Stairs Part III: Putting it all together

With the stringers in place (here), the treads complete (here), and the brackets ready, it was time to finish the stairs…mostly. The risers will be installed after they dry a bit more (a few months). And yes, this can be done at a later date if I plan it right (leave enough space behind the treads to install them from the back).

Precise measurements

The normal way…

Over in Easyville, at the worst, you buy a 2×12 stringer, set your square for the rise and run using nifty little brass marker attachments called “stair gauges”, then mark bird-mouths, and cut the stringer. You would do all of this with the stringer laying on the floor before installing it. I initially tried to apply this to what I’m doing – but without the brass markers – and ended up being 2″ out of alignment when I reached the bottom step. In my defense, 6 – 31/32″ is hard to find on a square with only 1/8″ marks on it. And my eyes are getting old. I could barely see the 32nd inch marks. Even a pencil line is 1/16″ wide. I found I was off by 1/8″, due to the pencil line and the imprecise square, multiplied by 16 treads, which works out to about 2″. This is an additive error.

Marking cuts on the stair stringers is not supposed to be hard, but for someone attempting to do it for the first time, doing it unconventionally with live edge oak stringers that have no straight lines on them, doing it while they are in place, and getting the measurements right proved a bit difficult. With live edge stringers, there’s no reference point on the edge of the stringers to place the brass stair gauges. The most important part is to pass inspection, and the number one worry with the inspection is the part of the code that says

no tread can be more than 3/8″ difference in height than any other tread.

So, I used a spreadsheet:

…and then just marked the heights of each tread individually from the floor to the center chalkline on the stringer I had made previously. This avoids the additive error of using the previous mark as a reference. Still, it wasn’t easy – I had to try several times before I got it right.

I had a “centerline mark” on the stringer up against the wall, which I made by snapping a chalkline between the midpoint of the two edges at the top of the stringer and another midpoint near the bottom of the stringer. I made this centerline mark on the smaller stringer because I have more room for error on the larger (outside) stringer. It’s just for reference to make sure the treads / risers aren’t set too close to the edge of the stringer, and this centerline was made on both stringers at the same point.

I made another mark to show the location of the nose of the treads – they all need to line up with each other – I can’t have one set back an inch from the others, that would create a trip hazard.

I mentioned making brackets – they are simple angle iron steel with holes drilled in them for screws. I took the steel over to my friend’s house where he has a tough old drill press. I brought my own brand new cobalt step bit, and drilled lots of holes:

To get the tread heights right, I initially took the total rise (9′ 3 1/2″) from the finished floor to the second floor, and divided by 16 (16 steps, including the second floor), which gave me 6 ~ 31/32″. You might think 31/32″ isn’t much, and I should just round it off to 7″, but when you multiply it by 16 steps, you get 1/2″, which would be a code violation. So these things must be very precise.

I started marking my way down the stringer with a right triangle with tape marking the rise (6 31/32″) and run (10 1/8″) and a level taped to the triangle, but when I got to the bottom, I was off by 3/8″. Grrr. I started from the bottom, and was off by the same amount at the top. Grrr again. So I went back to using the exact height of each tread from the floor – and made sure the floor was level. I used a plumb bob to mark the exact spot on the floor where my tape measure would be precisely vertical and then placed a plus (+) on the red chalk line where the exact tread height should be. Then I double checked each tread height by going back over it and marking the rise and run with the right triangle. I made sure each tread mark hit that plus sign and was exactly level. Very painstaking process, but I think it means my stairs will pass inspection.

The perfect slope for stairs

Ever been to a theater, and walked up the stairs feeling like maybe you should take two steps instead of one? Or to a construction site and felt like the temporary stairs were too steep? One of the theories on proper stair construction deals with the proportions of the human body (see below), and “what feels right” to most people when it comes to stairs. It boils down to the ratio of the rise (height) of each step compared to the run (horizontal tread depth), and most folks agree that a ratio of 7″ rise to an 11″ run is the perfect ratio. One guy says his calculation is 2 rises + 1 run = 25″. So, 7″ + 7″ + 11″ = 25. He says anything within an inch of 25 will be fine. Anyway, no more math, except to say that the rise and run I ended up with for mine is 6.969+6.969+11.00 = 24.938″, which is 24 15/16″, or less than 1/16″ from 25″.

I could have transferred the marks over to the other stringer, but it turns out a standard 24″ level is very precise – once one side was mounted, I just gently tapped the tread until it was level in both directions (front-rear & side-side), making sure the nose of the tread lined up with the second chalk line on that stringer.

Installing treads

After double and triple checking my measurements, it was now just a matter of installing the brackets on the stringers, and screwing the treads to the brackets.

Well…. I say that, but there are a few things to think about:

  1. All the steps need to have their nose aligned, so snapping that second chalk line was required.
  2. But all the steps should have some overhang – must decide how far back from the front of the tread the brackets will go – it has to be behind the risers. So I made a little jig / block to put at the nose, and drew a line at the back to mark the front edge of the bracket location.

Mostly Finished

Here they are:

The risers will just have to wait. Can’t have them shrinking after they are installed; that would ruin everything.

A third stringer?

Probably. I’m just going to use an extra 2×12 I have laying around to support the middle of the treads. I just don’t feel comfortable with a tread that spans 3.5′ with no support, even if it is oak. I bounced up and down on the treads, and they don’t flex much even with my 185 lbs on them, but I like to overdo things. I will simply trace the tread pattern onto it- no real measuring required, and cut little bird mouths into it. It doesn’t need the full cut, just enough to give it a little extra oomph and support the stairs.

Next steps

I need a handrail to meet code, and a bannister around the edge of the second floor. Once complete, we can finally move onto electrical work, plumbing, insulating the first floor, the HVAC system, and then onto finishing everything else, like the kitchen, bathrooms, bedrooms, and closets.


One thought on “Stairs Part III: Putting it all together

  1. This is fantastic. My dad took the LHBA class from Skip in the 90’s and built just the best log home… it was magnificent. I took it a few years ago and now I’m in the process of looking for land. All of this is so extremely helpful!

    Liked by 1 person

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