Stair run


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Old 01-08-14, 06:36 PM
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Stair run

I would like to move the stairs in a cabin we own. The house is a cape with a second floor. Upstairs their is a hallway that runs left to right the enter width of the house. We would like to have the stairs on one end of the house.

We have about 12 feet from the end of the hallway to the front wall of the house. The height from the top of the first floor to the top of the second floor is about 9 1/2 feet. I came up with 13 steps with a run of about 11 feet.

I only have 12 feet. Is there any way to make this work?

Is my math close?
 
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Old 01-08-14, 07:06 PM
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Close. Maximum riser height is 7 3/4". So the figures below use 7.6".

9 1/2' or 114" of rise = 15 steps (counting the landing on top as the last step) and 14 treads. Rise = 7.6", Run = 10". The run for that staircase would be 140" or 11' 8", at a pitch of 39.16°. (33-37° is the most comfortable pitch, so using the above would produce a staircase that is a little more steep than most.)

If you have 12' of run to work with (144"), you obviously need more than 4" of floor to step onto at the bottom of the staircase, so you would probably have to have a landing and turn the last 4 steps 90°. So those 4 steps would protrude an additional 40" or so from the rest of the staircase. If you did not have a square landing, but instead angled the stairs, you would gain some space there, so that the bottom of the stairs did not protrude as far.

You could also consider a spiral staircase.

If you have a drawing that might help.
 
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Old 01-09-14, 04:08 AM
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The stairs will land at a door that is probably three feet off the wall. That will prevent me from having a landing. I like the idea of angling a stair or two at the bottom. Would I build out normal stringers then box out the last two steps?

How do I determine if they will fit?
I will try and post a drawing tonight.
 
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Old 01-13-14, 11:29 AM
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Running tapered treads is a bad idea. Reason being they can present a tripping hazard, even when people have lived with them a while. My elderly mother couldn't use the upstairs stairway anymore, for fear of falling at the angled, bottom landing; Pa set up a bed in the dining room for her.

Even if you're young and agile, some people aren't, and all it takes is one broken hip or ankle to make you wish you hadn't angled those steps. They can also make a property harder to sell come time to unload the place.
 
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Old 01-13-14, 03:46 PM
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Bridgeman, I am guessing that maybe your grandmother's steps were not built to the current 6" minimum inside tread code. Some winder stair treads used to angle down to nothing, which would make the tread pretty narrow should you hug the inside of the staircase going up or down. I agree they would be a bad deal.

Kaw550, what I was imagining you could do would look similar to this.

http://www.nachi.org/forum/attachmen...irs-winder.jpg

Here is the code on winder treads, should you choose to consider it.

311.5.3.2 Tread depth. The minimum tread depth shall be 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Winder treads shall have a minimum tread depth of 10 inches (254 mm) measured as above at a point 12 inches (305) mm from the side where the treads are narrower. Winder treads shall have a minimum tread depth of 6 inches (152 mm) at any point. Within any flight of stairs, the greatest winder tread depth at the 12 inch (305 mm) walk line shall not exceed the smallest by more than 3/8 inch (9.5 mm).
 
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Old 01-13-14, 04:31 PM
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I spoke with my local inspector. I can go up to an 8 1/4 rise.
I ran the numbers and if I go from 7 7/16 up to 8 1/16 I can cut out a step and drop the run by 9"?

I am a little concerned with how I will attach the stringers. The floor joists at 2x6's. The top step will hang down 2".

Can I nail a 2x12 to the face of the floor joist?
 
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Old 01-13-14, 05:20 PM
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Well, that's a question for your inspector. He's already fudging the rules by granting you 8 1/4. According to the IRC, 7 3/4" rise is maximum, 10" tread is minimum.

All questions about rise and run probably need to go through him, since he's got the final say.

As far as attaching the stringers, if you add a 2x12 onto the face of the floor joist (like this), I would recommend that the back edge of that 2x12 should have additional support- the part that hangs below the floor joist could be blocked (framed) back... either level (at least 2 add'l joists) or with a triangle at the same pitch as the bottom of your stringer, provided it can be secured to some solid blocking. It will help prevent the 2x12 from flexing and splitting.

Also, the bottom end of the stringer should be notched (like this) so that it can fit over a kickplate. The kickplate prevents the stringers from sliding down or moving at all... at least at the bottom.
 
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Old 01-13-14, 05:44 PM
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The the top picture is exactly that I was talking about. I plan to put a doorway behind the stairs so that I can use it as part of a small mechanical room. The door for that room will be 4 feet wide (so it extends past the stairs). Can I nail the 2x12 to the side of the header? I may have to pad out behind the 2x12 with a couple more boards to reach the wall.

Will that work?
 
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Old 01-13-14, 05:53 PM
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Sure. If the ledger for your stringer is close enough that it can be attached (or blocked) to a wall that's being built behind there, that would be great.
 
 

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