Introduction: Wildlife Observation Tower
During normal everyday life this tower is perfect for enjoying wildlife as it allows us to look down and over the terrain rather than just across the horizontal, where animals would be missed, hidden in the ground cover. Additionally, in the darker recesses of my consciousness, this tower would provide excellent early warning against attack by marauding herds of flesh eating zombies during the impending zombie apocalypse!
The main considerations in the design are firstly safety - the tower must be secure and there must be an adequate railing in place at the top. Secondly, it must be easy and cheap to build. The third consideration is that it is to be built on uneven ground, which poses a particular design challenge.
Essentially, it is constructed in a similar way to a scaffolding tower used on building sites and, importantly, access is through the centre of the tower rather than on one of the sides. Going up a ladder in the centre is a lot safer and puts less strain on the tower itself.
The deign has been created in the wonderful Autodesk 360 software which is available for free to hobbyists - THANKYOU AUTODESK! This has allowed me to look at each step very carefully and play about with parts of the structure until it is absolutely perfect. It's not a complicated design by any means, but it would be really great to take this set of plans and the necessary tools and materials into the marsh and build the structure in no more than one day.
The marsh seen in the photo above is home to a vast amount of wildlife including woodcock, buzzards, foxes, ducks, herons, frogs, etc. Can you spot the two foxes nestled in the undergrowth?
Step 1: Animation of the Build
Step 2: Parts and Tools
- Timber 4" x 4" x 20m
- Timber 5” Decking x 35m
- Timber 4” x 1” x 80m
- Timber 3” x 3” x 750mm x 8 stakes
- Timber 2” x 1” x 20m battens
- 3m Scaffolding planks x 8 of
- 1m x 8m heavy stock fencing
- U nails for fastening the above
- 60mm x no.5 x 400 screws
- Decking screws
Coach bolts 12mm x 100mm and washers x 8 of
- Support cables, tensioners, anchors and fittings
- Metal post holders for above x 4 of (See photo above)
- Hand saw
- Cordless drills and screwdriver bits
- Sledge hammer
- Spanners/socket set for coach bolts and metal post holders
- Fencing cutting tool
- 1m Long spirit level
- Tape measure
Step 3: Fix in the Metal Post Holders
The post holders are knocked into the ground at approximately 2m square. The measurement is not critical at this stage and the holders will tend to go off the mark due to stones and rocks in the ground. They will also tend to go off vertical as well, but as long as this is not extreme, it will not affect the construction.
Step 4: Bracing the Uprights
Pegs are knocked into the ground at roughly 1.5m distance from the uprights and 2” x 1” battens are cut to 2m long and used to keep the uprights in position with screws. The uprights need to be exactly vertical by adjusting the batten positions if necessary.
Step 5: Assemble the First Level
The first level is created with 4” x 1” timbers at approximately 1m above ground level. Each side needs to be measured independently as, most likely, they will not be 2m. The most important point here is to get the timbers horizontal.
Step 6: Assemble the Second Level
Scaffolding planks are laid out on the first level, allowing easy and safe access to the second level, which is screwed in at 1m above the first level.
Step 7: Assemble the Fourth Level
It’s really important to miss out the third level and go straight to the top railing. This allows the floor level to be positioned at exactly 1m below the railing, which is critical for building regulations. Check your local building regulations for hand rail heights!
Notice that one of the uprights is too high and protrudes above the hand rail – this is because the ground is uneven and this will be trimmed off later. The hand rail is built to the height of the lowest upright which will sit on the lowest bit of ground.
Step 8: Assemble the Third Level, the Floor
Now build the floor level.
Step 9: Build in the Diagonal Cross Braces
The diagonals are screwed in and then trimmed off with a hand saw.
Step 10: More Diagonals
The diagonals are always inserted on the inside of the uprights, with the horizontal timbers fastened on the outside.
Step 11: Finish the Diagonals
All the diagonals are in place now. These will provide important bracing for the structure which would be unstable without them. Each set of diagonals and respective horizontal timber now form a star shape. Insert a 12mm coach bolt at each point where all 3 timbers cross, which should be somewhere close to the middle of the star. If the 3 timbers do not all coincide at one point, use extra coach bolts to fasten them together.
Step 12: Construct Floor Support Struts
The struts shown above are required for fastening down the floor boards. Also, we need to allow for an access hatch so that we can climb through the floor off the ladder. Do not miss out the diagonal braces as these are essential! The internal dimensions of the hatch need to be as small as possible, 800mm square should be ok for most people to get through. Check you can actually get through the hatch before building the floor!
Step 13: Build the Floor and the Hatch
The floor is made from standard decking timbers and is laid down with expansion/drainage gaps between the boards of approximately ½”. The hatch is not hinged, but could be made so if required. The hinges should be recessed to avoid creating a trip hazard.
Step 14: Insert the Ladder and Stock Fencing
The ladder is bolted or screwed into position and the stock fencing is attached using U shaped nails. The fencing needs to be sufficiently robust and should have holes no bigger than the size of a small child, so that they don’t fall through and off the side. Additional railing supports can be inserted if necessary.
Step 15: Support Cables
The bottom bracing is now removed and supporting cables put in place with suitable mechanical tensioners to provide the necessary adjustment. The cables are attached with strong galvanised fittings screwed securely onto the wooden uprights at about 2.5m high and attached to steel anchors in the ground at the other end.
Don’t forget to tighten up the bolts on the metal post holders.
Step 16: Final Step
One section of the first floor horizontals can now be removed to provide easy access to the inside of the tower and the tops of the vertical timbers are trimmed off where necessary. The tower is now complete!