Headroom on basement staircase

4376 Views 33 Replies 7 Participants Last post by 3onthetree, Jun 5, 2020

capecodmass

Discussion Starter · Jun 3, 2020

Installing 2 winger steps at the bottom of an existing basement staircase because insulating a wall in the basement is not leaving a 36" landing at the bottom.

However, doing so will require me to "create" headroom to achieve the 80" required on these bottom two steps.

The first floor joists that are "in the way" are beneath a tiny closet that is inside the box that is created by the sistered floor joists used to create the stair opening.

1) Can I reduce the two existing floor joists to 2x4's with hangers legally since the span of these 2x4's is so short? I'm guessing the answer is no.

2) Do I have to lose the closet entirely and just open up the rest of the opening?

3) Or, do I just have to give up the bottom of the closet on the first floor by adding some kind of 2x8 "deck" above the floor to keep LL intact?

This is finishing a basement in MA. Can add pictures/dimensions, just not sure what the best grandfathered play is.

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Nealtw

· #2 · Jun 3, 2020

capecodmass said:
Installing 2 winger steps at the bottom of an existing basement staircase because insulating a wall in the basement is not leaving a 36" landing at the bottom.

However, doing so will require me to "create" headroom to achieve the 80" required on these bottom two steps.

The first floor joists that are "in the way" are beneath a tiny closet that is inside the box that is created by the sistered floor joists used to create the stair opening.

1) Can I reduce the two existing floor joists to 2x4's with hangers legally since the span of these 2x4's is so short? I'm guessing the answer is no.

2) Do I have to lose the closet entirely and just open up the rest of the opening?

3) Or, do I just have to give up the bottom of the closet on the first floor by adding some kind of 2x8 "deck" above the floor to keep LL intact?

This is finishing a basement in MA. Can add pictures/dimensions, just not sure what the best grandfathered play is.

Why do you need 2 step high, how much did you have before insulating?
Or are you talking about the bottom of the main stairs?

capecodmass

Discussion Starter · #3 · Jun 3, 2020

3

Here are some pictures to see the challenge.

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capecodmass

Discussion Starter · #4 · Jun 3, 2020 (Edited)

Nealtw said:
Why do you need 2 step high, how much did you have before insulating?
Or are you talking about the bottom of the main stairs?

The pictures I added should help, its the bottom of the main stairs. There was about 30" there before I added the R-5 foam board and 2x4 wall, which even if I left it there bare cement would not qualify as a legal landing as it was < 36".

The two winger steps will work for providing a 36" wide bottom tread facing into the room, and the 2nd step being a 45 into the corner, both will pass the requirement of 10" run 12" in from the corner.

The problem is creating the 80" of headroom above them.

Nealtw

· #5 · Jun 3, 2020

capecodmass said:
Here are some pictures to see the challenge.

You can do just about anything with the floor under the closet.
But the beam would need a post and footing before you hacked that up.

I think if you build the box of the bottom step landing and make the second a pie shape on a 45* you can make it work,

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capecodmass

Discussion Starter · #6 · Jun 3, 2020

Yes, I concur on the building of the winger steps, building exactly how you have shown.

When you say post and footing to support under the closet, are you saying that the wall shown at the bottom of the stairs becomes a load bearing wall and I would need a double top plate, or better, say a 2x6 header with jacks beneath the span or something?

In order to solve for 80" of headroom on the 2nd step, I need to reduce the 2x8's under the above closet to 2x4's. (really could do 2x4.5") so is it steel or engineered lumber and go perpendicular or am still confused about whats best.

Nealtw

· #7 · Jun 3, 2020

Like this.

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capecodmass

Discussion Starter · #8 · Jun 3, 2020

Thanks yes, very clear on how the bottom should be built. It's the headroom problem at the top that I am challenged with. Thank you for your engagement and feedback, the challenge is how to solve for the 80" on the 2nd step.

That's the part I'm stuck on solving.

Nealtw

· #9 · Jun 3, 2020

capecodmass said:
Thanks yes, very clear on how the bottom should be built. It's the headroom problem at the top that I am challenged with. Thank you for your engagement and feedback, the challenge is how to solve for the 80" on the 2nd step.

That's the part I'm stuck on solving.

Yes, All I could see was the beam so I went for that.

If you lay a straight edge up the stare so it is touching all the noses and then measure straight down from the wall to the underside of the straight edge. How much do you have?

And then from the wall to the top of the second step.

capecodmass

Discussion Starter · #10 · Jun 4, 2020

I must be asking the wrong question, I have no questions about the stairs themselves this is only about the headroom requirement of 80" from the 2nd step, which as you know will go right into the corner in the pie shape.

I'm already confident that the winger steps will be fully compliant to code, and capable of getting 36" tread with enough room and maintaining existing rise and run.

I am only asking for solutions to create the headroom ABOVE where the smoke detector is to achieve 80 inches. Thanks again.

carpdad

· #11 · Jun 4, 2020

What I did was not have a 2x4 wall there. Compromised on bit of insulation lost there. I framed the wall short of about 60" and just foam board, straps tapcon into the foundation and paperless drywall.
Yours, first check why triple beam? That does not look like sistered joists. Stairs wells are usually double beam although that could depends on the spans. What other structure is above or near the triple beam?
Anyway, as long as it is just a closet above the double header, you can remove the double header and the short joists going to the foundation(?), and add couple of 2x4 on flat to support the closet floor. Plywood itself is good and the 2x4s are insurance. When removing the current joists/header, don't pull them off in one piece. Cut, drill holes, chisel, whatever, so you can split the lumber in one or two inch pieces along the grain and remove little by little. When nails start to show, remove the remains and cut the nails. Check the rules on winder treads. I am not sure about if you have enough room. Winder treads are unsafe, imo. Can you install a landing, although the beam may be in the way?
With that much work, I don't think the stairs are still under grandfather.

