calculating steps required

[vavet]

I'm trying to plan for a new detached garage. Ideally, I'd like to put in a loft, but I want to make the best use of the space. I don't want to consume a lot of space on the ground floor with steps, so I'd rather avoid a turn in the staircase and protruding into the floorspace more than the width of the staircase.

The variables as I see it are: building width and ceiling height. I'll use a 12/12 roof pitch to maximize the space and match the house.

Assumptions:
12x12 roof pitch, leaves me with a height of 7 foot when I am 7 feet from one wall and 21 feet from the opposite wall.
A higher ceiling requires more steps.
Building code here requires max of 7.75" riser and minimum 10" tread.
Landings must be a minimum of 3x3 foot.

I have a spreadsheet with formulas written, but I can't upload it here.

If I opt for a 10 foot ceiling, how high do the stairs need to be? Is 10'10" a safe assumption, accounting for the bottom chord of the truss and the floor thickness?
If I maximize the staircase pitch while minimizing the landing areas, that leaves me with 21 feet available for stairs out of a 28 foot wide building, working with the assumption that I want a minimum 7 foot headroom at the far edge of the upper landing.
28 feet
- 3(upper landing)
- 3(lower landing)
- 1(width of the block foundation)
equals 21 feet

This gives me 17 steps to rise 130 inches. Maximum rise is 131.75. By adding just 2" (for 11' total), I would require a lower landing, a turn into the workspace, and one more step.

All this works out for me in a spreadsheet, but I'm posting here to gain the wisdom some of you might have from your experience. What have I forgotten?

In case you're wondering, another reason for my aversion to the turn in the stairs is because I want the entry door along the wall aligned with the stairs. It would make taking long stock up the stairs easier if there's only one turn - at the top, instead of having a turn at the top and the bottom.

There it is. That's my plan.
Shoot holes in it for me.
Thanks

 

[RocketScott]

Just some observations:

Total building width is 28' but the space you have for the staircase is less than 21' depending on your wall thickness (to get 7' at the far end of the upper landing). The pitch of the roof starts on the inside/underside of the rafters/truss top cords. The 10'10" assumption depends on trusses or floor joists out of 2x10, that depends on whether you want a beam line going down the middle of the garage.

If you need 17 risers that should be enough room. 17 risers would need 16 treads, the last 'tread' is the upper floor (3' landing).

If you have to have a step or two up to the landing on the inside you could build a stoop outside the door you want at the bottom of the stairs and then a couple steps down from it. You'll need a landing outside that door anyway.

In stead of a spreadsheet try google sketchup.

 

[My Old Tools]

http://www.mycarpentry.com/stair-calculator.html

 

[wssix99]

Building code here requires max of 7.75" riser and minimum 10" tread.
Landings must be a minimum of 3x3 foot.

This gives me 17 steps to rise 130 inches.

Usually codes will give you a limit as to how many steps you can have before you have to put a landing in for rest. (Old people, over the age of 39, need this type of thing. All these steps have me thinking elevator...) So, you may also look to see if your local code has any landing requirements, also.


Taking long stock up and down stairs is a pain, no matter how you do it. Will you be working with it up in the loft or are you just thinking about storage up there? If not working with the stock up top, I'd look for creative ways to store it low. After building my house and garage, I really wish I had the forethought to build special heated storage/compartments/doors for long stock, my 50 foot ladder, etc. so I could just access that stuff and manage it from outside the building but still keep it "in the house."

I also live in a very tall house, which means lots of stairs. Over 25% of the floor space in my house is taken up by the staircase and the foyers/hallways serving it. Anything you can do to minimize the footprint of the stairs will have a big payoff. Could you do something like put a compact spiral staircase inside (for easy/quick access) and have your long/working staircase external to the building? (Built like a deck.) That may also give you more versatility as far as what you can store upstairs. The only drawback is that you'd have to go out in to the elements for moving large/heavy stuff.

 

[rslaback]

I'd start by asking your building inspector if those stair codes are for living space. Quite often storage areas are not limited to the same riser and tread limitations as the stairs between floors in a home.

 

[mikegt4]

Don't forget headroom requirements over the staircase, it's in the code.

 

[TTTTTT]

I did access to my loft from the outside to save interior space also. I put a 8' x12' deck with stairs down to a 3' x 3' landing. I used 3- 2" x 12" x 16'. I lean the 2 x 12 at the top level to the landing and level to determine the best angle where the tread was level. Mine has 14 treads plus the landing. A 10' drop. Mine just fit without a landing part way.


Sent from my HTC One M9 using Tapatalk

 

[Nowater]

Keep the requirements for a mid level landing in the back of your mind for now--could you make a scale drawing of your stairway to answer your questions much better than reading answers suggested by good folks who may or may not understand the situation based on the description provided.

