Every kid wants a tree house but not every tree is the best one for building a safe play area. In this HowTo we will look at some of the problems you will come across when trying to build a simple but safe tree house and some alternatives that can provide fun and safety at the same time.
Tree houses are temporary structures, they aren’t as much pretty or warm but when building one you will have to apply many of the same skills used in building your family’s home. It is better to take a little time planning rather then waiting for an accident to happen and learning by trial and error.
Picking the right Tree
When selecting a tree you will be limited to the ones in your yard and there is a good probability that your stock of trees won’t have that perfect tree. This is not always a problem because you can often use a branch as the main load point and then long 4×4 posts to support the opposite sides from the ground.
The type or species of tree you select is important for stability. Never select a fruit tree like an Apple, Pear or Crab Apple tree because although their branches may get large they are brittle. Additionally a fruit tree will bring pests including bees and your fort is likely to get infested with nests.
Hardwood trees are your best bet. Oak and Poplar trees are a good selection but when they mature the lower branches can be pretty high off the ground.
No matter what the age of the child you should never build so high that it could be dangerous. It only takes a fall of about 10 feet to seriously injure or kill someone even an adult so never build so high that injury is a likelihood.
Inspect the tree for any rotting or bug infestation. Sometimes carpenter ants or termites can get into the core of a branch or trunk and although the tree may still look good it could collapse under the weight of a tree house and a few kids inside it.
In addition to bugs and decay lightning can cause damage to the internal structure of a tree and although it still looks stable it may be an accident waiting to happen. Look for cracks in the bark of the tree where the bark has exposed the inside of the trunk or branch.
NEVER BUILD ON A DEAD BRANCH if the branch does not have leafs growing on it or if it has been pruned poorly it will snap away from the trunk under load.
The Best Branch
It is always best to build as close to the trunk of the tree as you can so when picking branches you want to find ones with a long flat top surface with no obstructions. You don’t want to be trimming large branches to build your fort because you may endup killing the tree.
By building close to the trunk you have a base for your floor and a support for your wall this will help stabilize the whole structure.
The best branch is actually a pair of branches that are on or about the same level. This will allow you to support both ends of the floor.
If you don’t have two branches next to each other you may have a branch that forks. This is a good option if you can still stay close to the trunk and there is no flexing.
You never want the branch you are building on to flex so pick a branch that is at minimum 6 inches in diameter.
Attaching the structure to the Tree
To attach the structure you want to use as few lag bolts as possible. Galvanized Lag bolts are best because they will not rust. An even better option is to build around the branch by using caridge bolts with threads, nuts and a lock washer. This will allow you to clamp securely to the branch or trunk without actually penetrating it.
To the right you see a picture of a poorly designed floor structure. Although they are making good use of both the main trunk and a secondary branch you can see that the lower supports do not provide enough strength for the floor system. This is dangerous.
Using nails to attach to the tree branch or trunk is pretty useless because the tree is still alive. The nails may hold for a short period of time but they will eventually loosen and could cause the branch or tree to die.
Strapping is another option however it will require special tools. Steel bands can be used to secure wood pieces but remember to use some scrap wood to protect the bark.
Considerations for smaller Children
If you have small children under 14 you should really consider building a play house or buying a stilt house kit that will give some of the same feeling of a tree house but won’t be filled with any of the dangers.
Kits can be purchased online or you can get a set of reviewed plans and assemble the house yourself.
I strongly recommend this option for any children under the age of 10 but you may also want to look into ground level play houses or even a shed for larger kids to hang out in.
Getting Materials
If you are lucky enough to have a few homes being built in your area you can probably pickup some scrap lumber from their trash dumpsters. You should always ask before taking anything and never take any wood that is not inside the dumpster… Even if it is laying against or near the dumpster the contractors may have placed it there for a reason other then for throwing it way.
Dumpster diving for lumber can save you money but also it is a great way to stop construction materials from going to waste and filling landfills.
Most contractors will be fine with you taking scraps but remember don’t get injured by boards with nails and don’t use lumber that has a lot of damage.
Most of all don’t let your kids go alone because they are likely to get into trouble due to work site safety problems and kids being kids.
The YouRepair Store sells a full line of building products including plans for tree houses and play houses.