When building a treehouse, the primary concern should be safety, with enjoyment a close second. With active kids and pets, a treehouse that is not well located or sturdily constructed can lead to issues. Here are the steps and helpful tips for building a treehouse, with supportive references to help along with this DIY project. As a side note, keep in mind that hiring a professional is always an option and sometimes the best choice for less experienced DIY hobbyists.
Step 1: Choose the Right Tree(s) in the Right Location
The best trees for treehouses are sturdy and strong – for example, ash, maple and oak are great. Some apple or beach types of trees may also work.
Deciduous trees are sometimes preferred since they grow slowly and carry a lot of density in their lower limbs, but sturdy conifers could work as well. You want to pick trees that stay strong throughout the year and can withstand winds and wintry weather.
The branches should ideally split enough to form a cradle, at a comfortable height off the ground – at least 9 feet if possible. Make sure that the tree is completely healthy and has not been infested with anything that hollows out the trunks and branches.
Finally, choose a tree that is in a slightly secluded area. If people constantly walk across the ground next to a tree, this may compact the soil and eventually weaken the tree. In some cases, you may be able to find multiple trees that are close enough to form part of the base. This guide covers a treehouse built on a single tree, but the same principles apply.
Step 2: Plan and Create a Design
Before you get the material, take your measurements and begin construction, you have to plan. You can gain inspiration from some trusted sources, such as David and Jenny Stiles’ guidebooks or Black & Decker’s “Complete Guide to Treehouses".
What are You Building?
Decide what type of treehouse you are building. For example:
- Is it a standard (say 8’ by 8’) room only? Is it square, rectangular or more complex shape? What is the square footage?
- Will there be a deck? What is the square footage?
- At what height will the treehouse be?
- What types of other features do you want – e.g., a crow’s nest, slide, zipline, fire pole or rope swing?
Choose the Safest and Sturdiest Design
Don’t get carried away. Choose to be prudent. For example:
- The height off the ground should never exceed 8-10 feet. It should be at least a couple of feet above your head level, but not so high that serious injury could occur.
- The same goes for installing ziplines or other features which are great fun but could also be dangerous.
You may want to consider padding the ground with mulch or other material that won’t harm the soil around the tree but will provide some cushioning to break a fall.
Step #3 – Get Your Material and Tools
Basic Material Required
The sizes and quantities will vary, but in general, you will need the following:
- Pressure-treated lumber of varying length according to specs
- Pressure-treated decking material
- Galvanized lag screws, washers, joist hangers, and rafter ties
- Other material – such as nails and deck screws
Other accessories, such as a ¼ inch pulley and tarpaulin, can be added as necessary. Choose screws with thicker bores (e.g., ¾ inches) since they will be stronger.
You will need the basic hand tools, such as a hammer or even flooring nailer, saw, square, level, adjustable wrench, and a tape measure, along with some power tools such as a cordless drill and jigsaw. Other finer tools such as a miter saw, router saw, and table saw may help you hone the construction more finely but are not 100% necessary.
A stepladder or full ladder will be needed for you to work safely.
Step #4 – Build the Base Support
The base support is one of the most important steps in the process. The notches should be cut at least 1-1.5 feet above the height of the tallest adult in the household and about a foot below where you expect your treehouse floor to be located. The measurements will depend on the dimensions of what you are building and the positions of the tree branches.
Three other tips here:
- Your boards will need to be cut to fit the dimensions. Measure carefully before you start cutting them since you want the support to fit snugly.
- Cut slots into the trees at the spots where the support is attached to the tree. This will allow for some movement during strong winds and also allow the tree to grow.
- If you build higher up, you may want to use sliding beam support.
Step #5 – Build the Platform
You can build the platform in three steps:
- Lay the platform timber on the ground and cut to the size required.
- Screw the platform woods perpendicularly into the support beams. Ensure the horizontal joists are spaced out so the platform can be fitted around the tree.
- Get the platform up at the proper level, center, and then secure it. Put the end beam and screw down the other end after checking to see that everything is centered correctly.
Step #6 – Attach and Brace the Platform
Use rafter ties to attach the platform to the base nailed to the tree with a nail gun. Attach galvanized nails to attach joist hangers – the platform is now attached to the support.
Bracing will likely be necessary whenever you are attaching the ends of the platform to a single tree. Otherwise, the platform may be unstable. A popular way to brace is by using two 2x4 pieces of lumber meeting at a 45-degree angle and secured by a single lag screw.
Step #7 – Lay the Deck Out
Once the platform is secured (and braced), you can lay down the deck. The main trick here is to carefully cut around the trunks, leaving some space for the trunk to grow and move.
Step #8 – Add an Entryway
Add an entryway into the structure so there isn’t a moment when kids climbing onto or off the platform could be at risk.
One way to accomplish this might be to attach a slightly lower-level platform at an appropriate point – perhaps where the support beams jut forward – so there is a “step” onto the main floor.
Step #9 – Build the Railing, Walls and Roof
The railing and walls can be built out in the normal way. Use vertical posts at the end as uprights for the railing, and then use either new timber frame structures or recycle old fences.
The roof can be created several ways – from a simple tarp stretched over corner posts at one end to a fully built-out timber roof.
One of the issues to consider with the roof is the weight that it places on the whole structure.
Step #10 – Add a Ladder, Pulley, and Other Accessories
Put up a ladder at the entryway. Add a pulley with a ¼” rope, always a kid favorite. If you are adding ziplines or other features, attach them at the right height and angle. While enjoyment is important, safety is vital. Now that your treehouse is ready, you and your family can enjoy it to the fullest.