Suggestions for 2 foot high wall on pond?

[shanezam203]

I am building an L shaped pond and digging 4 feet down but do not want it to be ground level. I was thinking of building the frame of the Pond with 4x4's and staining it & putting on a nice 2x8 Cap.

What other options do I have? I looked into a vinear stone, I could side the front 64 square foot with stone & mortar which would look nice. Or landscaping blocks but that would take some time to get them level because the ground has a bit of a slope to it.

Any thoughts, how long will Cedar 4x4 posts last in Chicago winters and how nice will it look stained?

Shane

 

[JCschild]

retaining wall blocks, easiest aside from the leveling.
stone and mortar nice look to it but lots of work, plus your ground will probably move a bit after getting completed
if you go up 2 ft high then you dont need to dig 4' deep.. unless you are making a swimming pool rather than pond

wood is the last thing i would use, even PT will check, warp, discolor, require re-staining i used to make a lot of my flower beds with PT, now i do only retaining wall blocks or use landscape edging for low level.

https://www.gardenpondforum.com/topic/8774-another-leaking-waterfall-thread/page__fromsearch__1

pics of how i used retaining wall block

 

[shanezam203]

Nice pond and waterfalls, real nice. I'd like to go 4-6 feet deep to ensure it doesn't freeze in our cold winters. I like your retaining wall blocks a lot, that is originally what I wanted, but I am afraid it will be difficult to level on my lot because the yard is sloping a bit. 4x4 posts will be easier to level and work with but I understand they will require maintenance and will not look brand new forever.

Can I dig 4 feet and then about a foot back (so I have a ledge) build the base of the pond out of the 4x4's pressure treated & stain it but then in time add the stone finishing to the front facing sides?

 

[Waterbug]

Here's 2 ponds I built in order to learn about different materials.

The wooden pond was 700 gal, 5' x 8', 2' deep. 4x4 pressure treated beams, lapped corners, 1/2 plywood inside on a concrete slab, 3/8" threaded rod through beam and into slab at corners and mid wall. Notice I didn't fill in with 4x4 to make a solid wall. Almost all the stress is in the corners and filling it with 4x4s wouldn't help strength, but I did have to put plywood on the inside.

There was another wooden pond upstream of this one. It was 1,700 gal, 11' x 7', 34" deep, 4x6 pressure treated beams, lapped corners, 1/2 plywood inside sitting on a concrete slab that was part of the driveway. Threaded 3/8" rod anchored into the slab and screwed tight at the corners and mid point in each wall. This pond bowed out along the 11' sides when filled and I had to add a 4x6 laid so the 6" was horizontal, bolted to the 4x6 below to order to straighten the bow. But I'm pretty sure it was at it was close to it's limit, which isn't good.

The stone pond in the foreground of the picture is a 300 gal, 6.5' x 3.5', 2' deep. Mostly raised, 6" wide concrete block dry stacked and filled with concrete. Sonoma Pink limestone veneer, sculptured rock cap using mortar.

What I learned...
I grew up working with wood and had little experience with concrete so my assumption was the wooden ponds would go up fast and easy. But in the end, after also building ponds with concrete block, I would never build with wood again unless the look of wood was a requirement. And even then I would build with concrete block and then face with wood just as decoration.

Concrete block is easier, faster and cheaper (but not a lot cheaper 10-15 years ago).

I took something I learned from log home building, that you have to put threaded rod thru the beams vertically so as the beams shrink in height you can tighten the nuts to pull the beams together. I think that's needed. I've seen people just spike the beams together which does seem to work, but I've never seen anyone post a year or two afterward to show how they held up. Spiking is no day at the beach either.

The scariest part is really the corners. There just isn't that much wood there and because it's the end it would be prone to splitting. Very weak. If I did it again I'd put 45 degree braces in the corners using metal and wood so the inside corners were kind of rounded.

Overall I think the smaller pond was OK strength wise, So to me an 8' length would be about the max I'd go with wood.

I torn the wooden ponds down after 3 or 4 years to see how they held up. These ponds were in San Jose CA, so not much rain and they were on a concrete slab. The plywood had rotted thru at the bottom in a couple of places. That could have been a real problem because of the way I lapped the beams.

There is absolutely no way I would put pressure treated wood in contact with soil. It does rot. In most applications a little rotting is no big deal. Not the case when holding water. We used Redwood for fences in CA and that started rotting in the ground pretty fast, and a 4x4 would normally be rotted thru in the 10-15 year range. But I'd expect with water pressure to fail before that.

