What does a Stair Saw do?

[Brian Kent]

Sometime in the next year I need to replace a flight of stairs (too steep, too narrow a tread, no nose badly finished with Pergo trim. I have to walk down sideways for my feet to fit.)

I am curious how one would use a stair saw. I have never seen one in person. I think they create a dado, but I don't know what part of the tread that would go on. Is it a dado to fit over a stringer, with a tread overhanging on the sides????

Thanks in advance,

Brian

[Chris Vandiver]

Brian,
A stair saw is used to create a dado in a housed stringer, among other things. This dado accepts the tread and the riser.

[george wilson]

You can only use it while standing on the stairs. O.K.,it also is stopped off by the wooden handle/saw back,so it cuts to a certain depth.

[Joseph Klosek]

If you are talking about making the treads wider, then you will need to remove the entire set of stairs and start over. Since you will be changing the run of the entire staircase.

Just adding wider treads will most likely make them overhang the risers by too much and therefore end up adding to the hazard of using the stair.

What is the rise and run? How far do the treads project over the risers?

You will likely need more than just a stair saw to get this done.

Is this a main staircase or secondary one?

J.P.

[Brian Kent]

Chris, is that the definition of a housed stringer, one that has dados that accept the tread and riser?

George, that sounds like it could come in handy for other dados too.

[Brian Kent]

Joseph, I do not want overhanging treads. I was just asking if that is what the stair saw is used for.

This is my primary staircase that I need to rebuild.

The current rise is 65.5".
The current run is 72".
There are now 9 risers and 8 treads, with no nose on the treads.

I will be adding one or two steps and increasing the run as much as architecture will allow, probably to 106". I'll add a 1" to 1.5" nose on each tread.

I am not planning on using a stair saw, but just wondered what they were used for when stairs were made by hand.

[Brian Kent]

…and i'm just gaining knowledge for now, not making the actual plans.

I just wanted to know what a stair saw is used for.

[Andrae Covington]

Chris, is that the definition of a housed stringer, one that has dados that accept the tread and riser?

George, that sounds like it could come in handy for other dados too.

See housed stringer diagram below. If not an open stair then there would be dados for the risers as well.



source

[Andrew Gibson]

and here all this time I thought they were called stare saws.
The kind like George and others make around here that you could stare at all day.

[greg Forster]

Brian:

with a 65.5" raise, your current 9 risers/8treads is perfect- it gives you a rise of slightly over 7 1/4", the problem is the treads, aim for 10 3/4" run with a 3/4" nosing for 11 1/2" tread width. your total run would be 8 x 10.75"= 86" + the 3/4" of the bottom tread nosing. 1" of nosing is the most you'd want anymore and it will be a trip hazard. I wouldn't add steps
( decrease your rise per tread), with a 7.28" rise and 11.5" run per, you will have a set of stairs with a very nice gait as you ascend/descend them.
Too shallow a rise is as bad as too narrow a tread.
















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[Brian Kent]

Greg, that would sure make it a lot easier to fit in the space.

[Chris Vandiver]

Brian,

One of the "rules of thumb" for stair building is that the the sum of the rise and run for one step should equal between 17"-18". There may be other things to consider but on the face of it, you need to increase your tread depth to a minimum of 9 3/4".
Given the overall rise of your stairway at 65 1/2" with 9 risers, each step should be 7.27".
It may be that you can simply add on 3/4"-1" of nosing but it does depend on how the stairs were constructed in the first place. It is easy to compound errors on stairways. Small errors are often multiplied over the number of treads or risers!

[harry strasil]

In all the old tech manuals I have, the formula is 2 times the rise plus the run = 24.

Some inspectors want each rise to be 7 inches no matter what. I was redoing the rear stair entrance to a local bank and the inspector came around and being that the rise was not exactly 7 inches, he wouldn't sign off. So I just tacked the treads in on the other side of the landing at 7 inche and then told him to close his eyes and walk up them, turn around and walk down, I large step at the top almost got him, I caught him before he went down them head first. He signed off and told me to make them like the first side. LOL

[Gaz Palmer]

Aside from rise and going, head clearance also needs to be taken into consideration if your staircase falls within a stairwell. The minimum UK standard is 6'6" head clearance between nosing height and ceiling and becomes especially important if the floor above overhangs the stair.

[Joseph Klosek]

Are you planning on using hand tools to build the stairs?

Is this a closed stair with walls on both sides? Or open on one or both sides?

J.P.