Timber in Water

[SteveW1000]

Hi as a mainly lurker I'm seeking your advice. A friend is working with a school to build a wildlife garden and they want to build a jetty at the edge of their pond. The current plans are to have some posts going down in the water to support the end, apart from elm what other wood would be suitable? As money's tight we'll probably be tapping up the borough tree surgeons for some green timber.

Steve

 

[TheTiddles]

Scaffolding poles can be hidden and are tough enough to bang into the mud very deep to make a robust base

Aidan

 

[CHJ]

Elm is OK if permanently below water but will not do well at water air interface where it will be regularly changing between wet and dry. (Elm is used for Lock sills for instance where they are permanently immersed.)
Oak would be better for support timbers, doesn't mind wet/dry cycle. (Used for Lock gates for instance.)

 

[AndyT]

Do make sure that there isn't a rubber pond liner keeping the water in before anyone starts hammering poles into the bottom!

 

[Jacob]

Alder is traditional.

 

[SteveW1000]

Thanks for the advice, knew that Elm was used in locks but didn't know that it had to be kept wet. Can't easily use scaffold poles as it's got a Butyl Liner. Will see what the tree surgeons can find.

Got an interesting freebie coming up, a pair of replacement Oak Gates for a Grade 2 listed church. The boroughs conservation officer is going to order up the oak for the job. Needs to be an exact replacement and they've unusual wedged and pegged mortices will post up a WIP once the Oaks ordered.

Steve

 

[CHJ]

..... Can't easily use scaffold poles as it's got a Butyl Liner. Will see what the tree surgeons can find.
...

Square section 25Ltr Plastic drums make good floats for water edge support, even if water level drops they rest on the bottom without causing damage.

 

[Bigdanny]

Agree with Chas above, make it floating jetty.

 

[RogerP]

Greenheart (Lauraceae Ocotea rodiaei) is about the best for durability but where you could get it, what it would cost and whether it's FSC certified is another matter.

 

[marcros]

unlikely from the local tree surgeon...

If you cannot use scaffold poles because of the liner, is any form of post, whether timber or other, not going to present the same problem?

 

[Jacob]

unlikely from the local tree surgeon...

If you cannot use scaffold poles because of the liner, is any form of post, whether timber or other, not going to present the same problem?

Alder is traditional and is quite likely to be available if there are any rivers in your vicinity, though it may take a bit of tracking down.

 

[Phil Pascoe]

A pond and a jetty in a school? ............elf'n safety?

 

[woodbloke]

Greenheart (Lauraceae Ocotea rodiaei) is about the best for durability but where you could get it, what it would cost and whether it's FSC certified is another matter.

I agree, if you can get hold of some gash gh (from an old dock say) then the stuff is practically nuke proof, but it's hellishly hard and the splinters are toxic. I used a bit for the bottom of a plane and it's almost as difficult as lignum to use - Rob

 

[andersonec]

Then again you could use Alder.

Andy

 

[wills-mill]

Alder and Beech are (like Elm) only pretty sensible when fully immersed. Sadly they'll crumble at the water level in a couple of years where the timber is constantly damp. Oak and Sweet Chestnut would be favourites, if you're pestering tree surgeons try Robinia pseudoacacia (Black Locust in the USA, Robinia over here) which is a dense and durable favourite, otherwise have a crack at lengths from conifer hedges- Thuja, Lawson's Cypress (Port Orford Cedar (USA)), or Leylandii are all very under rated.