Diagonal lashing
Joins two poles that cross at an angle or tend to spring apart, such as braces. A timber hitch first pulls the poles together, then wraps go around both diagonals.
- a few minutes per joint
Explained simply
A diagonal lashing joins two poles that cross at an angle, like an X. Sometimes such poles do not quite touch, or spring apart because they are under tension. The diagonal lashing first pulls them together and then binds them firmly.
You start with a timber hitch that runs diagonally around both poles. It acts like a fist squeezing the two pieces of wood together. Then you wrap along one diagonal, then along the other – like two plasters stuck on crosswise. Finally come frapping turns and a clove hitch.
Careful: poles under tension can spring back when you lash or release them. Keep your face and hands out of the direction they could whip.
How it works
The timber hitch lies diagonally around both poles at the crossing. When you pull on the standing part, it closes and draws the poles together – that is its job, and that is why it comes first. Then come wraps in the same direction as the timber hitch, which hold the poles in that position.
The second group of wraps runs across the first, along the other diagonal. Together the two groups fix the angle so that the poles neither spring apart nor twist. Frapping turns between the poles tighten all the wraps. In frames, diagonal braces like these are what make a structure rigid – without them a rectangle would fold into a parallelogram.
How to recognise a good lashing
In a finished diagonal lashing you see two groups of several wraps each, lying crosswise, with tight frapping turns between them. The poles touch firmly at the crossing. When you try to move them against each other, nothing should give.
Every wrap should sit tight and lie beside the previous one, not on top of it. The timber hitch should have enough twists that it does not slip while pulling the poles together. At the end, secure the cord end with a clove hitch on one of the poles.
Typical mistakes and how a lashing fails
If you start without the timber hitch, you often cannot get the poles together – the wraps then just span a gap and loosen quickly. Another mistake is wrapping along only one diagonal; the joint can then twist in the other direction. And without frapping turns, everything stays looser than it needs to be.
Over time this lashing can also slacken, especially as the wood dries and shrinks. So check it regularly. Its load capacity cannot be generalised; test it carefully.
When it makes sense – and when not
The diagonal lashing is meant for bracing: poles that run at an angle through a frame and make it rigid. It is also the answer when two poles do not touch before lashing or spring apart under tension.
For right-angle joints loaded from above, the square lashing is better. Load-bearing structures for people do not belong in the hands of laypeople without expert assessment. Life-safety use only after proper training with certified equipment.
Safety: what to watch out for
Poles that are bent or pulled together under tension store energy. If the timber hitch slips while pulling them together, or when you later release the lashing, they can spring back. Keep face and hands out of the line of spring, and preferably work in pairs: one holds the poles, the other lashes.
Watch out for cracked or rotten wood that can break under tension, and for sharp branch stubs that chafe the cord. When cutting wood, local rules apply.
Step by step
- 1
Timber hitch around both poles
Tie a timber hitch diagonally around both poles at the crossing and use it to pull them together.
- 2
Wraps on the first diagonal
Make three or four tight wraps in the same direction as the timber hitch.
- 3
Wraps on the second diagonal
Make three or four tight wraps across them, along the other diagonal.
- 4
Frap and finish
Two or three frapping turns between the poles, then finish with a clove hitch on one pole.
Common mistakes
- Starting without the timber hitch so the poles do not come together
- Wrapping only one diagonal
- Forgetting the frapping turns
Quick view
Materials
Sturdy sticks / poles
Do not cut live wood where prohibited.
Rope
Never use unknown or damaged rope for life-safety purposes.
Thin twine
Low breaking strength – light loads only.
Suitable for
- Diagonal bracing in frames
- Poles that do not touch until lashed
Not suitable for
- Right-angle joints loaded from above – use the square lashing
- Load-bearing structures for people without expert assessment
Prerequisites
- Timber hitch
- Clove hitch
- Square lashing
Safety
- Poles under tension can spring back when lashing or releasing. Keep face and hands out of the line of spring.
How it works
The timber hitch around both poles pulls them together at the crossing. Wraps along one diagonal, then along the other, fix the angle; frapping turns tighten everything.
Advantages
- Pulls spreading poles together
- Fixes angled joints
Disadvantages
- A little harder than the square lashing
- Uses a lot of cord
Deep knowledge
Background
The diagonal lashing complements the square lashing where poles do not lie at right angles or spring apart. Scouting handbooks describe the two as a pair.
In frames, diagonal braces are what make a structure rigid; the diagonal lashing is the matching joint.
Common mistakes
- Starting without the timber hitch so the poles do not come together
- Wrapping only one diagonal
- Forgetting the frapping turns
Limits and risks
- Load capacity cannot be generalised; test carefully.
Material alternatives
Derived from material properties: a substitute must have all relevant properties. Observe the notes on the substitute.
- Rope
- Paracord (Not a climbing or safety rope.)
- Thin twine
- Rope (Never use unknown or damaged rope for life-safety purposes.), Paracord (Not a climbing or safety rope.), Accessory cord (Use only certified cord after training for life-safety purposes.), Webbing (tubular webbing) (Inspect knotted webbing before every use.), Jute or sisal twine (bought) (Low strength, absorbs water and rots – light loads and practice only.), Tree straps (Load only within the manufacturer's limits.)
Results come exclusively from structured entries. No improvised instructions are generated.
Sources
Boy Scouts of America: Scouts BSA Handbook
Diagonal lashing starting with a timber hitch