Guying question

[Dan Flinn]

Hi all,

I am bidding on a job that will involve guying a large (60') red oak. First of all, the tree is on a 12% (or so) slope and has a slight downhill lean. It has some normal dieback and what appears to be a small basil cavity - far from a removal recommendatoin, IMO. If the tree falls, it will fall across a driveway. The customer has concerns about this and wanted options. I sold him on the "extra support, but not a guarantee....", now I need to know how to do it!

I have installed steel cables before, but guying is new. There are several trees the same diameter uphill, about 50-60 feet away that will provide excellent anchor points.

My plan is to install 2 guy wires about 45 degrees apart, uphill, almost horizontally, to the trees I mentioned before.

How do I estimate the strength of cable needed? My initial thoughts are 1/4" High strength (6650lbs). Sound about right?

Thanks in advance for your thoughts!

Dan

Oh, yes, I have ordered the standard, but I'd like to arrange my thoughts before it gets here

 

[Kevin]

If I was doing something similar on a large tree where wind and ice might be a factor I would use 10M strand with preforms, through bolt, a good earth anchor and a guard so people won't sue you when they walk into it.
Keeping in mind I work on the line.

 

[treeman82]

let's hope the server will let me do this. I would suggest that you set at least 2 sets of cables. Also, reduce the crown on the tree by about 20 feet in order to remove some mechanical advantage. As is you are just prolonging death.

 

[John Paul Sanborn]

Is there any soil heaving around the base of the tree?

Does the lean apear to be from growth or throw?

Have you calculated the weight of the tree?

My gut reaction is that the system you envision is under designed for a 60ft oak, even if you do do some corwn reduction.

Hevier cable and more of them

 

[treeclimber165]

Where's Geofore on this thread? He's our resident engineer!
You need to figure out how much load you are supporting before deciding what strength cable to use (and how many).

 

[TheTreeSpyder]

.... and the anchoring, of course if roots are already moving like JP indicated it might be a little late......

Might just reduce crown, side that pulls in the direction of the lean, not that weight which already fights the lean.

 

[murphy4trees]

In cabling (or guying) the HIGHER THE BETTER.....
For crothes with included bark the rule of thumb is 2/3 the height from crotch to tip.. I'll go 4/5 or even higher when practical... the added leverage is worth it. I don't worry about drilling into smaller wood as long as it is strucurally sound.

Tree to tree may be the way to go on this one.. multiple cables. And leave them loose, especially since it's winter. Hit these people up for some serious cash and do the job right!!!

I've cabled alot of big trees and only ever guyed 1. So I would do some more research before proceeding.

82 .... are you recommending turning this 60' red oak into a 40' red oak?

God Bless All,
Daniel

 

[geofore]

guys

You need to give the DBH? not just how tall. With the 1/4" wire rope you are looking at the same end result as Toys-R-US roofing, catostropic failure when loaded, under designed. The spread of the tree is? Biggest factor is how far the tree moves in the wind in full leaf so you know how much slack should be in the guy so it does not load prematurely. No garantee; the tree going over in high winds would be considered an "Act of God". At best you will be able to set the guys to cause the tree to arc out into the direction of the driveway if and when it goes(extreme winds and extreme rains) by the way you set the guys to load and fail. Guy1 fails allowing the tree to fall, Guy2 holds allowing the tree to arc toward the driveway(the intended target area)What is the distance to the objects you don't want to hit if the tree would fall? What is the actuall hieght of the tree? I would not want to do a crown reduction if the tree is not tall enough to hit the house or garage or reach the driveway or swimming pool. A picture would be nice.

 

[Kevin]

Now if you really wanted to dazzle them you could guy, tension, undermine the tree ...leaving a root ball, tension, straighten the tree and backfill leaving the guy in place.
Would it work with a large tree ... I have no idea but I don't see why it wouldn't.
We do it with loaded poles all the time but they are without root!

 

[Kneejerk Bombas]

I like the plan as Dan originally presented. No crown reduction, no soil excavation, no telephone pole guy wire. THe tree will most likely do well on it's own, the guys just add a little suplimental support if the need arises, they don't support the entire tree. Two 6500 lb cables would be more than enough.
When a tree has structural problems that can best be helped by adding more wood, removing leaf surface area by crown reduction does exactly the opposite. We all know a healthy vigorous tree comes back from injury faster and better than a tree that just lost a large percentage of the crown.
Undermining a mature tree will result in root loss, period, that only increases the chance of it falling, and from a biological standpoint weakens the tree.
If I were to offer any other suggestion, it would be to incorporate some form of shock absorber, perhaps using a Cobra cable.

 

[geofore]

Mike

The last large white oak I took down here had 362 rings so it was here when George Washington came through. 7 degree lean down hill on a hillside for all those years without guys to hold it. The roots held it just fine but lightening took off every leaf and nearly all the bark or I would not have been asked to take it down. I don't know if if this tree needs guys or the coustomer wants them to feel secure. I'd have to see the tree. If it does need guys I'd set it to follow a planned failure as above, risk lowered by planning the landing should it fail.

 

[Joe]

My thoughts: use ansi A300 guidelines for cabling, bracing, and guying + the best management practice (I.S.A. publication) publication of the same title as the A300 guidelines to help interpret the standards.

http://www.google.com As usual, one ought to be able to turn up more information with the search engines.

