Hardware for placing climbing anchors in trees

I have a Norfolk Island pine tree on my property that is probably 100 feet tall. After gaining some experience with a smaller podocarpus, I'm working on setting up the big one for roped climbing. I bought some 3/8" stainless hangers and have put 5 of them up on the tree, using zinc lag screws. After some trial and error, I find that if I drill a pilot hole with a bit as small as 1/4", I can still get the screw in with a wrench. (The wood is sort of a medium-soft wood, similar to a Douglas fir.)

Does anyone with woodworking experience and/or experience bolting climbing routes have any comments on what I'm doing and whether it makes sense? Should I be using a torque wrench, and if so, how much torque should I use? I feel like it's getting snug up against the hanger and then it starts to feel like it's about to go soft on me, as if I shouldn't go any farther or I'll strip the wood.

Tying webbing around the trunk, draping it over the branches, seemed like a pretty quick and cheap technique on the podocarpus, but the branches of the Norfolk Island pine are extremely slender. I'd also like to end up with something that will be safe to climb on for many years to come, rather than having to worry about nylon webbing gradually degrading in sunlight. What I'm doing right now with the Norfolk Island pine is definitely strong enough to hold 2 x body weight when I hang off of it in a pulley configuration, but ideally I'd like to have something bomber that will hold a whipper.

Is this above a cliff or are you climbing the tree? Why not just sling it or put bolts in the rock? 

You don't want to put too much torque on a bolt in a tree (without a nut on the back) because you will "strip" the wood and there will be very little holding the bolt in besides fiction. Expansion bolts in rock expand to have a lot of fiction, which you could try in wood but it'd likely crack the tree. Arborists and woodworkers put in bolts entirely through the wood with a nut on the back when it needs to hold heavy weight. 

To have an anchor in a tree that will be safe to climb on you'll need all stainless steel hardware with several washers. Without washers spreading the bolt head from the tree the tree will grow around your bolt eye in a few quick years. Also, trees are constantly full of water and chemicals and will quickly corrode non-stainless equipment.

Check out how high rope course builders go about it,

How long are the lag screws you're using?

There is a reason climbing gyms do not screw hangers into the wall. With a big enough lag 10” x 1/2”… maybe? But slings around the tree are such a better solution. You can even thread smaller webbing through some larger webbing for extra strength and double UV protection. Thar will hold a fall for 5 years atleast… as long as the squirrels dont get to it. But I would just use some 2” webbing and do 2 wraps around the tree kind of like a prusik, it will cinch up tight and only get tighter when falling. The branches should not be used directly, only to help aid the sling not slipping down the trunk. I also like the idea of looking more into how to anchor into the wood with bolts… but I have seen trees reject bolts before essentially killing the wood around the hole. Then the bolt just falls out. 

B DeMers wrote:

Is this above a cliff or are you climbing the tree? Why not just sling it or put bolts in the rock? 

Thanks for your helpful post! I'm climbing the tree. As described in the OP, the branches on this particular species are very skinny (less than an inch), so just draping a sling around the trunk, over the branches, would not be strong enough. This is a weird-looking tree from the South Pacific, with this surprising disproportion between the massive trunk and the thin branches.

You don't want to put too much torque on a bolt in a tree (without a nut on the back) because you will "strip" the wood and there will be very little holding the bolt in besides fiction.

Yeah, is there any way to tell for sure other than the feel?

Expansion bolts in rock expand to have a lot of fiction, which you could try in wood but it'd likely crack the tree. Arborists and woodworkers put in bolts entirely through the wood with a nut on the back when it needs to hold heavy weight.

The trunk is almost two feet in diameter, so drilling all the way through is not an option.

To have an anchor in a tree that will be safe to climb on you'll need all stainless steel hardware with several washers. Without washers spreading the bolt head from the tree the tree will grow around your bolt eye in a few quick years. Also, trees are constantly full of water and chemicals and will quickly corrode non-stainless equipment.

Good to know, thanks. My hangers are stainless, but I'd better replace the zinc screws with stainless, and add washers. Would the washers go under the hanger, or in front? If they went under it, I'd think that would have the effect of increasing the hanger's lever arm with respect to the screw, making it more likely to snap...?

Sam Skovgaard wrote:

How long are the lag screws you're using?

2"

Arborist here.

Best option, by far, is to just girth hitch slings around the trunk and replace them every few years. I do it for life support all the time. You don't need branches for it to work. It will cinch itself to the trunk easily with the bark of a Norfolk. Actually taking falls on it will be bad for the tree, though. The "veins" of a tree are directly behind the bark.

You have to drill all the way through if you expect your method to work. Put a blocker of some sort on the other side that way you aren't relying on the wood at all. We use a thimble with 3/8 steel cable when cabling trees together.