Concrete
Turned out concrete wasn't so difficult. You know how masons run strings and mortar each joint to keep each course level...you don't have to do that. You do want the first course to be fairly level, but even that isn't super necessary. After that you just stack the blocks, no mortar. Called dry stacked. Then fill the blocks with concrete so the result is basically a solid concrete wall. The block you use is kind of important, you want bond beam type block so the poured concrete will form a continuous structure. It also allows adding rebar which is very important.

To face the block I used small rock normally used as ground cover. I liked the look of the small rocks and very inexpensive to buy, not inexpensive in time. I enjoy the work but it was tedious. Many more options for veneer. Just stucco, slate is a modern look and inexpensive, flag stone and fake rock that you buy or make yourself.

Imo wood has to be on a concrete foundation to keep it off soil. That's most of the work for a concrete wall. Easier to lay block on that foundation than it is to attach wood.

 

[shanezam203]

great information over your years of work, thanks for sharing. Now I am torn between wood & stone. I should do Stone or Landscaping blocks, I'm just afraid my ground is not level, so my 1st row will take me a long time to get straight.

I think regardless, my 1st priority after I dig is to level the area around where I'd like to sit my pond. Then I may have an easier time with Landscaping blocks or concrete blocks & fill it in with some glue or concrete.

Anyone else 1st start with Wood and then tear down & put up a brick above ground pond?

See attaached, how long would the below wood 4x4 post pond last (not on concrete)?

 

[JCschild]

did you look at the slope my pond is on? talk about levling nighmare.. just start at the high end and work your way in.. really not that hard.

you really need to get off the wood thing. besides it has to leveled as well or it will look like crap.. no matter how you slice it you have diging and leveling to do..

wood you will be replacing eventually and complaining about quickly
stone... call er done..

 

[Waterbug]

There's no way to tell how long the structure pictured would last. Could fail as soon as it's filled with water, could last 50 years. Not really enough info to make a good bet.

There's a fair amount of data on different woods in contact with soil vs concrete. But all I've seen have to do with things like sill plates and such where the wood can rot a lot before causing a problem. You're talking about a single bolt in the corner of a 4x4, 2" from the end, holding back tons of water. I know of no charts for that.

With concrete block slope isn't much of a problem. Build up the low spots with block. Make sure you have a reasonable footer.

There was a thread here I think of pond made from rail road ties I think. They didn't have a foundation if I remember and had to keep trying to add a temp foundation to prop it up as one end sank. Might be one to search for.

 

[HARO]

Waterbug; (and anyone else who's interested)
Regarding your thoughts on placing wood on a concrete slab; here in Ontario the building code forbids ANY wood to touch concrete without some kind of barrier between them. Apparently the chance of rotting is too great. :twocents:
John

 

[sissy]

Thats because of your snow and how long it will come in contact with moisture .I know here you need to put sill sealer between concrete and wood no matter what you build and metal termite flashing .Termites are bad here because of the trees left on the ground after they cut a forest down .But even back in NJ we had bad termites and need a termite test when you sell a house or buy one .

 

[shanezam203]

Thanks for the suggestions, now I am leaning towards a split faced 16" concrete block base, what are your thoughts on that? Tamper the area, lay some sand if possible.

Then starting on my LOW side, and once I am level, with a string work around the base?

 

[Waterbug]

Regarding your thoughts on placing wood on a concrete slab; here in Ontario the building code forbids ANY wood to touch concrete without some kind of barrier between them. Apparently the chance of rotting is too great. :twocents:

I think that's great code. Unfortunately most places in the US allow pressure treated wood in contact with concrete. It even allows untreated wood to be in contact with concrete in some cases, like distance to soil. I would always place a gasket between the concrete and sill plate. It's very cheap and also acts as an air flow barrier. While pressure treated wood may not rot it certainly will absorb moisture from the concrete. Moisture in an enclosed space isn't good imo. There was a time when the US lead the world in improving building practices and many, many other areas. Now days we're too busy telling everyone about American exceptionalism.

Thanks for the suggestions, now I am leaning towards a split faced 16" concrete block base, what are your thoughts on that?

I assume these are hollow core? I don't think you can get those in bond beam. You could of course cut out some of the webbing to make them bond beam, lot of work, but not impossible.

