The staircase is one of the most important parts of the treehouse. It’s the first thing anybody will touch and walk upon, and hence will set the mood for the whole treehouse experience! It should be solid, sexy and sturdy; enticing people to walk up and go into the treehouse.
If you’re not up to date with the treehouse design series, head back and catch up on parts 1 & 2 about picking a tree and building a basic platform. In this post we’re going to look at what goes into constructing a strong and long-lasting staircase.
The Components & Materials…
For a low treehouse, say only 3-4 meters from the ground, it’s possible to rest your staircase directly between the ground and treehouse, with no additional support to the middle (as shown above). If the gap gets much bigger however, then you may have to think about a diagonal or vertical support piece to prop up the staircase at the middle to stop any flex when people walk up.
The first step is to select your two main posts. This could be thick round wood pieces – at least 20cm diameter – or flat slab / plank type pieces (like shown in the above). You might be thinking that round wood pieces will be much stronger, but as the cross section width is what matters here, the flat slab pieces when orientated upright like shown will be just as strong if not stronger.
The Step thickness depends on the width of your staircase. As a rough guide a staircase 80cm-1m wide should have steps at least 1 inch thick. Any less and the steps may flex under the weight of a person.
Be sure to use durable & resistant wood! In the heat and humidity of the tropical south Indian climate we usually use a timber such as Eucalyptus or Acacia for our stairs, and treat the wood with Varnish to make it water proof.
Calculating the amount of stairs and the step dimensions…
Three factors are key to determine how many stairs you will need:
- Step height i.e. the vertical distance from one step to the next.
- Stepping Width. i.e. the visible portion of the step you have to stand on.
- The vertical and Horizontal height of your staircase
A typical step height is 20cm. Of course you can have your step height as much as 30cm, but it just starts to get more difficult to walk up and down. Likewise comfortable stepping width really should be no less than 20cm, basically enough for the average person to get their whole foot onto one step.
Different types of staircases may require you to have a larger step height or width; especially, for example, if the staircase is really steep then you need to cover more vertical distance requiring the staircase to have a larger step height.
Now you need to figure out what distance your stairs are covering vertically and horizontally. Firstly Measure the vertical distance from the top point of your staircase with a tape measure. Now use a plumb bob (small weight suspended from a string) to get the point directly below the top of your stairs and mark this point on the ground. From this point you can now measure horizontally to the base of your giving you your vertical and horizontal distance as two sides of a right angle triangle. See the images for the next paragraph:
We can now calculate the number of steps. Let’s assume step height and width are fixed at 20cm and the distance we need to cover is 2m vertically and 2m horizontally. Dividing the vertical height by the step height (200cm / 20cm) gives us exactly ten steps. Likewise, horizontally, at increments of 20cm per step, ten steps are needed to cover the 2m horizontal distance, this is displayed in the diagram below.
Let’s consider for a second that the vertical distance is actually 3m, not 2m. We can either increase the step height to 30cm (300cm/10 steps = 30cm step height) or if we want to keep the step height at 20cm then we can increase the number of steps to 15 (300 / 20cm = 15 steps) see both diagrams below. However, you would now be covering 200cm horizontally with 15 steps, (200cm / 15 steps = 13.33cm step width) giving us a much smaller and frankly dangerous stepping width.
Making a comfortable staircase is about finding the best compromise between these factors so that it’s safe, and easy to climb.
Construction & Assembly
Assembling your staircase can be done in two ways. Either the main beams get fixed from ground to treehouse – after which the steps are cut and inlaid directly into the beams – or you can assemble the staircase on the ground and then pull it up for fixing afterwards. Each method has its own benefits so I’ll try to touch upon both.
First you need to mark the level and position of your steps. If the posts are fixed you can do this with a spirit level and pencil like shown below. From your first level line you measure up the distance of your step height, 20cm or whatever it is, and mark the line for the next step. To copy the marking onto your other post, use a straight edge (or straight-ish piece of wood) to copy the level of your marking and make the line again with level and pencil. If you’re assembling on the ground you must work out your angle manually before hand and mark it onto both sides of your beams.
When your markings are made place a step onto the line and trace around it to get the marking for your groove. Repeat for all your steps and cut in with a circular saw – 2cm deep should be more than enough for 1-inch think planks. Carve out the rest with a chisel and start fitting the steps into the grooves. To get a really tight fit its good to taper the ends of your steps like in the image below so that they have to be compressed in by hitting with a mallet or nicely pulled in with screws.
Style & Deco
Once your steps are ready its time to fix on some upright pieces for the hand and safety rails. The handrails can be done in a variety of different ways, but it’s really nice to use one long piece for running your hand along, polished and finished nicely. The strips underneath should be spaced at 30cm max, to provide a barrier to stop somebody falling out the sides in case they slip on the stairs; make 3 – 4 rows of rails underneath the hand rail for this. Here you can get creative with the design, cross the strips over each other, cut them into wavy shapes or use full branch pieces that give a gnarly natural look to your stairs.
I hope this post gave you some ideas – send us some photos of a sexy staircase!