Timber for water feature

[Stephen Blair]

I am needing to find out what timber is best for being 90% submerged in water to retain a soil bank, there will be fish in the pond, so I can't have any proservatives leaching into the pond.

it will also be held in place with concrete, so do I need to consider swelling etc, as I do not want it to move, break the concrete and create a leak.

Cheers:)

[niftysteve]

how about untreated oak sleepers give them a good soak before they are fitted

[twmarriott]

use green or purple heart, often used for dock and pier pillings, doesn't rot and is indestructable,

[sloth]

Elm? Used by Romans for water pipes, so good when submerged...

[Pedroski]

We always use untreated oak. Works perfectly and lasts foralmostever. In clay it darkens quickly. Looks fantastic as it changes over time. We very rarely put it into concrete, prefering instead to just dig it and ram it in a good way, and then tie it all together using Timberlock type screws.

[Stereo]

Alder is also good for this. Doesn't rot under water.

[treequip]

They make canal lock gates out of oak and they are wet pretty much all the time

[jrose]

I'd second the vote for Elm if you can get it, if my memory serves me correctly it's what was used for canal lock gates etc

[agg221]

I'd avoid the concrete if possible. Oak is durable because of its tannin content, as I believe are purpleheart and greenheart. Tannin is tannic acid, concrete is alkaline, where they are in contact the tannins are rapidly neutralised and you get surface rotting, so they no longer bond properly (as many owners of wooden boats have found to their cost). These three have the advantage that the waterline and unsubmerged areas will also be durable.

 

Elm is good, as are pitch pine and alder. All of these need to be wholly submerged - the area around the waterline will be attacked rapidly.

 

Whichever you use, only the heartwood is durable - sapwood will disappear pretty fast.

 

Alec

[littlerob]

alder and submerge in water and never rots but mite no get massive sized bits