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Old 08-31-2015, 03:32 PM   #1
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Stairs


Okay, I have to post a question where I anticipate not liking the answer, but unless there's a legit way around this, then just tell me there isn't...

I'm rebuilding my basement stairs. Currently they are straight stairs with a landing for an exterior door. The new configuration will be a landing at the same height, but an L-shaped stairway with the stairs from the landing to the first floor across from the exterior doorway.

Currently the stairs from the landing to the basement floor are inconsistent riser height (bottom has a rise or 2 or 3") but there are 6 steps not including the landing over a total height of 48.75".

The stairs from the landing to the first floor cover a total rise of 34". There are 3 steps, not including the landing or the floor of the first floor. I haven't measured, but an 8.5" rise seems consistent.

I've done the framing work on the floor joists and was ready to cut the floor, I've got the furthest joist from the door doubled, the next joist cut as a tail joist, and the header along with a support joist, the start of a stud wall which will support the new landing.

So the new opening is framed for up to 2 joist cavities of run - i.e. 32". I was assuming I'd have the same run as the existing stairs, so I'd be using less than 32".

As I go to do the stairs calcs and check code, it looks like to follow code, I would need to jump up to 4 steps, so my stringer would need 34" of run.

I'm concerned I'm going to end up needing to reframe to cut another joist. Obviously I need to remeasure when I get home to see if that's the case, but what are my options? Here's what I can think of, knowing not all of these necessarily comply with code:
1) Use the same 8.5" rise as current steps (not to code? The question <or wishful thinking> I have here would be, is this possibly granfathered)
2) Cut another joist for a longer stairway opening in the floor (would have to move more plumbing and electrical again plus some built in shelving in the basement I was going to move anyway, but much later)
3) Raise the landing. To do this, I could just add a cement step outside the door. The door has to be moved anyway. But the driveway goes right up to the house, I think it's wider than it has to be and wouldn't be an issue since I keep the garbage cans next to the house without running them over - even when backing in a trailer.
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Old 08-31-2015, 08:23 PM   #2
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Stairs require very specific information: total run for all treads + landing, total rise (floor to floor), stair layout, width, landing size (LxW), photos. We've chased our tails on questions like this in the past, which is why I ask.
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Old 09-01-2015, 02:39 AM   #3
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Quote:
Originally Posted by keymaster View Post
Stairs require very specific information: total run for all treads + landing, total rise (floor to floor), stair layout, width, landing size (LxW), photos. We've chased our tails on questions like this in the past, which is why I ask.
+1 I am pretty good at this and would like to answer your question but with the info provided and the way it's stated I don't have a clue.some of the terminology is wrong but that is expected on a DIY forum .A few pics with dimensions or simple drawing would probably get you some answers.
Rise /run of each set and the elevations of the landing are a must.Would also need to know the width which in most areas is a minimum of 36".

Last edited by mako1; 09-01-2015 at 02:47 AM.
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Old 09-01-2015, 08:40 AM   #4
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Adding a picture with dimensions of the current configuration. As you can see it's a straight stair. The opening at the top of the stairs is going to be closed off, it currently goes into the kitchen, the kitchen is moving to the other side of the house and a bathroom will be in that area.

The hard limitations on what I'm building would be that I can't change the basement walls (left side of image) or the triple 2x8 beam (right side of image) and I can't change the width of the existing stairway opening in the first floor.

The basement is 72" floor to the bottom of the floor joists, maybe a fraction of an inch less. Nothing I can do about that either within the scope of this project.
Attached Thumbnails
Stairs-basement-stairs-lower-view-current-view-dimensions.jpg  
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Old 09-01-2015, 08:46 AM   #5
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These are rough sketches of the changes, and a plan view diagram of the changes to the first floor structural changes. (The diagram is not to scale of course)
Attached Thumbnails
Stairs-basement-stairs-upper-view-remodel-plan.jpg   Stairs-basement-stairs-lower-view-remodel-plan-25-.jpg   Stairs-revised-construction-l-shaped-stairwell-opening.png  
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Old 09-01-2015, 08:55 AM   #6
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On the outside, currently there's 7" from the driveway surface to the exterior door threshold.

My current thinking is that the best solution is to build the new landing 4" higher than the current height. That would result in the same number of steps I currently have below and above the landing with a consistent rise of 7.5" per step.

