Pond Boss Forums POND CONSTRUCTION Creating habitat PVC Piers for Dock Question

Jeff, when you guys poured concrete in your pipes, did you pump the water out first? Or did you just dump the dry sack-crete in? A buddy said I should mix in fiberglass to make it stronger with some portland cement. Any thoughts there?

I don't think it will matter either way if you use the concrete. The pipe will be strong enough without it to support the load if you put enough of them in. What I'd be more concerned about is the racking of the piers. Even wood, which is ideal for this, needs diagonal bracing to lock the posts into an upright position.

What was the reason for not using wood?

Eddie

I agree the racking was a concern with me, but I was hoping that if I got the pipes in deep enough and filled with concrete, It would be heavy enough that I wouldn't have to worry about cross bracing. Also, I am not sure how I would cross-brace the pipes.

I did cross brace the wood posts on my original dock. And, the dock would of been fine, if I would of set it up high enough out of the water. That was my goof.

I am just not sure how I could use a wood post now? The ones on the dock now are too short and the ones in the front are lose in the ground.

I have nothing against the wood posts. I just thought the concrete ones would last longer and would not be able to heave or shift as easy.

Is there away to cross brace the pipes? Should I be concerned about it?

If you do not brace your posts with diagonal cross bracing, the deck with wobble on you. You will need to make an X from post to post at the end and on both sides at the very least. Maybe more depending on what you use for posts and the size of the deck.

Concrete isn't going to remain solid inside a pipe if it's moving around. My guess is that it will crack inside the pipe almost immediately and just become filler without any structural significance.

If you were dead set on using pipe, you might consider adding T's to the posts. I don't know if this will work, but think it might if you connect all the posts together about mid height.

With good bracing, it really doesn't matter how deep into the ground your posts are. Depth for posts is dependent on what you are building. For fences, the concern is with heave and wind load. Usually 2 1/2 feet is plenty for a 6 foot fence, but in some soils, you need 3 to 4 feet. For a pole building around here, 3 feet is good, but 4 feet is even better. For a deck with good bracing, I go down two feet, or until I hit rock. In soft sand, I add concrete to my posts, but in clay, I use the clay to back fill.

For the pond, all you need to do is get down to a solid base. A concrete cookie at the bottom of the hole would be a nice bonus, but you're goal isn't wind load or heave resistance. It's to create a solid base to support the load of the deck.

Or you could just go up in size until you get to a post thats thick enough to withstand any lateral movement. What that is in PVC, I have no idea? LOL

If you go with wood, be sure it's rated for water contact. Most pressure treated wood that you buy at the stores will be rated for contact with the ground. Post for piers have a higher level on chemicals in them for constant water contact. I know allot of guys use the posts they buy from Home Depot or Lowes without any problems, so it might just be one of those things that you have to make the call on.

Good luck,
Eddie

At my parents house that's on a public lake (that doesn't need the piers removed due to the ice) we used 2" galvanized pipe w/out cross braces. 8' pieces of pipe sunk between 4 and 5 feet into the bottom of the lake. We did use clamp on twisted figure 8's to connect the two pieces of pipe together, then set the 2x8 runners on them. The pier is 60' long and 4' wide "L" shaped. Hardly any wobble.

Sean, we did not pump the water out, but we did make sure it was a slightly dry mix in one and used the water and a piece of rebar to mix it in the pipe in another. Using the mix was easier and it pushes the excess water out itself. We used a big cheap plastic funnel to route the cement into the places we wanted it. The 4x4's allowed us to put cross bracing in easily by just nailing and bolting, not sure how you would do that on a piece of pvc

Jeff,

Did you cross brace after the wood post were in the water? Did you pre-drill holes for bolts?

I could pre-drill a couple of 1/2inch holes in the 8" pvc pipe, then slide through a long galvanized bolt before I fill the pipe with concrete. Then I could later attach a treated 2x4 to for cross bracing.

I am not to concerned with cross bracing perpendicular to the bank. I think since my docks ramp will be tied to a concrete slab on the bank, I don't think that I will get much movement that way. But, I think eddie is right, it wouldn't hurt to have some cross bracing, especially parallel to the bank (between the front and back two piers).

I was also thinking that I could also drop a T post in the center of the pipe (along with some rebar) for added strength.

Have built several docks using PVC filled with concrete. Using 4" pvc schd 40 pipe, we drive the pipe until we hit hard pan (here in FL it is usually 4'. We wash the pipe in using 3/4" pvc attached to a hose washing on the outside or we use a 1 man post hole auger to dig in 3' or so. We then seat the pipe in the hard pan using a drive mechanism (the steel weight used for table umbrellas works great. Turn it upside down with the pole holder fed into the pipe)

We then cut the pipe to height and set the beams(or ledgers) that the joists will set on with galvy carriage bolts. We slide in one 5/8 rebar and pour in concrete. We install post every 8'.

My 1st dock done this way was installed 9 years ago in a tidal area. 5' x 50' with a 16x20 end. Is still standing with no deterioration on the sub structure. Has been extremely stable with no cross bracing. No settling, sagging, swaying...still.

