Stringer stairs to deck

I'm building some steps up to a deck and looked up how to do the calcs for the stringers. There are so many variations my head spins. I want to clear up a few things. I gather you just work out how many runs (treads) and rises to get to the deck height and this gives you the baseline measure of how far they will extend. See my illustration. Then is the length of the stringer simply the hypotenuse calculation using the height and baseline (span/total run)? And is this measure the centre line of the stringer? If the last footfall is on grass or paving is that included in the calcs (as the last rise and standard run) to get a stringer length?

I've seen various templates on how to lay out the steps on the stringer and wonder how they guarantee the steps will be level.

Some stringers have a sort of lip over the deck. Is this to hold it in place while you fix it or is there another reason?

Thanks

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A simple calculation for an easygoing staircase is 2R + T = between 585 and 625
An ideal rise (R) is 170 to 190mm and your corresponding tread(T) can be a figure that lands within the above formula
You can under cut / overlap the nosing to the back of the tread below by 20mm to reduce your go and make stair more comfortable

The easiest way if you don’t want to use a builders square or trigonometry is to first establish your tread and rise height
Make sure you are using the rise measurement from the finished ground level where the stair ends which will not necessarily be the same as directly below your deck
Once you have that worked out get a spare sheet of ply or some rigid cardboard etc and place it where your stringer will go and then starting at the top start physically marking in each tread and riser using a small level and pencil. From that you can transfer the set out onto your stringer
This is not the quickest way but it will be less confusing as you can visualise what is going on

I always refer to Stair Calculator | Detailed Plan Diagrams
it is free, easy to understand, it has pictures.

it is a good starting point as it gives you the names of what may be technical which you can google further if needed.
cheers

Hi
I teach stair making at a TAFE in Victoria and your questions and 'head spinning' is quite normal, if you have not done this before, so do not beat yourself up.
I will try and answer you questions to the best off my ability, however this I would normally do face to face.
First of all these are external stairs and need to be treat some what different to internal, but I will get to that later.

First measure your height at the deck that's your 'Rise' then divide this by say 175 to start with and see if that calculates evenly. You most probably will have to up or down to get this to work. Remember the higher the number the greater the rise (the distance between treads). When you are happy with you 'rise' now calculate your tread 'Going' (the depth of the tread) 240mm is the minimum. Therefor the number of risers x treads (depth) will give you your total 'going'. Just as you have drawn above.
Remember that when you have worked out your total 'going' and if the ground is sloping, your actual rise you calculate at the deck could be could be wrong and you will need to adjust your rise to suit. I hope you understand what I mean here.
Just remember the higher the rise, the steeper the stairs, the lower the rise the easier it is to walk up and down but you will need to increase the going (tread) depth.

You state 'Some stringers have a sort of lip over the deck.' That's call a 'Hook' and really is not necessary and is really up to you, but it does help when you are installing.
Setting out the stringers is the tricky bit here if you have never done it. This can either be done using a builders square or by making a 'stair makers boat' to set out. I think I will post this bit later as I think a picture will speak a thousand words.
Assuming you have put the stair together, you will need at least two threaded rods and bolts that will go through the stringers and under the top and bottom treads to hold it together, regardless if you have used batten screws to fix the treads. As the stairs are exposed to the elements the treaded rod holds everything together.
If you want to post the actual Rise, I can post a set out if you need it.

Regards

Kevin

Thanks Kevin, lots of really good info here. The first issue is always working out the nomenclature so I stick with goings.

My measurements are as per the illustration, just double-checked. The ground is flat. The total rise to the deck surface is 0.875 and with a rise of 175 per step, so that gives me 5. Four timber steps then the ground is the last footfall.

I'm using 240 treads so the total going is 1200.

Thanks Beardy, I did this sort of thing when I created box stairs trying to sort out all the fiddly bits using offcuts on plywood to lay it all out, so creating a template like this is a good fallback if all else fails. And yes as Kevin also points out, I didn't think to measure at the end point of the stair run, which could easily catch a novice out.

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Originally Posted by Beardy

The easiest way if you don’t want to use a builders square or trigonometry is to first establish your tread and rise height
Make sure you are using the rise measurement from the finished ground level where the stair ends which will not necessarily be the same as directly below your deck
Once you have that worked out get a spare sheet of ply or some rigid cardboard etc and place it where your stringer will go and then starting at the top start physically marking in each tread and riser using a small level and pencil. From that you can transfer the set out onto your stringer
This is not the quickest way but it will be less confusing as you can visualise what is going on

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