Timber for water feature

[tommer9]

Elm superb when always wet, as is alder. Not good if drying and then re-wetting. Oak is VERY durable, as is chestnut, but I have a feeling the tannins will affect the fish negatively.

As agg says- try and avoid concrete atr all costs if you can, it will drastically reduce the life of whatever timber you use.

In fact whatever agg said was bang on TBH.

[Stephen Blair]

The ground is sandstone, and has been pecked out with machines, the timber will be trenches in and the pond is going to be lined with concrete, we are not using rubber liner for numerous reasons so isn't an option. So that's why, the timber will be concreted in vertically, oh and the post need to be round , once again for numerous reasons .

[Pedroski]

Elm superb when always wet, as is alder. Not good if drying and then re-wetting. Oak is VERY durable, as is chestnut, but I have a feeling the tannins will affect the fish negatively.

 

We've never had a problem with the tannins. From research I have done, they are generally harmless to fish, but may slightly alter the pH of water which could possibly affect very sensitive species. That said, with an outside pond the biggest outside input that will alter pH is run off from the surrounding land and rain water. Tannins from oak in the water will be insignificant.

[antipesto]

Oak would be my first choice but as already said the tannins may contaminate the water on a sealed small pond, probably ok on canals and lakes where there is a vast volume of water to dilute it if it does have any effect. We once made a small pier out of Iroko. It's used a lot for hardwood decking boards. Very expensive wood but good stuff - apparantly they used to make boats out of it

[agg221]

The ground is sandstone, and has been pecked out with machines, the timber will be trenches in and the pond is going to be lined with concrete, we are not using rubber liner for numerous reasons so isn't an option. So that's why, the timber will be concreted in vertically, oh and the post need to be round , once again for numerous reasons .

 

This is going to be really hard to make work.

 

I presume you're looking to fill the space behind the posts to create the waterproof seal?

 

Whilst you've rejected butyl liners, have you rejected puddled clay? This will work much better with timber posts. If they have to be round I'd use sweet chestnut as it has minimal sapwood. I would strip the bark and possibly even shave off the sapwood if I wanted to get a good tight fit.

 

If clay can't be used, the only other thing I can suggest is that rather than concreting the posts in, make the pond a complete concrete structure with shuttering, to form a vertical wall. Then wire the posts together with stainless steel wire and staples, tied to the edge to stop them floating. This will make them much easier to remove when they need replacing. I would then use something like larch, still strip the bark as it would be annoying if it fell in the water, and reckon on replacing every 5yrs or so.

 

If they must be concreted in then I'd probably go back to chestnut but just reckon on ripping out the whole pond in about 10yrs and re-doing it. You might just be able to make it work if you stripped back the SC posts to heartwood, then painted the parts which will be in contact with the concrete with liquid DPM.

 

Alec

[tommer9]

We've never had a problem with the tannins. From research I have done, they are generally harmless to fish, but may slightly alter the pH of water which could possibly affect very sensitive species. That said, with an outside pond the biggest outside input that will alter pH is run off from the surrounding land and rain water. Tannins from oak in the water will be insignificant.

 

Cool . You learn something new every day. Esp on this forum:thumbup:

[skyhuck]

Elm would be my choice.

[skyhuck]

 

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.

 

 

 

 

Alec

 

What tree does Pitch pine come from??

 

Me and my dad (he's a joiner) have discussed this many times and have failed to come to a definitive conclusion.

[Tom D]

Alder is extremely rot resistant when permanently submerged, but not good out of the water. Basically use what you can get..

[Nellybelly]

I'd go for alder, oak and sweet chest nut tannin is really acidic and if they'r going to put koi , orf or ornamental trout in there they wont tolerate a low p,h level