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FISH96 06-08-2008 10:34 AM

Laying Out Stair Stringers

hope you all are enjoying the weekend.

i have read all i can get my hands on concerning the above. i have doped out what i need how to do but i seem to be confused on one step.

so here goes: are you suppose to take into account the thickness of the tread on all risers or only the first ( the one that touches the ground,this 1" thickness cut from the bottom edge of stringer)
example: riser should be 7 1/2 ", tread thickness is 1" therefore each riser cut is 6 1/2" with an 11" run.


Termite 06-08-2008 11:52 AM

I'd suggest drawing yourself a dimensioned picture of the stair jack you're going to cut. That usually makes it more clear.

Your riser cuts will all be equal, except for the bottom one, which is cut shorter by the thickness of the tread. Every other rise incorportates two tread thicknesses.

If you haven't, get yourself an L-shaped framing square to make the layout easy. They're about $12. Clamp a scrap of lumber to the 11" mark on the long side and the 7-1/2" mark on the short side. That scrap of lumber rests against the edge of the 2x12, and you trace the exposed angle on the 2x12. At the bottom of your layout, I'd suggest laying out the bottom rise normally and then marking and cutting the tread thickness off.

Be sure you've measured from the top landing to the bottom landing and divided by the number of risers to ensure that 7-1/2" will be a good measurement. You definately don't want a rise variance. Rises and runs are required to be consistent with no variance greater than 3/8" between any two rises or runs on the stair.

FISH96 06-08-2008 12:55 PM

laying out stair stringers
thank you. i have all the tools i require, i double checked the math. your explanation is clear and lucid. this stair erecting will be a challange and fun. both sets of stairs will be for a deck. thank you again.
regards ans enjoy the balance of the weekend,

gregzoll 06-08-2008 07:20 PM

There are actually calculators out on the Web that will help you in the math. All you need to know, is the Height from the Floor to Ceiling, and aprx. how far do you wish them to be . This may help a lot better

scottm 06-12-2008 11:26 AM

Unless I'm wrong, the math is pretty simple & straightforward.

First, calculate the total height of the stairs (from the ground to the top of the deck). For instance, 27 inches. Begin by dividing roughly by 7 - (approx: 3.857). Since you can't have .857 steps, round up to 4. So you're going to have 4 steps. Next, calculate how much the rise is for each step. Take 27 (inches) and divide by 4 (steps). This will give you 6.75 - so this means the rise will be 6 and 3/4 inches.

In the end, the stringers should have 4 steps @ 6 3/4". You're average tread ranges from 9" to 11". This is up to you really. Also take into account for the 1" bullnose for each tread (1" over hang per step).

Note one last thing - since you know you'll have 4 steps, you must subtract one step for the top of the deck. In the end, each stringer will have 3 steps. You could have 4 steps in the stringer but the top step will be coplanar to your deck and may look (& feel) slightly odd.

One thing worth to note as well, if you used 2x8's as boxing for the base of the deck then you'd want your tread to match & come up flush to the top of the deck. Since a 2x8's real width is 7 1/4, you may want to consider the rise be 7 1/4" to match. 'sup to you.

This at least should get you going.

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