Currently, if the steps below the landing were even it works out to a 6.8" rise and the steps above work out to an 8.5" rise.

A 6" concrete block step under the exterior door on the outside would be a reasonable solution.

As to the stairway reconfiguration, besides it being necessary due to the bathroom, by moving the bottom of the stairs away from the exterior wall, it improves a head clearance issue (bottom step is currently just under the end of the existing opening under the stairs to the second floor, which can sort of be seen in the pictures) and I don't really like how close the bottom of the stairs gets to the wall, especially considering that the water meter location. (If something heavy was being moved down the stairs and was dropped, it could hit the meter, possibly rupturing the incoming water pipes.) Plus the existing stairs aren't built with a consistent rise.
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Old 09-01-2015, 09:03 AM   #7
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Here's where things are at right now. The first floor structure is ready for the opening to be cut, the existing stairs removed and the new stairs built.

On a side note, I am considering a larger exterior door... 36" would be ideal, but I know that I'm limited because of the landing width and a 32" door might be what I have to go with. Only reason to stick with the 30" door is to save money by reuse.
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Old 09-01-2015, 09:16 AM   #8
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Quote:
Originally Posted by keymaster View Post
Stairs require very specific information: total run for all treads + landing,
That would currently be 90". The new L shaped configuration would give some room for the run for the stairs below and above the landing to grow.
Quote:
total rise (floor to floor),
82-3/4"
Quote:
stair layout,
Currently straight stair, after the remodeling L-shaped
Quote:
width,
I think the current tread width is 32", I didn't specifically measure it this morning, just the landing. It is what it is. The new stairway opening above the landing has been built to accommodate a 36" tread width.
Quote:
landing size (LxW),
Currently 38"x35". I have some flexibility with the new landing since it is not built yet.
Quote:
photos. We've chased our tails on questions like this in the past, which is why I ask.
Hopefully the photos above are adequate.

In terms of timeline, I'm expecting that over this week and next I'll pick away at removing small pieces, like the edge moldings on the stairs, and cleanup from work already done,but save the bulk of the work until the weekend after labor day.
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Old 09-01-2015, 10:04 AM   #9
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Looking at the numbers as far as run, I had done my baseline planning based on using the same run, but it looks like a 10" run per step would work out pretty well, and if I measure my new opening I can adjust to have a consistent run above and below the landing. I should have no difficulty meeting the 9" code minimum.

Overall, this will mean:
- I increase clearance from the bottom step to the basement wall to 46" (currently 30")
- Overall run for the stairway from the landing down to the basement increases to 60" (currently 48")
- Overall run for the stairway up from the lainding increases to 30" (currently 28")
- Landing is 36x35
- Overall rise remains the same 82 3/4, but now I have a consistent rise of 7.5" per step. The landing moves up about 4". Strictly speaking, that leaves me 1/4" not accounted for, so I could go 7 5/8 on 2 of the steps to make that up and still be within the 3/8" allowable variation. Maybe I'll shoot for a hair under 7 5/8 on the 3 steps above the landing. 7 19/32 would leave the top step at 7 15/32.

For finish, I'm figuring on tiling the stairs. So no tread overhang past the risers. 12x12 tiles 0.31" thick with 1/2" Durock backerboard, so I need to accommodate that plus thinset thickness in my stringer calculations and the height I build the landing to.
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Last edited by WillK; 09-01-2015 at 10:12 AM.
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Old 09-01-2015, 02:07 PM   #10
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Quote:
Originally Posted by WillK View Post
(Total run) That would currently be 90". The new L shaped configuration would give some room for the run for the stairs below and above the landing to grow.

(total floor-to-floor rise) 82-3/4"

Currently straight stair, after the remodeling L-shaped

The new stairway opening above the landing has been built to accommodate a 36" tread width.

(landing) Currently 38"x35". I have some flexibility with the new landing since it is not built yet.
That's a lot of replies. I'm going to try to help you by spelling out what the code will allow you do to do. Try to keep your response to one post, if possible. (It's difficult to sort through it all when it carries over multiple replies.)

1) Generally, "grandfather" protection pertains to the current stair only. Rebuild it, and you need to bring it up to code.

Then, assuming 2009/2012 IRC adopted in your locality in MI (check with building dept.)

2) Max riser is 7-3/4".
3) Min. Tread width is 10" from nosing to nosing.

11 risers of 7.5" (or 12 risers of 6.89", but no advantage there).