Drilling 3feet holes into a trunk while dangling by ropes is a real pain lol. 2feet isnt that bad. Start with a shorter drill and then use the 2footer once your hole is already 6-12inches deep. You'll want a rope lanyard to go around the trunk as a way to create leverage for yourself in order to press the drill into the wood.

Cole is correct that some trees can start rotting on the inside where you drilled. That's why we rely on pressure from objects outside of the bark. Trees don't like being drilled into. I don’t think a Norfolk would be problematic, but going all the way through is just safer. 

As for drilling through the whole tree, do you want it lined up on the center, or is it better to not run through the pith? Seems like centered would be strongest, but I don't know if that's a problem for the tree. 

How many holes can you put in a tree without doing too much damage? 

OP, Hownot2 has a few relevant test videos. There is one from 2020 pull testing various wood anchors, including lag screws. Also, recently there was a video break testing massive hangers that are designed for use on trees (to be loaded in tension for ropes courses, so not necessarily better for your purpose). The break tests included pulling a lag screw out of a real tree repeatedly.

Ben Crowell wrote:

 just draping a sling around the trunk, over the branches, would not be strong enough

Politely: What arborists here (and elsewhere, if you asked) are telling you is that yes, a properly rigged sling* around a trunk with no branches is strictly strong enough and is the correct way to solve the problem. Arborists don't always rely on branches or crotches; there are several ways to cinch an anchor around a bare trunk in such a way that you can use it as a reliable anchor.

*Not necessarily a nylon sling for climbing.

Shouldn't you just girth hitch long enough slings or cordalette around the trunk as you lead your way up and then take them down when you are done?  I've done that before, but not on the type or height of tree the OP describes.  

Honestly, I feel a bit bad for the tree. Are you planning on taking whippers on it? What the hell man?!

J C wrote:

As for drilling through the whole tree, do you want it lined up on the center, or is it better to not run through the pith? Seems like centered would be strongest, but I don't know if that's a problem for the tree. 

How many holes can you put in a tree without doing too much damage? 

OP, Hownot2 has a few relevant test videos. There is one from 2020 pull testing various wood anchors, including lag screws. Also, recently there was a video break testing massive hangers that are designed for use on trees (to be loaded in tension for ropes courses, so not necessarily better for your purpose). The break tests included pulling a lag screw out of a real tree repeatedly.

We always try to go through the center, but we are also considering that thousands of pounds of pressure will be present at times. Also, we are typically cabling trees that are already deemed potentially problematic; so, the drilling is considered a lesser of two issues. We only drill two times in order to cable something, so those holes are not going to kill the tree. Rotting of a tree is really dependent on what kind of tree it is. Some do better than others. Environment is a factor as well.

Right behind the bark is where all the growth of a tree occurs and 95% of nutrient transportation. So I’m not really bothered with the integrity of the wood in the center being compromised from the drilling. I’ve cut down many massive oak trees in Florida that were mostly hollow at the base.

It’s anyone’s guess how many holes you can put in a tree before you kill it.

I personally recommend that the OP gets a friction saver and some throw line. Get the friction saver in the tree and use that as a top rope anchor. Just attach your rope to the throw line and trade them out when you’re done. That way, only the throw line(and a burly friction saver) are in the elements. You can install the rope from the ground whenever you want to this way.

Making a lead climbing route on your tree will involve removing all the limbs on one side of it, making the poor tree very ugly aesthetically. You might get a splinter up your butt if you don't clear them for falls.

Norfolk's have branches every 12 inches, so it would be like climbing a tall ladder.

A laurel oak, pin oak, live oak, silver maple, and redbud are all trees that would make for much more interesting climbs and tend to grow in similar regions as a Norfolk

Not trying to be rude or anything. You do what you want to do with your tree. Just adding my .02 to try to help lol

Ben Crowell wrote:

2"

That's definitely not long enough.  As others have said, drilling all the way through is the safest, but I feel like somewhere in the 6-10" length range would be plenty strong to whip on, provided the wood you're drilling into isn't all rotted out.

That said, you're lead climbing a tree?  If so, inquiring minds want to know: why the hell would you do that?

Sam Skovgaard wrote:

That said, you're lead climbing a tree?  If so, inquiring minds want to know: why the hell would you do that?

For fun.

If you end up using slings for anything, spansets are the way to go for stuff that will be left outside.

@OP, there’s no reason to drill the tree at all.  DONT DO IT!  If you feel you must have a more permanent anchor/ climbing safety, get a Steel flip line cable or something similar attach around a strong joint in the tree or around the trunk itself being sure to place some rubber or felt cushions between the cable and tree bark.

I’ve used nylon slings with proper cushions under them for both our kids tire swings, no issues at all.   Healthy trees and good fun. 

J C wrote:

OP, Hownot2 has a few relevant test videos. There is one from 2020 pull testing various wood anchors, including lag screws.

