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Hi. My friend asked me to help him build a timber outdoor staircase with a height of 2.7m.
I've read the regulations (AS1657) and choose the following:
riser = 225mm
going = 240mm
I've mocked up the stringer and if I use 240 x 45 treated pine, I will have around 75mm of timber left after I cut the riser and going.
Is 75mm enough to support the weight? thanks!
Hi @archerwinmakes,
75mm does not seem enough to me. I can't imagine that would support my body weight, let alone include the entire weight of a staircase or multiple people using it simultaneously. I've looked at various designs, and in many instances, the amount of timber left to support the staircase is equivalent to the rise. Have a look at the rendering I've put together below. You'll see how the red rectangle formed by the rise and fall is able to fit in the remaining timber. Unless you're going to have posts incorporated into this design, I don't feel the 75mm you've left will be sufficient. Your design seems more similar to an internal staircase with structural timber beneath it to provide support. I've also included another option where you could rebate the stair treads into the stringer, similar to our treated Pine staircases.
By my rough approximation, the timber you leave should be closer to 180mm.
Please let me know if you have any questions.
Mitchell
If I rebate it, how deep should the rebate be?
Also, if I rebate would the 240x45 stringer be strong enough?
This will have have support. like this:
A rebate of around 8-10mm should be sufficient @archerwinmakes. 290 x 45mm would likely be a more substantial-sized stringer. You'd also need to use threaded rod to pull the two stringers together.
If you were to go with your original plan, would you have the middle brace as per the image?
Mitchell
I see that my friend @MitchellMc has shown you the Wilmaplex Stringer sets. Since the stair set you are building is under one meter in width, two stringers should be enough. However, I suggest checking the rules and regulations of your local council regarding attaching and building outdoor stairs.
At your proposed height of 2.7 meters the length or distance of the ladder will almost be at 4 meters. I've placed a screen shot of the Wilmaplex stairs calculator. It gives you approximations of how long the stairs will be based on height of the floor. This of course does not include the height of the concrete footing. At that length it will probably be necessary to add supporting posts to prevent the stairs from bouncing.
If you need further assistance, please let us know.
Eric
Great, thanks for letting us know @archerwinmakes.
I'm sure our members would love to see them installed if you could please share some photos with us.
Feel free to also let us know if you need a hand with anything else. We're here to help.
Jason
