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yournamehere · 07-14-2009, 04:41 PM

In your case, you have 9 risers spanning 5 feet, so each riser is 6-2/3"
You have 8 treads spanning 8 feet, so each tread is 12"

There are three general rules for Riser-Tread Ratio:
1. Rise plus tread width = 17” to 18” In your case, 6-2/3 + 12 = 18-2/3" A little on the high side.
2. Rise times tread width = 72” to 76” In your case, 6-2/3 x 12 = 80" More than a little high
3. Sum of two risers plus tread width = 24” to 25” In your case, (2 x 6-2/3) + 12 = 25-1/3. Again - a tad high.

The ideal angle for a stairway should be 34-37 degrees. Yours is 32 degrees - on the shallow side.

The "ideal" stairway has 7-1/2" risers and 10" treads.

Is there any way you could extend the deck another 26"? If so, that would give you eight 7-1/2" risers and seven 10" treads.
1. R + T = 17.5 Check
2. R x T = 75 Check
3. 2R + T = 25 Check
Angle = 37 degrees Check

Now - all that being said, I don't think the sky would fall if you built it the way you've drawn it. It's just a little on the shallow side, with less than average riser heights and longer than average tread widths. That's better than having them both too high or too low - another general rule is "the lower the rise; the wider the tread." Besides - none of the dimensions are really out of whack. And if you're building it for people with big feet who don't like lifting them very high - it's perfect.

However, if the brick columns are drawn accurately, I don't see a problem cantilevering another 26" of joists over them. If you want, you could just extend a 26" "platform" out to the stairs. However, to be on the safe side, I'd put some vertical 4 x 4s under each outside joist where they meet the top of the stringer. Or - you could put the 26" platform at the bottom - you'd use a lot less 4 x 4 that way, but the slope of the ground might make it a bit dicier anchoring them.

My 2 cents.
Good luck!

And yes - let's see a photo of the finished deck!

07-14-2009, 04:41 PM	#6 (permalink)
yournamehere Invisible Location: tentative, at best	In your case, you have 9 risers spanning 5 feet, so each riser is 6-2/3" You have 8 treads spanning 8 feet, so each tread is 12" There are three general rules for Riser-Tread Ratio: 1. Rise plus tread width = 17” to 18” In your case, 6-2/3 + 12 = 18-2/3" A little on the high side. 2. Rise times tread width = 72” to 76” In your case, 6-2/3 x 12 = 80" More than a little high 3. Sum of two risers plus tread width = 24” to 25” In your case, (2 x 6-2/3) + 12 = 25-1/3. Again - a tad high. The ideal angle for a stairway should be 34-37 degrees. Yours is 32 degrees - on the shallow side. The "ideal" stairway has 7-1/2" risers and 10" treads. Is there any way you could extend the deck another 26"? If so, that would give you eight 7-1/2" risers and seven 10" treads. 1. R + T = 17.5 Check 2. R x T = 75 Check 3. 2R + T = 25 Check Angle = 37 degrees Check Now - all that being said, I don't think the sky would fall if you built it the way you've drawn it. It's just a little on the shallow side, with less than average riser heights and longer than average tread widths. That's better than having them both too high or too low - another general rule is "the lower the rise; the wider the tread." Besides - none of the dimensions are really out of whack. And if you're building it for people with big feet who don't like lifting them very high - it's perfect. However, if the brick columns are drawn accurately, I don't see a problem cantilevering another 26" of joists over them. If you want, you could just extend a 26" "platform" out to the stairs. However, to be on the safe side, I'd put some vertical 4 x 4s under each outside joist where they meet the top of the stringer. Or - you could put the 26" platform at the bottom - you'd use a lot less 4 x 4 that way, but the slope of the ground might make it a bit dicier anchoring them. My 2 cents. Good luck! And yes - let's see a photo of the finished deck! __________________ If you want to avoid 95% of internet spelling errors: "If your ridiculous pants are too loose, you're definitely going to lose them. Tell your two loser friends over there that they're going to lose theirs, too." It won't hurt your fashion sense, either. Last edited by yournamehere; 07-14-2009 at 05:34 PM..