Estimate the platform timber, decking boards, railings, roof and fixings for a raised treehouse or play platform.
You get the platform joists, the linear metres of decking boards, four corner support posts, the railing and an approximate baluster count, plus roof sheathing if you add a roof. Treehouses must be built to carry the weight of children safely — use treated structural timber, strong fixings, and support the platform on posts rather than relying only on the tree.
For safety and to protect the tree, most modern designs support the platform on its own posts or a combination of posts and a small number of tree fixings, rather than bolting everything to the trunk.
For a child play platform, railings of around 0.9–1.0 m with narrow gaps (about 100 mm) help prevent falls. Adjust to suit the height of the platform.
Use pressure-treated structural timber for joists and posts, and decking-grade boards for the floor, all fixed with corrosion-resistant screws and bolts.
Use a few large treehouse attachment bolts rather than many screws, and leave gaps so the tree can move and grow. Never wrap straps tightly around the trunk.
For family use 1.5–2.5 m off the ground is common; lower is safer for young children. Always add sturdy railings, which this estimator includes.
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OpenComplete decking material list — joists, deck boards, posts, fixings and concrete — from the deck dimensions.
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