Treehouse Support Elements
How to fasten wooden beams to the tree!
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The treehouse for your family and friends should be anchored as securely as possible in the tree. We will show you how to attach your wooden beams and the supporting elements made of them to the tree, by using our Treehouse Screws.
On the page “Platform Constructions” you will find further examples of how you can build a complete platform from these supporting elements.
1. Basics – The right timber for platform construction
The construction timber should be suitable for outdoor use, as it is freely exposed to environmental influences (rain, humidity, moss, …). Woods such as larch or Douglas spruce are best suited for all exterior treehouse parts – these are light, have sufficient strength and can be processed well!
In our treehouse carpentry, we always use untreated, domestic larch on the outside and spruce or pine in the dry interior.
If the wood is screwed directly to the tree or lies in the splash area on the ground (e.g. stilt base or stairs) it should be particularly resistant (oak, Robinia, etc.). Disadvantages of these noble hardwoods are the high costs, the heavy weight and the difficult processing (effort, tool wear).
The timber must be dimensioned in such a way that it can withstand the “worst case”:
- Maximum load due to storm, snow, party guests
- Defects in the wood (cracks, knots, rotten front wood at the end of the beam due to water contact).
- The wooden beams must not bend, long struts must not buckle.
- The narrow side (width) of the support beams should measure at least 6 cm (2.4 in), so you have enough space for screwing.
- The height of the platform beams should be at least 12 cm (4.7 in)!
- At Baumbaron, for example, we often use 6 × 12 cm (2.4 × 4.7 in) beams for the platform; and 10×10 cm (3.9 × 3.9 in) beams, larch, for the supporting structure.
In contrast to structures on the ground, we often have alternating loads (wobbling, swinging, leverage and torsion) in the treehouse:
- Classic carpenter joints (lap joints, etc.) should be avoided, as these weaken the cross-section of the beams and are pooling points for water – work better with smooth joints and lots of screws.
- Use long wood screws, partially threaded, galvanized, ø 6–8 mm (0.24–0.31 in).
- Screw heavily stressed areas more often
- Very heavily stressed joints are reinforced with angle plates or PU glue
Bracing: Square passes – triangle persists!
This is one of the most important construction rules in building – no matter whether horizontal or vertical load, no matter whether supporting structure, floor, walls, or roof – to prevent your surfaces from tilting you have to brace them with triangles.
TIP: Use diagonals and struts to form triangles!
2. Consoles as lateral Support Elements
Brackets are versatile and suitable for small supporting structures. Several brackets can be used to build small platforms on a tree. There are two variants:
GTS Side + Wood Screws
If the beam is screwed directly to the tree, the rough bark should be removed and the wooden beam adapted to the shape of the trunk. Since the beam lies directly against the tree, there is a risk that moisture will collect and be absorbed through the front wood. To prevent this joint from rotting prematurely, you should use sturdy wood such as oak, Robinia or very slow-growing larch.
Advantage of the construction with Strut Support Safety:
- Easier assembly
- Height-adjustable at a later stage (if strut sags under load)
- No water accumulation
- Tree can better wrap around bolt
Application area of brackets:
- Small loads
- Mini platform
- Easy mounting
- No matter if tree is inclined
- Branches can be easily bypassed
- 6 mm notch in wood (e.g. with hand-held circular saw, power saw)
Note (especially in softwood):
- Tensile load on upper screw GTS Side with large lever (pulling force).
- Horizontal / lateral load on GTS Side should not be too high.
- It is best to work with brackets / screws opposite each other so that the construction cannot tip over.
Wooden bracket mounted on the side of the tree – Pulling Force on upper GTS Side
Bracket mounted to tree – Avoid horizontal side forces on the construction!
3. Triangle Construction
Let’s move on to the most important supporting element in treehouse construction – the “triangle” or “tribeam construction”!
A supporting triangle of wooden beams carries the platform of treehouse.
Mounted only with a fixed bearing, the beam would rotate around the screw axis.
The triangle is formed from two additional Struts held together at the bottom by a “Bracket” – the load is transferred into the trunk via both Screws!
The triangular construction is inherently rigid and cannot tilt sideways. Nevertheless, the triangle remains easily rotatable around the trunk axis – thus wind fluctuations are dampened.
The advantages of triangular construction are:
- Triangles are immovable and rigid
- The platform can cantilever widely / protrude laterally
- The screws are below each other, fewer vessels are cut through
- No opposing screws – the trunk can be slightly thinner
- 3D triangles allow for very large platforms, whether in one or more trees
- A lot of freedom in design!
- Course of the struts can interfere
- Attention with struts near the base of the trunk / ground, here the tree is often strongly curved (more on this below)!