Don't you think a drawing will be needed before you build?

 

[RWorth]

my work space was more valuable than the ability to have the stairs inside so I also did an outside staircase. If located properly you can back your truck right up to the stairs. And there is no limit to the width of the treads making moving large objects such as pool tables and Kegs easier.

 

[vavet]

I considered outdoor steps, but my concern was the longevity and maintenance requirements of that. Those who have outdoor steps - what has been your experience with this?

 

[bczygan]

Outdoor stairs, covered or completely enclosed, 4' wide with straight shot into the length of the upper floor. Then you can increase the tread and minimize the riser without worry, and make it an easy access.

 

[DonPowers]

Sometimes you just have to give up some space. I wanted to have a staircase that would make it easy for getting stuff up to and down from the second floor. Went with 4 ft wide with 7.5"rise and 10.5 Tread. My ceiling height is 11 ft and the second floor trusses are 2 ft deep. Most codes also require a landing at 12 ft so I made a long landing going from the top of the stairs to the end of the building which gives me one step up to the floor with plenty of room to maneuver things.

Good luck with your design.

 

[tomroblee]

I'm not sure I understand your language and/or math.

It sounds like you want a 28' wide building (outside dimensions) with a stairway going the width of the building.

It sounds like you are saying the inside dimensions of the building are 27' wide.

It sounds like you want the stairs to start 3' inside the inside of the wall on the ground floor.

If you want 7' headroom at a point the is 3' beyond the top of the stairs (in your loft), the "landing" at the top of the stairs is going to be roughly 10' from the far wall. (With a 12/12 pitch roof, you won't have 7' head room until you are 7' into the loft.)

My math shows:
28' outside dimensions
- 1' lost to walls
- 3' bottom of stairs
- 10' top of stairs
= 14' (or 168") room for stairs
/ 10.5" tread width
= 16 steps

It sounds tight to me. There could be a few inches slack if the stair treads are allowed to "overlap" the risers slightly.

You didn't mention whether the staircase was going to be open or enclosed, and/or what kind of handrails you were intending to use. These items will affect how easy it will be to make a turn at the top of the steps--especially if you are carrying a long and/or bulky item.

 

[Jlbc212]

I considered outdoor steps, but my concern was the longevity and maintenance requirements of that. Those who have outdoor steps - what has been your experience with this?

I did the outside steps too. Placing the stairway inside would eat up too much valuable garage space. I used pressure treated lumber for the stair stringers and treads and fir for the rails. Stained it with a semi-transparent stain.

 

[wssix99]

I considered outdoor steps, but my concern was the longevity and maintenance requirements of that. Those who have outdoor steps - what has been your experience with this?

Pressure treated is a pain to keep up with, but if you spring for composite treads and railings, those parts will last longer than you will!

 

[Gerald O]

When calculating the run of a flight don't forget to factor in the nosing. This is the overhang of the tread extending beyond the riser. For example, if you have a 10.5" tread with I" nosing, then the actual run per each step is 9.5" So in this example the total run for 10 steps, not counting landings, would be 95", not 105". Building codes will specify the min and max nosing, in addition to riser and tread specs.

 

[jpcjguy]

You could always have the landing up higher. That is what I am contemplating in my design. I am looking at a 36 wide x 30 deep with 12' ceilings and want to use attic trusses. The 12' ceilings makes for a loooong staircase - especially if you don't want turns/landings that eat up floor space.
My thought would be to do something like in this picture on the upper end:

Don't have the lower landing, but have the upper.

 

[jpcjguy]

Sort of like this. Think of the landing a 8-9 high.

 

[Gerald O]

In case you're wondering, another reason for my aversion to the turn in the stairs is because I want the entry door along the wall aligned with the stairs. It would make taking long stock up the stairs easier if there's only one turn - at the top, instead of having a turn at the top and the bottom.

The flaw in that is how you get your long stock around the turn at the top.

You could always have the landing up higher. That is what I am contemplating in my design. I am looking at a 36 wide x 30 deep with 12' ceilings and want to use attic trusses. The 12' ceilings makes for a loooong staircase - especially if you don't want turns/landings that eat up floor space.
My thought would be to do something like in this picture on the upper end:
Don't have the lower landing, but have the upper.

The one concern with that mid landing and turn is whether it hinders getting long materials to the second floor. This depends on whether the upper floor is walled off from the stairwell or open. If it is walled off, then the mid landing with turn actually lets you get longer stuff in. I can get 4x8 sheet materials in around that turn and 12' long boards. The landing and stairwell height let's you make the turn to face into the room above. With just a straight stair run you'd be running into the roof or wall at the top of the stairs.

Pics of those stairs more close to being finished with a better look at the second landing:
http://www.garagejournal.com/forum/showthread.php?t=200759&page=6