How to build a treehouse

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If you build a treehouse in your garden, you can teach your children to love nature at the same time. Of course you’ll build your treehouse in a tree, with a floor that also serves as a support frame. The treehouse has an open deck, reached by fixed stairs, a fixed ladder or a rope ladder.

Safety
Ensure that your treehouse is solidly structured. Take your time for it. The exact way to build it will depend on the situation in your own garden, but you can follow these step by step instructions as a guide. You can choose your materials from different kinds of wood.

Required materials
Planks, wooden beams, roofing tiles or corrugated sheet.

  1. Selecting a tree

    Choose a tree with the right structure, and make sure the tree you select is healthy – this is essential to give your treehouse a solid, strong structure. Suitable kinds of tree for a treehouse include beech, oak, maple and large firs. A tree with a strong, robust trunk, heavy branches and deep, firmly anchored roots makes a good base for your treehouse. The tree shouldn’t have any signs of disease or parasites that could weaken the treehouse. If you’re not sure whether your tree is suitable, it’s a good idea to consult an expert. He (or she) knows all about tree preservation and how to treat diseases and parasites, and can help you to choose the right tree before you start to build your treehouse!

  2. Check if you need permission

    Before you start, check if you need permission to build a treehouse. If necessary contact your municipal council, and check if there are any local regulations, by-laws or other matters that could affect your treehouse, such as height restrictions. You sometimes need to apply for a permit before you can build a treehouse. There may also be restrictions if you have protected trees in your garden.

    It’s also a good idea to first contact your neighbours; this will prevent later complaints and will help to maintain friendly relations. The treehouse could spoil the view from their homes, or it could overlook their rooms and disturb their privacy. You should also contact your insurance company, to make sure the treehouse is covered by your property insurance. If that isn’t the case, then any kind of loss or damage caused by the treehouse will not be insured.

  3. Choose the right position

    After you’ve selected the most suitable tree, you can decide what kind of treehouse you want to build. For a standard 3x3 metre treehouse, choose a tree with a trunk of at least 30 cm diameter. You can calculate the diameter by measuring all round the trunk with a tape measure at the place where you want to build your treehouse. Then divide the measured result by π (3.14) to give the diameter. It’s also important to first check how the base of the treehouse will be positioned in the tree. Measure carefully where you need to make cut-outs in the trunk and branches. Leave plenty of free space around the trunk of the tree. The thickness of the supporting beams will depend on the specific situation and the size of the platform.

  4. Supporting the treehouse

    There are a number of ways you can support your treehouse. Whichever method you choose, remember that the tree will move from side to side with the wind. So make sure the treehouse won’t be damaged by this movement. You can choose from different ways to support the treehouse:

    1) Screwed to the tree
    This means the supporting beams of the platform are screwed in place directly to the tree trunk. This is the commonest way to support the platform. But this method is also the most likely to damage the tree, although you can minimise the risk by using the right materials.

    2) The ‘floating’ method
    In this method, the treehouse is suspended from strong, high branches using rope, cables or chains. However this method doesn’t work with all kinds of trees, and isn’t intended to support a heavy treehouse. For example it’s ideal for a platform only, with no heavy enclosure.

    3) Using supporting poles
    The supporting poles are dug into the ground close to the tree, and they aren’t fixed to the tree itself. You should leave plenty of space around the platform, so the tree can move freely in the wind. This method is least likely to harm the tree.

  5. Access to the treehouse

    Before you start to build your treehouse, you first need to decide how you’ll be able to climb up into it. Keep your children’s safety in mind! The way you reach the treehouse must be sturdy and safe. There are a number of ways to do this:

    1) Rope ladder
    You can make this kind of ladder out of rope and a number of short rungs which are fastened to the rope, one under the other, right down to the ground. You have to get used to using a rope ladder, and it my feel a bit ‘wobbly’ when you’re climbing up it.

    2) A fixed ladder
    This is a standard ladder which you can buy anywhere. It provides a quick and easy way to climb up to your treehouse.

    3) Fixed stairs
    Fixed stairs are the safest way to reach your treehouse. If you decide to use fixed stairs, it’s a good idea to add a banister rail or handrail at the side of the stairs for extra safety.

  6. Obstacles

    Should you build your treehouse around branches that are in the way, or is it best to remove them? Obstacles can influence the design of your treehouse. It can often be a challenge to modify the design to allow for the irregular shape of the tree. But when it’s finished, you’ll be able to look back on your work with satisfaction!

  7. Safety first

    Before you start building your treehouse, remember that the risk of falling is the biggest danger. You can take the following measures to reduce this risk:

    1) Don’t make your treehouse too high
    Building your treehouse too high can be dangerous if will be used by children. So don’t make the platform higher than 1.5 to 2.5 metres.

    2) Build a safety fence or rail around the platform
    A safety fence or rail around the platform will help to prevent children from falling off. A safety fence or rail around the platform should be 70 to 90 cm high, with a spacing between the vertical posts of not more than 10 to 15 cm.

    3) Lay a soft ground surface
    You can lay soft, natural materials like wood chippings in the area under the treehouse. This won’t in itself prevent falls, but it does ensure a soft landing!

  8. Fixing points

    A tree with V-shaped branches provides extra strong support for the treehouse, and it means you have 4 fixing points instead of only 2. Drill holes at the 4 fixing points on opposing branches. Use a 10 mm drill and make sure the holes are horizontal and at the same height (A). If the fixing holes are not well aligned, it could mean the platform won’t be level.

