Green Building Forum - Tanalised timber

Tanalised timber

RobL — Thu, 18 May 2023 07:34:09 +0100

Posted By: WillInAberdeenFarms round here use fenceposts where the pointy end is dipped into bitumen to just above soil height, maybe something like this, or a homebrew version
https://www.tuffdip.com/solution.php

We have a bike store with several posts supporting, concreted into the ground. I bitumined the end of the posts with paint on cold applied stuff. The hole has 50mm of gravel at the bottom before putting in the post, concrete, then even a bit of flaunching to discourage water pooling next to the post. I also drilled a small hole in the post, injected in wood preserver, sealed up the hole. Probably been there over 10 years, no sign of rot.

In another location I used the same wood(untreated oak), no bitumen or gravel or preserver, rotted away in 5 years, snapped at gnd level.

Tanalised timber

Peter_in_Hungary — Thu, 18 May 2023 10:39:40 +0100

I use false acacia (Robinia pseudoacacia) on the farm and all cut from my own forest. Posts are de-barked, sharpened and then banged in the ground with a post hammer. No treatment and I get between 10 -25 years from a post. We have sandy soil.

Planks cut from the same wood last equally as long.

Tanalised timber

fostertom — Thu, 18 May 2023 12:10:02 +0100

Wow you're lucky - looks like an excelent timber and a pretty tree. 'False Acacia' to UK gardeners.

Tanalised timber

WillInAberdeen — Thu, 18 May 2023 12:26:09 +0100

Sure it's ok in Peters management, but don't be encouraged to plant it in UK.. invasive species, threat to native woodland, toxic to humans and wildlife/livestock....

https://invasiveplants.eu/en/invasive-alien-plant-species/false-acacia-black-locust-robinia-pseudoacacia/

So which is best for environment - bitumen on native timber, or black locust wood - who knows?!

Tanalised timber

Peter_in_Hungary — Thu, 18 May 2023 15:18:11 +0100

Posted By: WillInAberdeenSure it's ok in Peters management, but don't be encouraged to plant it in UK.. invasive species, threat to native woodland, toxic to humans and wildlife/livestock....

Yes it is invasive here as well but fairly easy too control. It doesn't seem to be toxic to the livestock as they will eat the leaves without ill effects.. Very good for honey production - bee keepers can get up to 50% of their annual crop from the 2 - 3 weeks of acacia blossom. It fixes N in the soil as well. Whilst not native it is a very important wood here.

Tanalised timber

djh — Thu, 18 May 2023 18:41:19 +0100

Both the RHS and Gardeners' World have it as suitable for gardens, although it's too large for most. GW says "Robinia has no toxic effects reported." whilst RHS says "Potentially harmful - Harmful if eaten, skin irritant. Wear gloves and other protective equipment when handling"

Tanalised timber

WillInAberdeen — Thu, 18 May 2023 19:07:03 +0100

Wasn't it the gardening establishment who also thought that Japanese knotweed, Rhododendron, Himalayan balsam, and grey squirrels would all look nice in their gardens? Just say no to importing invasive species :-) https://scottishwildlifetrust.org.uk/2019/08/invasive-garden-escapes/

https://www.poison.org/articles/are-black-locust-trees-toxic-221 suggests that humans are not likely to ingest the toxic parts, but will get ill in the rare cases that they do. Worse for horses, apparently.

Tanalised timber

Jeff B — Sun, 21 May 2023 14:27:46 +0100

As mentioned earlier in this thread, herewith a photo of the concrete gravel boards we are using for edging the lawn. Hopefully should last a lifetime so no need to replace, just a lick of paint every 5 years or so. In the grand scheme of things not a lot of concrete used I guess. Also not likely to be damaged by lawnmower!