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I am looking at building a swimming pond and the deep end would have a wooden wall. The company I am buying the design specs from typically uses cedar for the wall. (Just so you can envision - the first three feet down are gradually sloped from all edges, and then the deep end is an octagon with a 3 foot wall at the edges.)

I have quite a few white oaks I am cutting down this winter and thought that wood from them might make a longer lasting wall (or at least as long lasting wall). This wood will be fully submerged under water 100% of the time. Likely to be cut into 5 X 5 or 6 X 6 beams and then stacked about 3-4 feet tall.

My question is if I use the white oak that I cut down whether I need to still wait any time for it to dry (or get it kiln dried) or if because it will be permanently submerged under water if drying it is not necessary at all and I can just use it as is.

I also will be cutting some black oak and black walnut - but guessing white oak is the best for this underwater application given the closed cell structure and it being known for making boats, barrels, etc. Am I correct in this assumption?

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  • Oh this is a good one! Unfortunately I don't know of any data about whether fully wet applications are better with the wood green or previously dried. I believe dock pilings were green when used, but that may not have been universal and those species chosen could have played a part (as e.g. elm does in underground applications). If you were to air-dry it, you'd be waiting quite a while to complete the project — the rough rule of thumb for drying wood applies quite well to oak, and it's a year per inch of thickness. Not sure if kiln drying would be feasible, it's certainly a possibility though.
    – Graphus
    Nov 13, 2023 at 7:53
  • "I also will be cutting some black oak and black walnut - but guessing white oak is the best for this underwater application" This is a separate query and should have its own Q. Good news on the ABW front, that's classed as very durable in terms of decay resistance (don't know how that translates to constantly wet applications, but indications are good). Re. the black oak, the thing that matters is whether it's in the white oak or red oak families. Using modern naming convention "white oak" and "red oak" aren't species but classification by type based on physical structure.
    – Graphus
    Nov 13, 2023 at 8:06
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    I would think there is no reason to dry it out. The Drying process is meant to stabilize the wood (as much as possible) before using because as it dries it has lots possible movement, especially if you are doing any kind of quality woodworking. Submerging the logs will just absorb that moisture right back.
    – bowlturner
    Nov 13, 2023 at 14:40
  • No experience with black oak, but you can easily see if it’s a closed tube (like white oak) or an open tube (red oak) structure by sucking on end grain. Nov 15, 2023 at 21:28
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    @AloysiusDefenestrate, indeed! Visually though, one family can be distinguished fairly reliably from the other if the end grain can be prepped well, either sanded very finely or pared/planed smooth. If the tree is the known black oak varietal from NA the Wood Database will of course list which group it's in; the hard part with this method however is actually in definitively IDing the tree.
    – Graphus
    Nov 17, 2023 at 10:02

1 Answer 1

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I don't know of any data about whether fully wet applications are better using the wood green or previously dried. Some applications requiring the wood to be constantly wet in service did start with green wood. This includes some or most dock pilings, as well as the elm used to make some piping historically.

However, there is a possibility that this was merely due to one or more practical considerations and had nothing to do with a known, or supposed, superiority of the wood for this application!1

Regardless of any significant difference in decay resistance for white oak in this application, do bear in mind if you wanted to air-dry the wood you'd be waiting quite a while before you could proceed. Properly stickered and stacked, the rule of thumb for drying of "a year per inch of thickness" holds reasonably well for white oak....

Kiln-drying is obviously way faster, but may not be feasible for a number of reasons2.

or at least as long lasting

Just as a general point, while white oak is definitely durable, it is still classed somewhat below American cedars in standard classifications comparing kiln-dried wood. See here for example.

Important note: the various tables and data sets you might find online relating to decay resistance or exterior durability are mostly or exclusively based on the heartwood. So it's important to go into this knowing that the yield of suitable wood (suitable for this project) from any of these trees could be substantially lower than expected; although this likely applies most to the black walnut which you may not want to or need to make use of for this.


1 The difficulty, expense or time-cost of drying the wood in these dimensions.

2 Including being able to find a suitable service within a reasonable distance, and the added cost.

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