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capecodmass

Discussion Starter · #12 · Jun 4, 2020

Thanks for your response carpdad.
Even if I had full space to the bare cement, the staircase was already "illegal" as it was less than 30". So with or without the wall and insulation, I couldn't leave it alone. You need to have as much room in the landing as the stair width, which is 36-38".

I do have enough room for winder. All you need is 10" run at 12" in from the short side, and full width of 36" which I have.

As for the floor joists, I could use 2x4 on its proper side, but is that legal for that space? And should I just sister them to the existing 2x8, or should I move the double header back above the wall and go perpendicular between the two double beams on the stair well? Thats the part I have no clue what is to code and what isn't.

Bud9051

· #13 · Jun 4, 2020

Apologize for not reading all in detail, but I live in a cape with similar stairs.

The double header across where you would hit your head is basically not load bearing and only there to support the floor in that closet. Where you are thinking of using 2x4' under that closet floor, IMO, remove all and leave just the plywood. Then glue and secure one or two layers of Advantec 3/4". The Advantec is EXTREMELY rigid and would support as needed.

Not sure if you are subject to an inspection or not, but this is not a critical are.

Just my babbling and subject to correction.

Bud

3onthetree

· #14 · Jun 4, 2020 (Edited)

Replacing the 2x10 joists with 2x4 wouldn't be adequate. There is no differentiation in floor framing in regards to the use of the rooms.

You'll have to build a platform above the existing plywood sheathing within the closet. Since the closet walls are probably supported by the existing triple trimmer and opposing double trimmer (not shown, not talking about the double header), you can use the wall studs to support this platform.

After you remove the existing double header and the two joists (leave some joist out flush to your new basement wall), if you want to add a 2x4 ceiling below the plywood it'll be just for show.

Of course this is all based on that you've checked that leaving the triple trimmer still gives you the headroom you need on the new bottom tread.

capecodmass

Discussion Starter · #15 · Jun 4, 2020

Permits were pulled for this project, so there will be inspection. I will check out advantec, would I mount this UNDER the existing plywood floor or in the closet atop the existing plywood?

I agree that 2x4's would be more than enough even for live load calculations, especially with hangers, but its more a question of what the inspector will just look at and say "okay thats fine" vs. getting all insane and telling me to redo the whole thing with engineered lumber, etc.

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House Designer

· #16 · Jun 4, 2020

If your goal is to meet Code so that it passes inspection, then please note this:

"Winder stairs are permitted in the building code as of 2019. The code says the minimum tread width on the inside radius needs to be 6 inches. It also says that the tread depth at walk line of the stairs measured 12 inches in from the inside tread edge must be no less than 10 inches."

You do not meet minimum tread width on the inside radius. Yours is zero inches, but min. tread width is 6 inches.

https://www.askthebuilder.com/how-to-winder-stairs/

Nealtw

· #17 · Jun 4, 2020

House Designer said:
If your goal is to meet Code so that it passes inspection, then please note this:

"Winder stairs are permitted in the building code as of 2019. The code says the minimum tread width on the inside radius needs to be 6 inches. It also says that the tread depth at walk line of the stairs measured 12 inches in from the inside tread edge must be no less than 10 inches."

You do not meet minimum tread width on the inside radius. Yours is zero inches, but min. tread width is 6 inches.

https://www.askthebuilder.com/how-to-winder-stairs/

Thank you , whats left, footing and post so he can cut the beam?

House Designer

· #18 · Jun 4, 2020

My suggestion would be to remove the new stud wall locally that is infringing on the landing. Restore the 30" landing that originally existed and ask the building inspector to grandfather the reduced width landing in as an existing condition that is not easily altered during your remodel.

Another straightforward solution is to rebuild the whole stairway with larger rise and smaller run on each tread. This will likely violate Code also, as there are Code minimums for rise and run. Speak with your inspector and decide which solution they can approve.

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capecodmass

Discussion Starter · #19 · Jun 4, 2020

Great. I hand no idea about the 6" minimum on the inside radius. At most I could probably get 2-3" on the 2nd step, and that would be with the bottom step getting 0" to get the full 36" width.

I honestly may have to go with a spiral staircase to make this compliant, which seems insane and far more unsafe than anything defined thus far.

The existing stair well is only 102" long, with about 100 3/4" between floors, I have no idea what else to do.

Also laughing at myself for calling them winger stairs instead of winders!

capecodmass

Discussion Starter · #20 · Jun 4, 2020

Yes, I think I'll have to give them the choice of:

A) 30" landing with no wall, foamboard insulation, leave existing stairs as is.
B) Permit illegal winder with < 6" small radius side and some oddball flooring setup for the closet.
C) Spiral staircase installed.

Even if I completely removed the closet and opened the stair well all the way open, I would not have legal rise/run min/max compliance along with landing compliance. I could get rise/run compliance, but would create a smaller landing.

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