Thanks for pointing me to their videos. The historical interview with Doug Robinson was very cool. But I went through a bunch of their videos and tried to find the one that had the part with wood screws, and couldn't find it. Any idea where it is?

Pete S wrote:

@OP, there’s no reason to drill the tree at all.  DONT DO IT!  If you feel you must have a more permanent anchor/ climbing safety, get a Steel flip line cable or something similar attach around a strong joint in the tree or around the trunk itself being sure to place some rubber or felt cushions between the cable and tree bark.

If they're $150 each, then that's going to blow through my budget pretty fast. I've currently got 5 bolts and will probably end up with 10+ anchors, depending on how high I dare to go up this tree.

Erik Strand wrote:

I personally recommend that the OP gets a friction saver and some throw line. Get the friction saver in the tree and use that as a top rope anchor. Just attach your rope to the throw line and trade them out when you’re done. That way, only the throw line(and a burly friction saver) are in the elements. You can install the rope from the ground whenever you want to this way.

I see. That's an excellent idea. It's definitely a drag having to lead or lead self-belay every time I want to get the rope up in the tree.

But I do still need a way to safely work my way up the tree on self-belay in order to get up to where I'm constructing this anchor.

Making a lead climbing route on your tree will involve removing all the limbs on one side of it, making the poor tree very ugly aesthetically. You might get a splinter up your butt if you don't clear them for falls.

I wouldn't really call it a climbing route. Maybe I should clarify, I don't actually intend to whip on any of the pro. I just have in mind the goal of making the pro so strong that it *could* hold a whipper. 

The tree leans toward my house, so the side I'm climbing is the back side, which we never see. I've bolted about the first 20 feet, and so far everything I needed to clear was dead branches. I'm just now getting up into the green, live branches. Anyway, I don't really need to clear out a whole 180-degree wedge of the tree. It's more like I'm cutting out one branch out of each tier, sometimes two.

Norfolk's have branches every 12 inches, so it would be like climbing a tall ladder.

That's sort of what it's like, except that the branches are slender and down-sloping. I'm not really using them much for holds. I've just been nailing pieces of wood on for holds. So the thing is not (currently) set up at all like a fun climbing wall where you climb it for the athletic challenge.

A laurel oak, pin oak, live oak, silver maple, and redbud are all trees that would make for much more interesting climbs and tend to grow in similar regions as a Norfolk

Having a huge mature oak tree on my property would be awesome, but unfortunately that's not what I have :-) I have a podocarpus that is climbable up to about 20 feet (after which the trunk gets slender enough that I don't trust it), this big Norfolk pine (which I guess will still get even bigger if I live that long), and also a pretty big ficus that used to be my daughter's tree-house tree.

Pat Light wrote:

Politely: What arborists here (and elsewhere, if you asked) are telling you is that yes, a properly rigged sling* around a trunk with no branches is strictly strong enough and is the correct way to solve the problem. Arborists don't always rely on branches or crotches; there are several ways to cinch an anchor around a bare trunk in such a way that you can use it as a reliable anchor.

*Not necessarily a nylon sling for climbing.

I see. Do you know of anywhere that I can read up on the technique so I can understand how it's done properly and think through whether it would work for me? The thing that I don't like about nylon slings is that as soon as you put them up, they're going to start to degrade. I don't want to have some kind of new maintenance task that I have to do, freshening the slings every so often, and I don't want to have to guess whether the slings are old and UV-damaged enough to have lost their strength. Of course, an arborist isn't leaving the slings up, so they don't have this issue.

Below are some photos of what I have so far. This is essentially what I had *before* starting this thread, so they don't yet incorporate almost any of the useful feedback I've gotten.

Above is my setup in the podocarpus. The start of the climb was hard, so I added a few wooden steps. There are red webbing slings tied around the trunk and over the branches (should have made these girth hitches so they wouldn't depend on the branches to hold). Near the top are the chains of my toprope anchor, which are backed up with slings on multiple sets of branches, plus an eye bolt (which in retrospect isn't strong enough to add to the anchor's strength).

Here is my ground anchor for the Norfolk pine. The tree is a smaller nearby one. The spaniel hasn't learned to belay yet. The anchor is redundant, using a 1/2" stainless hanger on the left, backed up with a two-wrap Prusik as suggested by folks in this thread. The Prusik should be bomber, since this tree widens and forks above this point.

Here is my monster Norfolk pine. There are four 3/8" hangers to the right of the rope. Locking biners are clipped into the top two bolts. This is about 20 feet worth of the tree. I think I should be able to double the height.

Chain or cable with a hose protector over it would be better, animals may unknowingly chew through fabric slings.  As long as the branches aren’t at too acute of an angle,or dead, it would be very hard to shear them off with the sling wrapped around the trunk.

https://youtu.be/OZwY0LZS4qU

Hownot2 vid

Loose loop of chain around the top with a lag through the chain(on the back) as a backup. Solid and permanent.