Find 10 mistakes in this plan :-D Answers in the end.

Many beams started cracking immediately, should have gotten lower-humidity wood.

Cutting square mortises was a waste of time, should have used round bars.

Cutting these boards from the beams was a bad idea, should have used 3cm floor boards with no gaps.

Cutting these drip edges wasn't worth it, they don't seem to do much.

Cutting shims for the imperfectly height-balanced anchors

This structure might not satisfy the safety standards / laws / regulations in your region, if you decide to build something similar please do so at your own risk, I assume no responsibility for that.

1100 EUR total price including 300 EUR for 44m of beams. Using cheaper parts can get the price down to 650 EUR:

Price in EUR Comment Cheap alternative
300 Wood 300
50 Black plywood 10
45 Paint + impregnation 30
10 Waterproof wood glue 10
7 Brush 5
5 Sand (50kg) 5
63 Ground anchors (8) 40
31 Lag screws (100) 31
15 Insert screw nuts (100) 0
104 Nice swing hooks (4) 15
10 Handles (2) 6
6 Chain connectors (2) 0
18 Hammock hooks (2) 5
27 Hammock 23
41 Monocular 5
175 Slide 110
80 Adult swing seat 15
30 Baby swing seat 15
47 Bouldering holds 26
20 Stainless 40mm pipe 0
1084 651

Main dimensions:

  • 94mm square beams

  • 215cm height + 5cm ground gap

  • Ladder

    • 242.3cm ladder leg length
    • 60cm gap between the legs
    • 60 degree ladder angle
    • 109cm ladder cross-member short side length
    • 54cm distance to the first bar center
    • 35cm bar distance on centers
    • 4 bars
  • 250cm swing area width

  • Tower

    • Inner area 60cm by 70cm
    • 144cm platform height
    • 94mm gap between the sandbox seat and the bottom beam
  • 90cm distance to the fence / trees

  • 110cm distance to the concrete tiles

Minimum set of tools: screwdriver, wrench for lag bolts, handsaw, chisels, mallet, sandpaper, forstner drill bits, clamps, square, length and angle measuring tools.

Nice to have: 12 inch miter saw, garage vacuum, random orbital sander, laser level, table saw, 18v / impact cordless screwdriver, router.

Mistakes in the original plan:

  • Calculated using 100mm wood size while in fact planed wood has 94mm dimensions
  • Tower deck too high, not satisfying the 70cm minimum recommended railing height. Moved down later.
  • Forgot to account for the offset due to ground anchors height not factored in, important for the slide
  • Ladder allows kids to get too high up. 150cm if the recommended max standing height for a playgrounds on grass. Removed the top bar.
  • Ladder back bottom beam is unnecessary and poses a hazard for falling kids. Removed.
  • Cutting drip edges at the bottom of each beam might have been unnecessary.
  • 11 month old kid can't even walk yet but she crawl up the slide if barefoot! Had to add vertical safety bars in the tower.
  • Using a single beam spanning the entire structure would eliminate a lot of problems e.g. squeaking when an adult swings and tower-ladder alignment
  • Glued in the steel bar using epoxy on both sides, now the structure can't be easily disassembled
  • Sandbox needs a lid to protect against the cat litter and baby crawling in and eating sand :) Wooden lid I made flexes up due to moisture and becomes a finger hazard. Need to make a plastic lid with no gaps.
  • Ladder bars should be round e.g. 40-45mm diameter. Square bars are hard to install, painful to use barefoot and are less safe on impact.
  • Swinging board in the ladder was a bad idea, also prevents hammock installation
  • Plastic slides are flimsy, building a slide myself would be better (and save 2 weeks delivery waiting time). Can't even use it myself due to the 70kg limit.

Mistakes in the execution:

  • Didn't use strings to line up the pieces perfectly, tower is a bit at an angle to the main beam
  • Waited until the last moment to cut the top beam, caused delay due to 2 days required for painting
  • Didn't get the right saw for the beams, imperfect cuts don't allow lag screws to hold things super tight
  • Used too much wood glue on the end grain, looks ugly and gets white after the rain. Not sure if epoxy can be used instead as it might not be flexible enough to follow the wood as it expands and contracts.

What went well:

  • Just 2 weeks from start to finish, can be done in 1 week with better planning and execution. If we ordered a playground kit, it would have just arrived
  • Triangular side of the playground is stable as a rock. It's also a free-play zone where e.g. hand-stand competition or parkour style climbing can be practiced
  • There's a round-trip across the entire playground for the older kids: up the ladder, across the main beam on the belly, down the slide, swings, repeat
  • Playground takes little space visually due to lack of walls
  • Playground allows you to stand high and see far away while only being 2.20m high itself
  • Natural wood color is very pleasing compared to the factory impregnated wood
  • A basic monocular on the tower allows my daughter to see the horses 1km away in the field
  • Distance between the ladder left beam and the tower left beam is 3.2m which fits most hammocks.
  • Hammock can be used as a chair
  • A swimming pool can be placed under the slide
  • Lag screws worked great, will see how they hold over the years

3 weeks after the initial construction, the playground is used multiple times per day by up to 3 kids at a time. Super happy with it!