In our online shop, we sell exactly these fasteners for a permanently secure connection of tree and treehouse. Here you will find a rough overview of our Treehouse Screws and the matching Accessories. You can find more details on the product pages.
6 Treehouse Screws
1. Dimensions of the Screws in comparison
Low tool requirement due to optimally matched products!
- All GTS Screws (except the small GTS Safety) are pre-drilled with the same ø 36 mm Auger-Bit.
- All GTS Screws can be screwed into the tree with the same 1″ Ratchet + 46 mm nut.
- For the GTS Allstar, the hole for the cylinder (Forstner-Pin Combo) must also be pre-drilled.
- The GTS Safety is pre-drilled with the ø 24 mm Auger-Bit.
2. Field of application of the GTS Screws
In our shop you can choose from 6 Screw models, each Screw has its own special area of application.
The GTS Allstar is our flagship and the most frequently used Treehouse Screw. It is the best choice because it can carry enormous loads both vertically and horizontally – in softwood (spruce, fir, pine, etc.) it can reach a vertical load capacity of up to 2.5 tonnes. In combination with Strut GTS + or Cable Suspension, the GTS Allstar can carry 6–8 tonnes in hardwood (oak, beech)!
Because of the large cylinder, it should only be installed in trees ø > 35 cm (14 in).
“In our ‘Baumbaron’ carpentry workshop, we always use the GTS Allstar as a base for our tree houses. The other Screws then expand the scope!” – Vitus W.
The GTS Top specialises in medium vertical loads on small trunk diameters ø < 35 cm (14 in), where the GTS Allstar would be oversized. Instead of the large cylinder, it has a small support plate and is therefore gentler on trees than the Allstar. This advantage is particularly effective in hardwood. In softwood, on the other hand, the load-bearing capacity decreases considerably, and here it is only suitable for smaller projects.
The Friend is our helper for light loads. It is often used as a lower anchoring point for tribeam constructions, tree swings and auxiliary constructions. It should not be loaded too much in soft wood!
The GTS Side enables the attachment of laterally projecting wooden beams to the tree and is therefore ideal for smaller platforms, landings and stair constructions.
The GTS Free is a slimmer stainless steel version of the GTS Friend that comes without Accessories. It is ideal for the smallest platforms and children’s playhouses < 10 m² (110 sq ft) where a small budget must be considered.
The GTS Safety is a complementary Screw for rope fixings, awnings, fairy lights, etc.
3. Load capacity of the Screws
The picture shows one of our numerous load tests, here in the laboratory of the Munich University of Applied Sciences (back in 2015).
The load capacity of the Screws depends on the following factors:
- Individual tree (tree species, growth form, strength, age).
- Wood quality in place of drilling
- Lever arm (where the Screw is loaded)
- Direction of load (vertical / horizontal / compression / tension)
- Type of load (static, jerky or swinging)
- Quality & accuracy of assembly
Vertical load capacity:
The vertical load capacity of our GTS Screws is shown in the graph. The shown values refer to a vertical load acting in the mid-section of the shaft.
Horizontal load capacity:
The horizontal / lateral load capacity is approx. 1/3 of the vertical load capacity.
The pull-out resistance, i.e. the force required to pull a screw horizontally out of the tree, is approx. 300 kg (660 lbs) for large tree threads in softwood and approx. 500 kg (1100 lbs) in hardwood.
Load capacity of the GTS depending on lever arm and pivot point
In addition to the wood properties, the lever arm in particular has a great influence on the load-bearing capacity of the screws. The lever arm is the distance of the pivot point to the load application point (centre of the support).
The larger the lever arm, the lower the load-bearing capacity of the bolt, i.e.: the closer the beam is mounted to the tree, the higher the load-bearing capacity!
With normal loading, the support beam should be approximately in the middle of the GTS shaft. With high loads, it is better to bring the support a little closer to the tree. With low loads, on the other hand, the support and beam can rest further out on the GTS shaft – the tree then has more room to grow.
Important note: The load capacity of the Screws depends strongly on the individual tree and its wood! The load values are only guide values – a safety factor >2 should always be calculated, i.e. instead of 4 tonnes load capacity in hardwood (average value of our tests), the GTS Allstar should only be loaded vertically with 2 tonnes!
The Accessory parts are the links between the tree screw and the wooden beam. They are attached to the large GTS models with shank ø 40 mm: GTS Allstar, Top, Friend.
(The smaller Screws, Side, Free & Safety, do not need accessories).
1. Supports and Distance Rings
The main elements for fastening the wooden beams to the GTS bolts are supports, these are pushed onto the shaft of the GTS.
Static supports are used for strong, immobile trees. Dynamic Supports are used for thinner trees that are susceptible to vibrations.
2. Triangle construction with Brackets
The Triangle Construction is a frequently used Support Element. The Screws are mounted one below the other on the trunk.
The Tribeam Construction offers the following advantages:
- The span (supporting surface for the platform) is considerably increased.
- The triangle is inherently stiffened and cannot tilt.
- The triangle can be freely dimensioned. The larger, the more stable.
- Screws that lie below each other have the advantage that fewer water and nutrient lines are damaged (vessels in the trunk run vertically).
- The trunk can thus be somewhat thinner.
45° Diamond Bracket
Our Struts open up additional possibilities when building your platform. You remain flexible – mount several Struts on a GTS or individual independent Struts. The beams can be firmly clamped with the height-adjustable plate. Instead of thick wooden struts, you can also mount elegant steel struts!
Strut Support Safety
Strut Support Platform
4. Reinforcement of the GTS – Maximise the load-bearing capacity!
This makes sense if:
- the GTS is overloaded (too heavy a tree house)
- your tree is very soft (poplar, willow, …)
- you want to be on the safe side right from the start of a big project!
In our tests, we were able to almost double the load-bearing capacity of the GTS Allstar with just one reinforcement!