Thread: outdoor stair stringers

A set of these and a framing square might help https://www.bunnings.com.au/empire-1...-pack_p5660549

Set the rise on one leg of the square, run on the other and just move the square along for each tread

Originally Posted by blinger

Hi all
I am about to start building some stairs outside.
I have purchased the timber. I am using 280 x 45 treated pine for the stringers.
I have been looking online at calculators to assist in marking out the stringers for cutting.
'Blocklayer' is a site that has a caculator that appears pretty good but I really am struggling to understand how to mark out their measurements on the stringer. (See below).
I am hoping someone out there has a fool proof method for this procedure.
The overall rise is 1850mm and the verall run is around 3000mm.
Am interested in your thoughts.
Cheers
Blinger





Running Stringer Points (up stringer) To under-side of treads ~ Adjusted to allow for 45mm tread thickness and 0mm riser thickness
233, 551, 869, 1187, 1505, 1823, 2142, 2460, 2778, 3096Mark-out

Running Stringer Points (up stringer) To under-side of treads ~ Adjusted to allow for 45mm tread thickness and 0mm riser thickness
65, 383, 701, 1019, 1338, 1656, 1974, 2292, 2610, 2928Mark-out

Total Rise Ideal Rise 115120125130135140145150155160165170175180185190195200205210215220 Possible Rises 9 of 205.610 of 18511 of 168.212 of 154.213 of 142.314 of 132.115 of 123.3 Stair Width Use Ideal Run Use Total Run Use Stair Angle Stringer Width (or) Concrete Thickness Tread Thickness Riser Thickness Nosing Show Headroom Floor Thickness

ColourRestrictLabel DiagramEmail Calculation

10 Runs ↔ 270

11 Rises ↕ 168.2

Simple, that number(green) explains it perfectly.

It may be easier if you read a little about Pythagorus or right angle triangles. Then the figures given in Blocklayer will make more sense.

I went to "Blocklayer" and entered:

Total Rise: 1850
Possible Risers: 10 of 185
Use Ideal Run: 250
Stringer 280
Tread Thickness: 45
Nosing: 30

There for:
a = 185 (rise 140 +45)
b = 250 (run)
therefore
c = 311 (hypotenuse)

So you'll notice each point is 311mm apart. e.g. 546 - 235 = 311 and 394 - 83 = 311

Take note of the difference between the two drawings and thus the difference in figure calcs. Drawing one retains two right angle triangles, one at each end whereas drawing two discards them because they're not needed for the final shape of the stringer.

Blocklayer only seems to be able to create a "Cut" stringer whereas the treads sit above the stringer and not "housed within it but you can sort of trick it up by altering the tread thickness but then you'd require another albeit easy allowance when marking your stringer.

Hope that makes sense?

Here it is set out for you. Any questions feel free to ask

It's one of those things that you don't realise how complicated it is until the first time you try to do it, thinking it's easy of course.
Once I've done one side, after checking it for correctness, I copy the other side from the first. Those little jiggers Elan linked to would be a good aid.

Originally Posted by blinger

Hi all
I am about to start building some stairs outside.
I have purchased the timber. I am using 280 x 45 treated pine for the stringers.
The overall rise is 1850mm and the verall run is around 3000mm.

hi, rwbuild has done the layout for you, based on a 3000 mm run.

Can I suggest that you check what the actual run is, and that you have measured the total rise from the base of the run, and not directly below the landing.
If the ground under the stairs slopes, the total rise includes this slope, see attached

Hi Ian
Thanks for your reply.
Yes I did measure the rise at the bottom stair landing point as you suggest.

Hi rwbuild.
Thanks for your reply.
I am wondering how you arrived at a rise of 213 and a run at 345.
The treads 116 x 45 so I thought I would lay 2 treads with a 20mm gap in between and a 20mm nose projecting. This would require a run measurement of 252 (will do 250 for ease of marking) with a 20 overhang.
The rise of 213 I imagine includes the 45 thickness of the tread.
The overall run is pretty close to where I had measured.
I really appreciate the help this forum provides.
Cheers
Blinger

Thanks Aldav

Thanks Springwater.
Will be doing some reading tonight.

Originally Posted by blinger

Hi rwbuild.
Thanks for your reply.
I am wondering how you arrived at a rise of 213 and a run at 345.
The treads 116 x 45 so I thought I would lay 2 treads with a 20mm gap in between and a 20mm nose projecting. This would require a run measurement of 252 (will do 250 for ease of marking) with a 20 overhang.
The rise of 213 I imagine includes the 45 thickness of the tread.
The overall run is pretty close to where I had measured.
I really appreciate the help this forum provides.
Cheers
Blinger

Have another look at the diagram, 154 is the actual rise tread to tread, 213 is from the REAR of the tread to the TOP of the stringer, this is so you can either set up a carpenters framing square or use a template because ALL the set out is done from the TOP EDGE of the stringer so that you have a 50mm offset to the housing for the tread to be fixed in place
DON'T FORGET TO MIRROR REVERSE THE SET OUT ON THE OPPOSITE STRINGER

Ahh I see. Thanks rwbuild

The code requires a 10mm threaded rod every 1800mm (measured on the slope of the stringer) to stop the stringers spreading regardless of nails or screw fixing of treads to stringer. It is usually placed under a tread with the nut and washer countersunk into the outside edge of the stringers.
In you case, 1 at the bottom and 1 in the middle and one under the last tread at the top. They MUST be galvanized.
The depth of the housing for the tread in the stringer is max 1/3 thickness of the stringer but common practice is 10mm (minimum) or 12mm