Using the standards will help cover the legalities associated with the risk of taking on such a project. It'll say you are aware of the standards and followed them in case of litigation.

For the heck of it:

http://www.isa-arbor.com/AboutISA/ethics.html

Joe

 

[treeman82]

Daniel, as we have been told, the tree is rotting away at the base. Without seeing the tree and its present branch structure I couldn't really give a number for height reduction. However I took a class and the professor showed us slides of his company doing just what I said. Only a few big cuts, don't do anything else. The trees he did that to look just fine now. And really all he was doing was prolonging death and mitigating a hazard.

 

[murphy4trees]

It's always been a tough judgment call when there is a structural problem.... how much weight to take off??? knowing that the less weight, the less potential for failure in the short term, and yet as Mike has clearly posted the less weight, the more damage to the trees overall health and ability to sustain life, resist decay, add new wood etc..
In the past I would prune as your prof suggested... a few big cuts to get the wood weight out of the tree, and go for the wood that has the most leverage relative to the structural defect, which is usuallt the top of the tree.... When doing so I was really careful with the target cuts. Empirically, most of the trees I've done this too over the past 20 years have done pretty well. So I might think as your professor does, that it is a good practice....
Yet, I've changed my mind, mostly from reading posts here... 20 years isn't much in the life of a tree... So what looks good from my limitted perspective, may in fact be harmful.
One of our primary responsabilities as arbos is to protect people and property, so how I prune is very much effected by the location of the tree relative to roads, structures etc.. So that is another factor to balance out... do I do what is best for the tree or whatkeeps people the safest. If the tree isn't a threat to anything, and the owner would like to preserve it as long as possible, I would tend to go with Mike's perpective that less or even no pruning is better.
And after 20 years of watching storms blow trees down on houses I recommend removal more than I used to.
God Bless All,
Daniel

 

[Joe]

http://www.isa-arbor.com/consumer/mature.html

I think Mike M. is simply expanding on the philosophy in this on-line brochure. Notice what is said about the pruning of mature trees.

It looks as if Dan F. is a making a judgement call using his experience backed by the more current information.

Joe

 

[Dan Flinn]

Hi all,

Thanks so much for all the info! The picture that Mike Maas posted is what I had in mind, with two guys.

As is the case most of the time with these questions, I didn't provide enough info in the beginning.

The tree is 34' DBH. There is no evidence of uprooting, the lean appears to be phototropism. The downhill lean is so slight that it might have been my perspective on the hill. There is some dieback of lower limbs, I believe, due to the forest surrounding. It is not a wide spreading oak, the crown has been shaped by the forest. The target is a driveway, a section of backyard inhabited by dogs, and some landscaping. This job is definately a customer driven "keep the tree around as long as possible"

I didn't say, but I did plan to do a light crown clean of the lower dead limbs and 3" and larger in the crown. I didn't plan on doing a crown reduction.

I will take the advice given and bid the job a bit higher than I originally planned.

I read some city specs I found on line that recommended not anchoring lower than 10' on the anchor trees. Does that sound familiar? I think that higher is better, but there must be a point too high. Honestly, I had just planned to anchor about 15 to 20 feet up. Remember that the anchor trees are uphill about 40 - 50 feet from the base of the oak. 15' up the anchor trees will make the guys almost horizontal after installation.

This will be done in a couple of weeks and I have more work to do at this location, so I will try to get pictures.

I'm glad to have this site as a resource! All of your input is appreciated!

Dan

 

[Tom Dunlap]

There is good engineering information availalble about guying systems. You need to source from better places than us students here.

This has been a good source for me for many years:

http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/5-125/fm5-125.htm


I would be reluctant to back guy a tree like Mike M. illustrated. This puts loads on the anchor trees that aren't "normal"

Like Joe suggested, use Google as a resource for this information, not AS.

Tom

 

[Kevin]

Mike,
I spoke with the Army Corps of Engineers and they said it could be done by removing the earth from beneath the tree.

 

[Kneejerk Bombas]

Originally posted by Tom Dunlap

I would be reluctant to back guy a tree like Mike M. illustrated. This puts loads on the anchor trees that aren't "normal"

Like Joe suggested, use Google as a resource for this information, not AS.

Tom

What do you see as a possible problem(s) with guying as I illustrated?
I see the trees uphill as less important and the attachment points larger in diameter and strength.

In regard to not using AS for information on aboriculture, I disagree. It should not be your only source, but it's a good one. Using Google has it's pitfalls too, any information needs to be carefully scrutinized for source, age, content, and author, among other things. There is a lot more misinformation on the web, than information.

 

[Dan Flinn]

Well, guys, I enjoyed the learning experience. I bid $575 for the work and he decided to pass. I've been a little slow, but I thought this was a good price. Heck, the cost of the supplies was about $125!

Anyway, I did learn a lot and will be better prepared for next time.

As for using AS for my only resource, well......don't take it personally, but I have checked many resources. AS is only one source, but I do put a lot of weight on the information I gather here, and I use it wisely. One doesn't stay in this business long doing things he's not sure of.

Thanks again,
Dan