Decking Footers

Teetorbilt

I'm preparing for a new deck and am looking at lifetime footers.

What I'm considering is Bigfoot bases, 6" PVC pipe to underdeck level, 4 shots of #5 rebar (coming up about 2" short) and then poured concrete. Bolting positions would be pre-determined and drilled into the PVC with greased knock out rods placed prior to the pour.

We live on sand but deal with a lot of water, salt and termites (with the Formosa's on the way). My thought is that this will outlive me even if I have to replace the deck a few times.

Any thoughts?

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rino1494

What size posts are you going to be using ?? I suggest maybe using a larger diameter pipe for the concrete. Maybe upgrade to a 8".

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Greg Di

A 6" footing seems small to me for anything. I usually use 12" with bigfoots to make things bombproof, but it all depends on the overall job.

Teetor, why PVC instead of a sonotube?

mdshunk

I was sorta wondering the same thing. My guess was to prevent soil minerals (salts?) from working on the concrete. We'll see what he says.

6" doesn't seem so small if you've ever looked at how small in diameter the piles look when driven for a tall building when compared with the footing size. That's sorta what the idea is here with these proposed deck "poured piles".

This is interesting stuff...

PipeGuy

Teets,
How tall (above grade) will the concrete columns be?

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Teetorbilt

Standard design/build around here are 4 X 4 PT set in concrete just like fence posts. They last about 10 yrs, unacceptable to me.

A number of smaller posts as opposed a few larger ones serve a few functions, the main one being uplift during one of our little wind storms. The second being reducing flex, I can't stand a bouncy deck and we still party like rock stars a few times a year.

md hit it about the PVC. Salt is everywhere here, I'm just minutes from the ocean, eventually it gets to the rebar which expands and causes failure. Another factor is that I have a large stack of 6" behind the shop that's been there for years waiting for a project.

Rich, I'm going 3' below and 12" above grade. Got to stay below the frost line. Most guys just go down 2' but I don't want this thing to fly into a neighbor's house. I also plan on having temp. wind skirts that will go to the ground when the shutters go up.

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PipeGuy

I built my 16x10 wood frame shed on (6) unreinforced, 8" diameter, concrete columns. The tallest columns extend to about 24" above grade. I used PVC sewer pipe (SDR-35) as form material and left it in place. I used the same principle as the big foot at the base of the exacavation but simply overdug the footing width at the bottom. There's been no discernable movement of the columns since the shed went up 5 years ago.
I suspect the physical properties of the pipe itself approach those required to support the compressive loads of the shed. If one was to use SCH-40 PVC I think the pipe would in fact meet the load requirements. I don't think rebar in the column provides much benefit if the PVC pipe is otherwise left in place.

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Teetorbilt

This will be approx. 30 X 20.

First change order: It will now be 18" high to allow for seating alongside the pool. Angled seatbacks will assist in supporting the railing which was originally freestanding.

This is sewer pipe left over from a ah-hem project. It was given to me in exchange for getting rid of it.

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You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

AtlanticWBConst

Teeter,

FWIW: Around our parts, it is code and standard practice to go 4' below grade because of the frost line. We do 12" Dia. footings... most towns have now adopted that from the 9" before. We like to use 6'x6' for our large decks. We use these to support the deck beam and for the main deck support posts. Also: we use strips of water and ice shield over all doubled joists (doubled- rim joists too) so water can't get in between and freeze and expand them causing slight separations. When we install the ledger boards to the sides of the house (the Ledger is installed over a water and ice shield layer) we cut and install 3/8" - 1/2" PT 'spacer strips' to allow for additional moisture drainage and ventilation. (Alot of poorly installed decks 'sandwich' moisture in that space between the house and ledger and cause rot in the sheathing) Lastly, we put blockers between the centers of the joists that span the deck - to lock them together and reduce flex and bounce. These especially make a BIG difference.

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Teetorbilt

Atlantic, the frost line was a I live just north of Palm Beach, FL.

Some good info though. How well do you think that it would stand up to 40 fat old folks getting down to 'Strokin'?

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ricpacer69

Hey, I resemble that remark Stroke it to the North and Stroke it to the South... You know the rest.

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