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How to calculate this stringer layout?

15K views 89 replies 18 participants last post by  TG Deck  
#1 ·
Ok let me see if I can explain this. I want a flush landing at bottom of stairs not the top. I'm using build clac

Rough rise 86-1/4"
Rough run 92-1/8"

The rough rise is from top of joist on lower deck as you can see in picture. But what should I be putting in for rough rise if I want a flush landing at the bottom deck. So basically I want my last tread on bottom tread to be flush with lower deck tread.

Is it as simple as selecting flush landing but drop the stringer down to Crete the flush landing at the bottom.

 
#2 ·
#3 ·
You need to figure out what the rise for each step is to have it land on the top of the deck. Then you need to add that rise your rough rise number.

That will then put the bottom of the stringer that far below the level of the other deck. Leave the run the same and by adding one more rise it shrinks the run of each step.

There lies the problem though. You end up with a rise and run that are almost equal. Code is a 7 3/4" rise max and 10" run minimum. You can't get that with your numbers and dropping to a flush landing at the bottom. That makes it even steeper.
 
#4 ·
I can put stringers on top of current deck but cosmetically it would look better flush at bottom.

So if I measure down from rough rise on top of joist the amount my riser is at that point then mark that on the rim joist then I will have roughly 7.5" more rough rise and that will give me a flush landing rough rise.

I'm confusing my self now. Might be a sketch up time
 
#7 ·
So, your saying that the deck should have actually extended towards the steps another 10"? Basically, you are just using algebra here. Not sure how that works on your calculator, but you are trying to find what is essentially "unknown" at this point.

If you take your total rise from top of deck to top of landing and add 8", this will give you an approximate total rise. You can then divide that total by 8 to give you the total number of risers. In your case, you will have the exact amount of actual treads and risers, instead of the usual, "one more riser than tread.

I think I just confused the whole thread now.
 
#8 ·
Barri, plug in your rough rise and run. Then input 10" for desired tread width, then go back and put 0" for the rough run.

Doing that calculates the run of the stairs based on the desired rise and desired run. Your desired rise and run need to be 7 3/4" and 10". Those are the most extreme numbers they can be and meet code.

For your deck, the issue is they are too close together and the height difference is too much to do anything other than land on the deck. It will tell you a run of 110" with a rise of 7 3/16".
 
#18 ·
For layout, Barri, think of the platform as a single step. When you're using BuildCalc for the layout it's really easy to tweak all the numbers and it does the calcs for you.

So if you want a set of stairs with a 4' landing in the middle, once you have the rise and run figured out as if the landing wasn't there, then add 4' to the run. Use a rotary laser to check the elevation at the end of the run.

The ground is never level so if you add 4' it will change elevation and you will need to adjust numbers. The idea is to find where it lands, then measure the total height, and it gives you numbers to play with in the app.

That will help you know where to pour concrete for stringers to land on if that's what you do. If you want to use the app for layout of the stringer, you have to then change the rise to what it needs to whatever it is to the bottom of the upper stringer and same for the lower for the layout diagram and measurements to be right.

Hopefully that makes sense...