  9. Supporting beams

    Measure the distance between the fixing holes on both sides of the branches of the tree, and mark out this distance (A) on the 2 supporting beams. Make sure this distance is the same on both the left and right sides of the supporting beams. Starting from this reference point, draw a 5 cm line to the left and right (total length 10 cm), and mark the ends of this line. Do the same at the other end of the beam. Drill two 12 mm holes on both sides of the marked ends of the lines you drew. Then, use the jigsaw to saw out a 12 mm wide slot between the 2 drilled holes. This is necessary to allow the tree to move freely in the wind without splitting of the tree trunk or damaging the platform.

  10. Supporting beams (continued)

    Fix the 2 supporting beams to the tree at the marked height, using 4 coach screws (hex‑head wood screws) of size 12 mm and length 200 mm. Fit washers between the screws and the supporting beam. Repeat this on the other supporting beam on the opposite side of the tree trunk. Make sure both supporting beams are at the same height and parallel to each other. By pre-drilling the fixing holes you avoid splitting of the tree trunk and branches, and of the supporting beams. If your treehouse has a relatively high total weight, you could consider using thicker and stronger supporting beams.

  11. Cross-beams

    Fit 4 cross-beams of 50x150 mm, equally spaced and parallel to each other. Fix these cross-beams with 80 mm long chipboard screws. Then fix 2 beams of 50x150 mm to the ends of the 4 cross-beams using 80 mm long chipboard screws.

    Note: the platform must be at right-angles to the 2 supporting beams, as otherwise the floor planks won’t be straight when you fit them later.

  12. Beam supporting brackets

    Fix the platform to the cross-beams with 8 beam supporting brackets. Make sure the whole structure is perfectly level and all the corners between the beams are at right‑angles to each other. Fit 4 beam supporting brackets to the 2 sides of the platform.

  13. Supporting beams under the platform

    The platform is still a bit unstable, but we’re going to secure it with 2 supporting beams of 30x100 mm. These beams are fixed with 2 brackets to the top side of the platform. Fix the underside of the supporting beams to the branches of the tree.

    Saw the top sides of the supporting beams to size at an angle of about 45°, depending on your own situation. Fix the supporting beams to the inside of the platform, again using 2 beam supporting brackets. Fix the 2 overlapping supporting beams together at the bottom with a 100 mm long M8 bolt or threaded rod. Use washers between the supporting beams and the bolts.

  14. Fit the floor planks of the treehouse

    Check where you need to saw cut-outs in the floor planks so they fit neatly around the tree trunk and branches. Allow a spacing of about 10 mm between the planks. If necessary, use the jigsaw to make round openings where the tree trunk and branches have to pass through the floor. Fix the ends of the floor planks using at least 2 screws. Use a step ladder or ladder for this job, and finish the floor neatly so it is free of splinters.

  15. Surrounding fence

    Fit 80 cm high uprights at each corner of the platform for the surrounding fence. Make the corners of the fence using 2 lengths of wood of 60x10 mm. You can use thicker wood if you want, but remember that the total weight is also important for stability. Fix these lengths of wood in place with screws through the sides. Fix the banister rails, made of lengths of wood of 60x10 mm, on top of these vertical uprights. Saw the banister rails neatly to size at an angle of 45° (see the inset circle in the drawing for a detail view). Then screw the banister rail in place on top of the uprights, followed by the vertical posts with a spacing between them of about 10 cm. Screw all these posts in place with countersunk chipboard screws. Safety is priority No. 1, especially with (small) children!

  16. Fixed stairs

    Build sturdy, reliable stairs fixed to the side of the platform. The safe angle of the stairs for a platform with a height of 2.5 metres is with the bottom of the stairs about 1.35 to 1.80 metres in front of the top. Make the stairs with uprights of 50x10 mm and steps of 50x12 mm. You need to choose the width and length of the stairs to match your own situation. Fit the steps to the uprights with an equal spacing, and mark where each step will be fixed. You can screw blocks to the uprights, so you can then screw the steps on top of these blocks. Or you can make grooves in the uprights with a depth of 25 or 30 mm, and then you push the steps into these grooves. Saw the uprights and steps to the right length, and fix them in place with glue and screws.

  17. A hut with 3 walls

    You can build your wooden treehouse in various designs, for example with 3 walls and a roof made of corrugated sheet. But you can also simply make a roof out of sturdy plastic sheet supported by wooden beams, or you can fix a small camping tent on the platform.

  18. The A-frame

    We’re making a treehouse based on an A-frame with a slope of 60°. You can make this treehouse using the same uprights that you used earlier. You’ll need to adjust the height and width to match your own situation. If one of the branches needs to pass through the roof, you’ll need to fit an extra beam with a cross-beam.

  19. Make the roof watertight

    To make the roof of your treehouse 100% watertight, staple thick plastic foil to the A‑frame before you fix the roofing tiles or planks in place.

  20. Finishing your treehouse

    Screw the first roof planks in place at the top of the A-frame and then push the other planks under them. Screw the roof planks in place in an overlapping pattern. Saw the front and back walls to size, with windows if required, and screw them in place to the A‑frame. Pre-drill the screw holes and use countersunk screws for a smooth result.

  21. Tip

    If you want to make your treehouse weather-resistant, of if you just want it to look more attractive, then you could consider not just using varnish but also giving it a coat of tung oil (Chinese wood oil). This is non-toxic and protects the wood. It is used by professionals, and it is one of the best natural finishes available. You could also consider painting your treehouse in the same colour combination as your house!

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