Cable Bracing Horse Chestnut

[RidArb]

Hi,

 

Had a look at some old bracing in a regular clients H.Chestnut today, it is an old feature tree in front of his house and has two braces that support one large co-dominant limb.

 

The limb in question has a large included union at the base and on inspection I thought that the bracing was excessively tight and has started to rust, as expected with older steel bracing.

 

I mentioned to him, it would be worthwhile to replace the bracing system for a cobra style system and reduce some weight out of the top of the limb to reduce the lever force of the limb, however, my concerns are that during the replacement, the removal of the old system could cause problems.

 

So am after thoughts on what people would do in a similar situation, hopefully pictures are attached, the client is looking to retain the tree as the primary option.

 

Many thanks

 

 

 

 

[beechhunter]

Hi ridarb i would say the weakest point on the original brace is the d shackle. For a start i would replace the d shackle with a longer one to see how much the tree moves when you cut the old one off. I would also go see the tree on a windy day to see how its moving (sounds daft) should give you more of an idea if the brace is correct or not. Hope this gives you some ideas. Pat

[treeseer]

I would go with your original idea of reducing lever arm. That may allow the original system to remain, as the reduced load can be supported by a cable even with its slightly reduced holding power. And the owner might not even notice 10% off with <8 cm cuts.

 

Some of the money that a cobra system would cost could then be invested where it will do some good--the roots!

Edited July 22, 2014 by treeseer

[colemanjessenz]

A nice light reduction then put in a static just above bracing leaving he old one in, I don't know how much good taking out the old stuff will do as you've said it may just cause problems .

 

 

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[Gary Prentice]

Neither the existing cable nor a new system may even prevent failure. Included unions often fail 'cupboard door', opening from on side and turning.

 

The existing tightness would be a concern. It may have prevented/reduced movement and impaired the development of reactive/strengthening growth. Removal could lead to failure and simply replacing with a system that isn't as supporting may not help.

 

I'd probably reduce enough to take the tension out of the cable, which doesn't from the photo's look too bad, and maybe consider bolting below the union. I saw loads of cables after the great storm that hadn't prevented failure but held the failed part up, that were a lot worse than that appears to be.

 

Are the bolts through and through or lags? Lags can pull out of timber that doesn't compartmentalise too well. Just something else to consider.

[RidArb]

Thanks for the responses;

 

There is a lot of tension in the bracing, its bow string tight at the moment, and agreed it has probably limited the reactive growth needed for the tree to strengthen the union itself, although it may have failed without it so who's to know...

 

The attachment bolts appeared to be lags with a full eye (as opposed to "J" lags) and there were only two bulldog clips on the join, I always thought 3 was correct, the end one on some is less than an inch from the end of the cable, if that makes sense, i.e. there is little room should it slip.

 

Do people think that the addition of a new brace above would be a waste of the clients money or is it prudent, knowing that the current bracing may be inadequate.

 

Thanks again

[RidArb]

I should add, the area underneath the tree is an old tarmacked farm courtyard, and that the limb in question is on the side nearest the house, should it fail, it would be touch and go as to whether it would hit the house. Also cars are regularly parked underneath the tree.

 

Just to add some context