Here's a picture of a pond built without using bond beam. Notice a problem?

Building with concrete block is super easy...but you do have to follow about 3 rules that take about 15 minutes to learn. DIYers love to invent new ways, which is fine, as long as you're willing to accept results like above and chalk it up to a learning experience. But in this case not using bond beam block has been tried many times.

Tamper the area, lay some sand if possible.

Only 2 issues.

Never lay a foundation on tamped ground. Professionals are allowed to do this with extra permits, soil engineers, etc. Code requires foundation on undisturbed soil. It's one of the main things an inspector looks for. You don't have to follow code for this project I assume...but why not use the best building practices especially when basically free.

Never lay a foundation on sand...or crushed rock, gravel, etc. The only exception is when the ground IS sand and then other building methods are used. Sand has no problem moving out from under a wall over time.

Then starting on my LOW side, and once I am level, with a string work around the base?

OK, here's kind of the rub...Earlier I said block was easy and you didn't have to worry about straight lines. But that was for block that was going to be veneered over. With split face you need to mortar each course because the joint line is a big part of the final look imo. Lines have to be straight or it would look bad imo. I've done a fair amount of masonry work but I would not do such a project. I could do a pretty good job, but not good enough. I would see my wavy lines every time I looked at the pond. I'd hire it out if I wanted split face. The trick to good DIY imo is picking a look you can pull off.

My suggestions for dry stacking bond beam block...
Dig the footer. Lay a bed of wet concrete, stiff as mashed potatoes, in the footer, just enough for a couple of blocks. Then you can wiggle the block down to the right height. Let that set for 24 hours before laying the next course.

Or...there is a DIYer trick that's pretty good. Instead of sand use dry concrete mix, no water. That gives you a long working time and if half way thru you spot a problem you can just redo it all. This method does require some care later as the block is not locked into set concrete and over all it is slower. You're trading time for experience and that's a good trade for a first timer imo.

Try for at least 1-2" thick of the dry mix. It will set up over time just from the moisture in the ground which holds it together unlike sand.

After the first course is done you can back fill with more dry concrete mix, maybe 1-2" up from the bottom of the block and also inside the block. This is insurance to keep the blocks from moving out of place. Now you can lightly spray water on to the whole thing. This isn't to set the entire 4" of concrete, just get it started.

You should wear a mask when working with dry concrete mix. You're going to breath in a lot more than when just mixing a few bags.

Lay additional courses and fill with concrete pretty much as you go. Not a good idea for a first timer to try and fill too many courses. Each course gets one strand of rebar. This PDF explains how to overlap rebar. Corners are most important, solid strand there. Vertical pieces of rebar are wired tied to the horizontal pieces so they don't sink thru the dry concrete mix and into the soil which is bad.

 

[Waterbug]

At the top the vertical rebar must stop 2-3" short of the the poured concrete. Rebar has to be completely enclosed on concrete as rust protection. Rust expands and busts concrete.

 

[SE18]

At the top the vertical rebar must stop 2-3" short of the the poured concrete. Rebar has to be completely enclosed on concrete as rust protection. Rust expands and busts concrete.

correct; I've seen first hand how rebar cracks concrete, as I believe rust expansion is around 33%; perhaps most common mistake.

Thru trial and error I've used nearly 100% concrete, cement, mortar, rebar for construction. Your replies, btw, are very detailed, accurate and understandable. I've noticed you've helped scores of people (if they heed your advice, that is). I'm sort of a trial and error guy; with many trials and errors.

btw, I've inhaled a lot of concrete dust and other toxic chemicals so I should likely be dead soon. Hopefully not.

cheers

DaveV

 

[sissy]

I like retaining wall block it is made for dummies and as long as you are level and have a good tamped base it is easy and takes less time and if in the future you decide to go bigger it is easy to take apart and expand it .I did one and have also added to it and changed one side and went bigger .I may be a dummy but find this is the easiest way to go .If in the future I do decide to sell this house it will be easy to take the pond down and move the fish to there new home .Most ponds are not an asset to a home on the market for sale .

 

[Mucky_Waters]

Although I believe Waterbugs suggestion to use bondbeam blocks and rebar is stronger, most block retaining walls use this sort of reinforcement. It can be used with split faced blocks with a mortar seam, and would be more than adequate reinforcement for a short wall,,, providing you established a solid footing.