Deck Stairs how to build stairs

I'll run through quickly how I constructed these stairs for a barn project I did earlier. I also made up a stair chart so you will have a reference to the total rise (overall height) to # of risers without all of the math click on the link above.

To see how I frame for decks to make putting in the posts and the first drop riser
easier look at the Petaluma 4 Level Deck Project.

The math:
For the total rise measure from finish to finish or rough to rough.. in this case from the top of the decking to the top of the concrete landing we'll call that "X".

In my example above right X gave me 78" I wanted 7" risers for each step so divided that into 78" and got 11 (risers) @ 7 1/8. The deck is the top riser so I have 10 risers at 7 1/8. 10 X 7 1/8"= 71 1/4"

Your calculation would be X divided by 7= number of risers ( # ). Round up if over .5 or down if under. Now take X and divide it by # and you'll get the exact height of each riser. If it isn't close enough to 7" risers take your # and add or take away a riser... the best way is to just use the chart I provided.

There is always one less tread than a riser so 10 risers and 9 treads.

I wanted a 10 1/4" tread (2 - 2x6's with a 1" nosing: the tread overhang) so the total run would be in my example 9 treads X 10 1/4"= 102 1/2" Note: The decking on the stair tread is 11 1/4" the tread cut on the stringer is 10 1/4" so you will have a 1" nosing .

A tip to determine the exact total rise is to place a level straight 2x4 out from the deck and measure down at the total run.

NOTES: If you are using 3/4" riser like I do remove 3/4 of an inch from the top of the stringer see the drawing above.
Cut the bottom riser 1 1/2 inches shorter than the rest to compensate for the tread depth see the drawing above.

Now take your stair clips and set them at 7 1/8 & 10 1/4 inches and mark off the # of risers & treads, I use 2x10 treated for the stringers. I use 3, one in the center as well whenever I get over 3' wide. Put the crown of the stock to the saw tooth side of the cuts, (curve up).

The bottom of the stair stringer need to have the thickness of the tread removed from it so set your square like above and mark at the 1 1/2" then cut that off on the horizontal. That will make that first step equal to all of the others,also if you use 3/4 riser material cut that from the top of stringer on the vertical.

Cut on your lines and you can knock that "tooth" out then go back and cut out the piece left with a jig saw. Then you can use that stringer to copy onto the other two and cut those after you've tried it in place. This is what the top of your stringer will look like, I'm cutting on the tread (horizontal) above.

Now copy the top & bottom of the stringer onto the 2x12 treated skirt (back-up stringer). Once you have that reverse your square and at the first rise (bottom) mark out from the riser the thickness of the riser material ( I used 3/4 cdx siding ), and also the nosing projection 1" for a total of 1 3/4".

At the top of the skirt run the cut (vertical line) past the top tread to the top of the stringer. Later you'll set it in place flush with the bottom of the placed stringer placed and mark the bottom of the decking or top of the deck skirt dependent on how you finish your decks.

If you have looked at the Petaluma Deck Projects framing you'll be able to nail in blocking at the deck to hold the ledger which you will attach the top of your stringer to. Project the blocking down the height of the ledger ( I place them a min. of 12" o/c ) and double the outside supports or use 4x4, you can extend down the ballusters (deck railing newels) post as well for those.

To attach the stringers I use framing anchors screwed rather than nailed, 2 on the center and 1 on each interior of the outside stringers, then I also attach a left and right H2.5 tie to the outside of each stringer. Then I screw in from the back of the ledger or screw in from an angle (toenail) from the front. The tops of the stringers are 7" or your riser height down from the top of the deck.

Finally...
I use risers to make the stairs rigid & plumb, so place the first riser at the bottom then measure from corner to corner to make sure the stairs are square. Then place the two outside skirts and screw on the treads & risers from the bottom up keeping it all parallel with a gap between the treads a 16d common that will leave you a 1" nosing (overhang).
The newel posts can be bolted right to the sides of the skirts and you'll have a nice sturdy stair that won't bounce or give you noticeable lateral movement.