Bracing and cabling a tree

[P.cols]

Hi all,

 

Has anyone had any experience bracing and cabling a tree?

I’ve been asked by a client to prolong the life of a Chinese Elm that has started to fail at the main union where the trunk splits into two.

My thoughts are to drill and bolt the tree through the union and then install a static cable brace (like a cobra brace) within the crown.

 

Has anyone done this before? Has it been successful?

Thanks

 

[Jake Andrews]

Hi all,

 

Has anyone had any experience bracing and cabling a tree?

I’ve been asked by a client to prolong the life of a Chinese Elm that has started to fail at the main union where the trunk splits into two.

My thoughts are to drill and bolt the tree through the union and then install a static cable brace (like a cobra brace) within the crown.

 

Has anyone done this before? Has it been successful?

Thanks

 

 

Hi,

 

Yes, everything you are describing is plausible. But, given the species that you’re going to be doing this too, it may require some pruning aswell, depending on its size. Chinese elms are very ‘end heavy’ trees with much of their foliage near the ends giving a long arm lever effect. It may be prudent to end weight reduce some of the heavier limbs to further reduce the stresses on the union you are trying to support.

First, install ratchet strap in the tree at the height of where your static brace will be installed and pull the limbs together so that the ratchet strap is slightly taught and supporting the limbs.

Then, install your rod brace on the unions (1,2 or 3 depending on the size of the split but do not make the rods parallel with each other) and after that, the static brace before removing the ratchet strap.

Chinese elms are notorious for splitting main unions and I did my fair share of bracing them during my time in Melbourne. Beautiful trees though.

Do you have any pictures of the onion?

[Khriss]

I would avoid drilling trunk ( infection route) but hard to say without pic. Cable bracing crown worthwhile, abd as Jake says, bit of end weight reduction to ease loading. 

 

 

 

[MattyF]

Nothing wrong with rod bracing , I've never seen an infected tree?? I've seen screw bolts from cables pull on woods that the Tannin in woods like oak and chestnut after they reacted badly and not callus though..... I would use cobra for those species but elm seems to swallow any thing it comes in to contact with.. bracing ideally wants to be 2/3rds up the limbs being braced.
But back to rod bracing I've seen and the ones I have done have been very successful over the years.

[MattyF]

I would also add that rod bracing young and vigorous oak and chestnut will still work, it seems though that older specimens from my experiences don't seem to have the ability to callus over quick enough and they react with the metal.

[P.cols]

Thanks everyone really helpful comments [emoji1303]
Hope this isn’t a silly question but for the rod bracing do I just use threaded bar with nice big washers and nuts, m12 or thereabouts?

[Steve Bullman]

Venetian style bracing. Don’t think these trees are going anywhere! Looks like cobra or boa 

 

 

[Joe Newton]

On 26/08/2021 at 11:02, Khriss said:

I would avoid drilling trunk ( infection route) but hard to say without pic. Cable bracing crown worthwhile, abd as Jake says, bit of end weight reduction to ease loading. 

 

 

 

Any pruning wound is a possible infection route. A large tear out wound would be too. Lesser of two evils.

[Mark J]

6 hours ago, Joe Newton said:

Any pruning wound is a possible infection route. A large tear out wound would be too. Lesser of two evils.

Pruning wounds don't tend to extend into compartmentalised areas of fungal activity.

I agree that it's the lesser of two evils though. 
 

[Andrew McEwan]

As another option for a tree you might  otherwise rod brace, for a lo- ish static brace lately I've used aircraft grade steel cable looped round the stem, but with dead oak heartwood spacers/load spreaders positioned vertically, so there is minimal compression and disruption to the cambium, same idea as you'd use on a retained tree that was a winching point on a forestry job. Avoids big drilling for a rod and you can see the condition of the cable over time, oldest install is only three years old though but seems to be working well so far. And pre-load union first as Jake says with rachet straps, on bigger trees the Stein rcw3001 (or any winch bollard) has been brilliant instead of rachet straps at winching a union together just with a tied off rigging line and pulley.