9 treads + landing. Landing needs to be a min. of 36" long x 36" wide.

9 treads of 10" = 90" + 36" landing = 126" total run.
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Old 09-01-2015, 03:58 PM   #11
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My only concern with that is the landing. I can make the landing platform 36x36, but the existing width of the existing stairwell is what it is and a corner of the platform would be covered and have the support post sticking through it. Short of replacing the stairway to the second floor, the opening to the first floor isn't going to change.

I thought code was that the platform needs to be as wide as the door width.

I'm not sure if I'm finding the latest or I know for certain what's adopted, but my read of what I had found for Michigan building code which was adopted in 2008 stated 9" min. tread width nosing to nosing. But I don't see an issue with 10" at any rate. State of Michigan's website references 2009 Michigan residential code, which the description on the ICC site that Michigan refers you to for purchase states that it integrates the 2009 IRC.

My local government wouldn't have adopted anything newer than the state. It's been 5 years since I checked, and the city has taken down the page they had listing the codes they reference.

The bottom line for me was whether or not I'd have to cut the joist I just doubled up, and it seems the answer is no if I raise the height of the landing (and it sounds as if that's an acceptable solution.)

ETA: Okay, tread width question now: I found the following guide to 2009 IRC and it states that a 1" nosing is required unless you have a m inimum tread depth of 11". I was figuring on building the stairs without nosing because they would be tiled on the tread and riser.

http://www.precisionstairsystems.com...copy_1__1_.pdf

Am I interpreting correctly by reading that I could angle the riser as in the diagram I'm attaching:
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Old 09-01-2015, 07:17 PM   #12
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it is measured from leading edge to leading edge never riser to leading edge
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Old 09-01-2015, 08:00 PM   #13
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Quote:
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My only concern with that is the landing. I can make the landing platform 36x36, but the existing width of the existing stairwell is what it is and a corner of the platform would be covered and have the support post sticking through it. Short of replacing the stairway to the second floor, the opening to the first floor isn't going to change.

I thought code was that the platform needs to be as wide as the door width.

State of Michigan's website references 2009 Michigan residential code, which the description on the ICC site that Michigan refers you to for purchase states that it integrates the 2009 IRC.

The bottom line for me was whether or not I'd have to cut the joist I just doubled up, and it seems the answer is no if I raise the height of the landing (and it sounds as if that's an acceptable solution.)

ETA: Okay, tread width question now: I found the following guide to 2009 IRC and it states that a 1" nosing is required unless you have a m inimum tread depth of 11". I was figuring on building the stairs without nosing because they would be tiled on the tread and riser.

Am I interpreting correctly by reading that I could angle the riser as in the diagram I'm attaching:




You're correct. 10" nosing to nosing, 11" tread is fine. The tread should protrude to create a nosing. (The riser doesn't have to be angled, it could be perpendicular, and this is common in residential stairs.)

The landing needs to be as wide as the STAIR, and the stair needs to be 36". The issue with the post would be one for the building department. They can tell you if they would allow a variance there--or they will propose another solution.

Regarding the doubled joist--I can't be sure of the condition to which you refer, but if you follow the "max riser/tread size/stair width" requirements spelled out earlier you should be okay. In other words, don't vary from the code--you can't be wrong. If you must vary from it, talk to the building department first.

EDIT: Also, 7.5" risers will leave you with .25" to spare, which is within the allowable riser variation. Still, I would probably divide it between first and last (1/8" each.)

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Old 09-01-2015, 09:09 PM   #14
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A 36" wide stair from the landing down is not practical due to the 33" wide existing opening in the first floor.

Not to mention that I can't meet the 6'8" head clearance due to the 6' ceiling height in the basement. These are areas I need to be grandfathered for the sake of the rest of the stairs design being brought up to code.

Widening stairs to the basement by 3"would mean widening stairs to the second floor, which would push a bedroom wall, which would drive moving windows. Also it would push the front entry door. Second floor stairs meet the code requirements currently, the issue for the basement is that the foundation wall apparently intrudes more into the stairs. Although I am not so sure the floor is framed properly- no header under the landing. Just a joist 18" long with no support on one end, and no load f ed into it from the landing.

My goal is to get the plan as close as possible to final ahead of starting any discussion. My work hours overlap the building department hours completely, so I need to minimize the amount of design iterations.
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