The question of pvc vs wood post is all about durability...and pvc wins hands down.

Okay boys, I finished installing the first pipe for the new dock. I went ahead and used the 8" pipe...That may have been a little over kill. It was fun driving that in to the ground! I end up only getting it in about 2 foot. The whole floor of my pond is solid clay, so I think I am good. I took my ice auger with the extension and went in a little deeper.

I put one 1/2" piece of rebar in the middle and took some woven (American) wire, made a circle and placed it in the tube before I poured the concrete.

I also placed a couple galvanized bolts in the side, close to the top of the pipe so I can bolt my ledger board to.

I am thinking that 4" pipe would probably have worked just fine. 8" is way over kill. It took 5-80lbs of concrete.

I am hoping that with the pipe only 2' in the ground, that it will still work. I am not worried about it lifting up, I am starting to wonder if it will start pushing in to the ground further over time.

I made sure that I am plenty high out of the waters reach this time. This may also save me if it starts to settle.

I will get some pictures for you guys later. I plan on getting more pipe and concrete tomorrow.

Any advise on how to get the wife to stop asking questions?

Legal or illegal?

I've found that they really don't want to hear the answer, so I like to stop what I'm doing and engage them in a long, drawn out explination of what I'm doing, why I'm doing it and what I hope to achieve. It doesn't take very long for those that are annoying me to lose interest and find a way to escape my answer, but to drive the point home, I then like to push it and bring it up later with further explination of what I'm doing and why I'm doing it. Then when I run out of things to say, and have said it all at least three times, I thank them for their interest.

My ex wife is who I'm thinking of for this reply, but my parents are also victems of my replies from time to time, as is my brother and a few current inlaws. My wife, Steph, is actualy able to comprehend what I'm doing by just watching me and helping out. But then again, she's smarter then I am, so she picks up on things faster the I do.

She came up with a name for what I do. She calls it "Hookey" Like in playing hookey from school. I had a friend of hers tell me that she was playing hookey from work one day and that we needed to do the same thing. She sort of annoyed me, so I went on and on about not knowing what hookey was and that I had never heard of it before. Now when I go on and on in one of my replies to somebody who is annoying me, she calls it "Hookey."

Eddie

My Wife doesn't ask a lot of questions unless I reach for the checkbook. However, I have started heading to the country during the week when she isn't there. That way I can get a lot more of the important things done without the HoneyDo's.

Like a good nap I hope!!

Naps are almost necessary when the temp hits 100+.

I have just enough stuff going to keep me in the metromess this week.

My wife has learned she doesnt want to know,so she doesnt bother asking too many questions.When she does ask,I usually get one of those "your nuts"looks from the answer.And yes,she's probably right most of the time.

haha! You guys sound like me in so many ways. The one thing that is driving me nuts is that she asks the same questions that I am thinking in my head! That I do not have the answer for.

She suggested that I drain the pond 5 feet and do it right. Then Pour a footer and a concrete column on top. pfffff. What does she know!

Ohh well, what do you do?

Back to my project...I have drove the 8" pipes in. I filled one with concrete and rebar. The thing that was concerning me is the racking. Only being in two foot in the ground is concerning me. So, I found a great way to brace it. I took a piece of 10' long galvanized pipe, smashed one end flat and drilled a hole in it. I then drove it into the ground at an angle and slid it over one of my bolts at the top of the pipe. This worked great! It will be like the X bracing that was suggested.

I am thinking if I would of used the 4" pipe idea, this may have worked better. I bet I could have got them in the ground deeper. I may not have needed any bracing.

Can you get a picture of the bracing?

Okay, I got the second pier in. This one went in much better. And, I learned a few things on the second one. First of all, I was able to hammer the second pipe in about 2 and ½ feet this time. I made the handle a little longer on the auger so I was able to get down a lot deeper. By augers the inside deeper, I was able to drive the pipe deeper. I even augured down about a foot deep then the pipe. I then put the rebar, wire mesh, and bolts in. Filled it with concrete and let it set for 3 days. When I came back, it was very stout! There was hardly any movement in it at all. I think this will work like a champ.

Otto, will get some pictures of the brace I put in on the first one. Although, if I can get the remaining 2 pipes in as deep as I did the last one, I may not need the brace. Although, I may leave it there for good measure.

I will get pictures on here soon.

Here is the Auger that I am using to get the mud/clay out of the inside of the pipe.

Here are a couple pictures of the pipes I have drove in. The ones sticking further out have not been drove in yet.

And here is a picture of the brace I put on one of the piers. I really don't think I need it now. But, I may leave it there for good measure. After I get the dock complete and if it feels wobbly, I could add others. But, I really don't think I need it.

Here is the dock completed. I don't think I need any more bracing. I put one brace on one of the piers...and I don't know that I need it. For now, it is very stable. I will post some better pictures soon. Thanks for everyones help! I will let you know how it withstands the winter.

Looks darn good to me!

There is no picture that does not look better with kids in it.

Emma loved your dock and wants one for our lake