it running away from the building.

5. Important!!! - Use Lifetime Deck Screws. Florida is hell on regular galvanized screws (I know because my fence's screw heads are rotting off).

P.S. If you like these tips and would like to give my buddy some Good Answers, drop them off here and I will give them to him tomorrow morning when he stops by. :)

Here's one! :)

Use a cinder block to increase contact area with soil.Insert post into hole of cinder block, and use concrete to fill voids around post.

If it is ever necessary to replace, simply dig out the block and replace.

You can tamp the block in place below ground, and because of the large surface area provided, it will reduce loading and will be much more secure and effective.

This also prevents post from working loose due to vibration from foot traffic,wind, etc.

I have built hundreds of decks using the method outlined in the Australian Building Standards a precis of which is above. The stumps must be treated to H5 retention level ( if they are C.C.A. treated pine ) and the rest is up to you. The spans given above are from the standard and refer to kiln dried treated pine tested to M.G.P 10 or above ( F5 in the old scale ). You will see that there is no steel in the above system. There have been competitors try to 'rewrite the book' by using patio tube only to come undone when the wood swells and breaks off the fasteners. A Few Tips;once you have dug your hole ( short trench ) throw in a bucket full of water and drag your shovel backwards and forwards to make the bottom smooth and level. If there are rocks throw in a shovel full of clean sand and repeat. Place sole plate in the bottom and tamp down 'till level. The water aids in this. Place posts in the holes and bolt bearers to them at the right height. Skew nail the bottom of the posts to the sole plates. Fill holes with sand/soil and tamp down keeping them plumb.The bearers don't have to be square ( normal to ) or parallel but it helps if they are, specially when it comes to fitting fascias.Cut off the portion of post sticking above the bearer. OR as you can see in my sketch precut the posts with a half lap and cut the posts to the correct length first. I used an auto level but you can use a string line as well.Jim

I'm hearing and seeing a lot of OVER-ENGINEERING going on in this thread, and I'm loving it !

Dig your post holes , dump about 5 shovels full of DRY redi-mix into the bottom of the hole, Prepare the post by putting 2 or 3 , 6" galvanized lag screws into the END of the post ( screw them in about 3" , not a critical length since they are just used to act as both standoffs to prevent the post from pushing too far into the dry-mix, and as anchors to connect the post to the concrete lump that will form at the end ) COAT the parts of the post that will be underground with a coal tar based driveway sealer , then TAMP IT AS USUAL.

The Redi-mix will soak up the natural moisture in the soil , but it will ALSO spread out into the soil a little bit, it will form a big " anchor" at the bottom of the post .

For everything ABOVE GRADE , just follow Building code for Hurricane Tie Downs and the like and I'm sure that it will be your grand-children's kids that will have to post here asking how to replace the damn thing.

:D

It strikes me that there is a key issue here that has not been clearly expressed.

It is about the type of ground connection, for the lack of a better term. The OP talked about planting wood in the ground and making a foundation post that would "break before knocked crooked". The more conventional arrangement is a concrete foundation with a connection to a wood column just above the ground line, the connection of which cannot resist any sideways twisting, (moment loading) and is usually modelled as a pinned connection at the concrete. (unless, of course, the connection is designed to take moment loading, but this is not your normal building supply standard concrete post anchor.)

This may or may not be an issue with the particular deck in question, because we are not made aware of how high it might be off the ground. If it is only a foot or two, then concerns about sway bracing isn't as important as if it were 4 feet off the ground.

Also, the general consensus is that a wood post won't last very long in the Florida environment and since the OP wants his deck to last "a long time" maybe a tamped wood post isn't the answer.

However, if he wants a post that will resist sideways motion without angle bracing then he does not have an anwer except for Moosie's suggestion of a steel box tube cast into the concrete base. Although I would suggest a wide flange or angle section to avoid trapped water and hidden corrosion.

Another suggestion would be to extend the concrete pour up to the underside of the horizontal supports of the deck and essentially use a "concrete post". (suitably reinforced with rebar to resist side loading.) The OP might precast the post and tamp it into place. Alternatively, he could simply pour an augered hole full of concrete (and rebar), and form any type of fancy shaped post on top of that for the appearance portion of the concrete. Pouring directly into the augered hole would be as good or better than the best tamping job.

Hope this helps,

Jon.

Sawmill, I'm with you on this one, where you suggest that the concrete piers be cast to a height far above the groundline in order to directly support the deck beams.

Exactly 20 years ago I spent an entire summer constructing a multi-level PT wood deck in the same manner, w/o any posts to support the deck. This was a fairly large deck (about 1,500 SF) that I added to the rear on my 1896 Victorian home which my X now owns. The highest portion of the deck surface it sits about 8.5 Feet off the ground.

I cast the dozen plus piers in 12-inch SonoTubes that were reinforced with #6 (3/4" dia.) Grade 60 bars, all wrapped with 2 x 2 galvanized welded wire fence material at least 4 times, all to provide proper reinforcement. I provided Simpson Strong-Tie galvanized beam-to-pier connectors where the main 3-2x10 beams rested on a concrete pier.

The last time that I saw it, it was doing great and not rotting out. My 3 grown kids reported the same, even if my X has not taken good care of it by staining and applying water repellent to the PT lumber. This deck is located in the wet & cold climate of upstate NY and receives a considerable amount of snow each winter (over 66-inches per annum).

I only wish that I had some pics of it to post here......