Examples: 2D – Triangle Constructions
For large loads, you can also brace the triangle with extra wood struts – this prevents long struts from bending and buckling; the load is distributed more evenly across the beams.
Use wooden wedges to reinforce your upper strut connection!
Such “roof constructions” are also possible, make sure that the struts are connected super-strongly in tension, preferably with additional steel sheets.
The V-Bracket has the advantage that the strut angle is variable: you can choose between 60° steep and completely open!
The steeper the angle, the more vertical load is possible!
Attention with very flat angles: the lower screw is loaded laterally by the strut (horizontal compressive force across the wood grain) – laterally, the wood withstands less than longitudinally to the grain!!!
You can design all imaginable shapes – let your creativity run wild!
The V-Bracket also allows for triangles that cantilever out on one side – again, watch out for the greater horizontal load on the lower screw, in which case it would be pushed away to the left!
If your tree is leaning sideways, this is not a problem – make sure the crossbar is in the water and simply move the fixed bearing (top) to the left or right.
If the tree is tilted forwards or backwards, you must be very careful that the Supports still fit on your shaft. If the tree is tilted too much, one of the Supports will float in the air!
Solution 1 – Inclined trunk: You can get closer to the trunk with a GTS Friend, which has no cylinder like the GTS Allstar.
Solution 2 – Inclined trunk: You can also turn the “Bracket” around and remove some of your wood to get closer to the tree.
Solution 3 – Inclined trunk: Another good solution is to double up your wooden beams!
Examples: 3D – Triangle Constructions
3D triangles are used for large, heavy, and wide cantilevered platforms. In addition to the lateral braces, they also have braces to the front and/or rear.
Additional braces can be attached to both the V-Bracket and the 45°-Diamond Bracket; however, the Diamond Bracket is more suitable because it has a solid back wall that can better absorb the pressure loads.
How to build a complete platform out of these elements, you can see in our article: “Platform Constructions in 1, 2, 3 and 4 trees”
Large 3D supporting structure made of wooden beams for treehouse platform, by baumbaron GmbH, at a height of 8 m in an oak tree
Dimension of triangular beams
- Depending on the cross-section and load, the wooden beams may protrude / project laterally.
- The vertical spacing of the “GTS Screws” should be 1.5–2.5 m (59–98 in).
- The strut cross-section should be at least 8 × 8 cm (3.1 × 3.1 in).
- The upper cross-beam should be at least 8 × 12 cm (3.1 × 4.7 in).
- The wooden beams are always installed upright / on edge!
Orientation values for the beam height h:
- Length 3 m (118 in) = 8 × 12 cm (3.1 × 4.7 in)
- Length 4 m (157 in) = 8 × 16 cm (3.1 × 6.3 in)
- Length 5 m (197 in) = 10 × 20 cm (3.1 × 7.8 in)
You can find more rules of thumb and tips on timber for your treehouse in our FAQs.
4. Reinforcing Elements – increasing the load-bearing capacity
When do you need supporting elements?
- Your treehouse is getting very big & heavy – your tree screws are reaching their load limits!
- The wood of the tree is soft (poplar, willow, spruce, pine, fir, Douglas fir).
- You notice during or after assembly that parts of the platform wobble or tilt.
- You subsequently extend your treehouse or the platform.
There are two ways in which you can increase the load-bearing capacity and thus safety:
1. Reinforce Tree Screws directly
2. Reinforce heavily used parts of your platform
a) With additional struts
Braces can either be planned directly into a “3D triangle construction”, or they can be added later where the platform sags and wobbles.
In our Shop, you will find a wide range of solutions:
- You can attach single struts with the Strut Support Safety – you can also use small logs from ø 20 cm (7.9 in)!
- Multi-struts: You can slide one or more Strut Support GTS onto the shaft of our large tree screws.
- You can also screw wooden struts directly onto existing struts.
- Or you can use elegant, thin tubular steel struts instead of wood.
b) Rope suspension from above
If the struts under the treehouse get on your nerves, you can also support your platform with a rope from above. Make sure you find a stable branch or a thick branch where you can attach your “tree harness”. Remember that the rope itself can cause your platform to sway in the wind.
Smaller loads up to 500 kg can be attached directly to the GTS Safety.
A load-bearing steel or Dyneema rope should have a minimum diameter of ø 8 mm (0.3 in) for larger loads.
c) Concreted posts
If there is no nice way to support your swaying platform on the tree, you can concrete an artificial support into the ground.
We always recommend Robinia or natural acacia round timbers ø 10–15 cm (3.9–5.9 in)! These can be placed directly in the foundation, are extremely stable and look natural!