Step 1: Tools and Supplies
1- Hand Saw
3- 16d Nails
4- Framing Square
6- Tape measure
Things to make life easier:
1- Circular Saw
2- Jig saw
3- Nail Gun
4- Stair Gauge
5- Board Bender
6- String Line
7- Chop Saw
Now for the supplies. I can't tell you the cost of the project cause honestly I don't know. We just went out to the yard with all the wood and just started building. Kinda the perks of building in the Seabee's, you have all the wood you need. But anyways.
At least 6 good, straight, uncracked 2x12x16-They really do have to be pretty much perfect otherwise it will cause headaches later.
Step 2: Math and Measurements
The good news is though that there is a easier way to do the math without finding exact numbers for applications like mine. Basically find the finish height which is from the ground to the top of where you want the stairs to go. For me this number was 84", the height of a 7B Hesco. Now divide that number by 7, the height of the average step. For me I got 12 steps exactly. Other applications may get more or less steps or maybe even a half step left over. We will basically just take that off of the bottom step and make it smaller than the rest of them. Or if it doesn't matter just take that half step off completely and say screw it if its for something like a tree house.
Like I said above the average tread height is 7 inches. the average tread depth is 10.5 inches. If you did the exact math you may have something a little different like 7 1/8 and 10 and 5/8 or something. Thats ok, the set up is all the same just a little adjusted.
There are going to be 3 stringers on the stairs and each one is made out of a single piece of 2x12, which is where the stairs get their strength. The outside stringers will be 36 inches wide from outside to outside. So to make that you will need 2 2x6x36 pieces that will be used as a header and a footer and will be demonstrated later. The legs will have a piece of 2x6 across the bottom to keep them spread out and even that will be 33". Also the treads will be made out of 2x12's and they will have an inch overhang on each side of the stringers so they will be cut at 38 inches. The hand rails are sort of custom to each stair case so what I did is cut the 2x6 for the baluster at about 48 inches to be cut down later for the right height.
The legs that go perpendicular to the ground were cut at 82.5" to allow for the finish height and bracing on the ground were cut to 120" which was found using the pythagorean theorem (A^2+B^2=C^2).
Step 3: Set Up and Layout
If you are using the stair gauges make sure you don't put the gauge right on the measurement you need. Off set them a little bit to the outside of it so that you get the fill measurement onto the board and its not cut short.
Time to layout the stringers. Take the square and put the 7 side at the left and the 10.5 on the right and put it on the 2x12 as far to the left as you can get it with the 2 measurements still on the board and mark the outside of the square. then take the mark from the 7" side and carry it straight across the rest of the way. this is the top step and will be cut out later
Now take the square and align the side with the 7" with the 10.5" mark you put and mark it again. Repeat untill you get the desired number of steps.
The bottom step is done similar to the top except for you carry the tread length across instead of the riser length. Since there is going to be a 2x6 on the bottom and at the top as a header and a footer you will need to mark those lines to be cut out to make it flush to the ground. A 2x6's actual measurement is 1.5x5.5 so you will need to mark that on the bottom as shown in the picture and on the top so that its flush to the top of the tread going down the back of it. Also if you had to take some height out of the bottom tread now is the time to do so. just measure from the bottom up and draw a line then put the marks for the 2x6 to be cut in. I'm sorry I forgot to take a picture of what the top looks like with that part laid out so I may have to update it later with it.
Step 4: Cutting
At the same time that one person is cutting the stringers another can be cutting the treads and the header and footer and also the balusters and legs to length. Make sure to check the measurements I mentioned before. I'm decent at math but hey everyone is wrong once in a while right? Once you cut out everything on the stringers its time to cut the let in's on the legs. If you don't know what a let in is its a basically taking the leg and cutting the width of a 4x4 into it and only half of the thickness will be taken out so that the 2 boards set into each other flush(ish). I know it sounds confusing but I have included a picture that will hopefully clear it up.
One thing about the leg that'll be on the ground, remember that there will be a 2x6 at the bottom of the stairs so make sure to make the let in the right size for it and on the right side of the leg. Learn from my mistakes.
Step 5: Putting it all together
Flip the stringers over after you have them all nailed in and layout all the treads you cut on the stringers. I normally wait on the top one till last just cause it a little bit of a pain. Now remember that there is an inch over hang on each side of the stringers. What I do is make sure one whole side is good and nailed in with the right over hang and then go to the other side and try to get it as close as possible. This is where the board bender comes in handy but don't push too hard or it'll break the stringer. After you get the outside ones nailed you can just nail the center one in and not worry too much about if its dead on. Remember to use 3 nails in each stringer when putting the treads on.
If you want to put these up without being self standing this is when you can do so. Just nail it up to whatever it is your putting it on and then add the top tread then skip to adding the railing
Its time to add the legs onto it. Its easier to have someone help you hold them in place while you nail them in place but you can also take scrap blocks and nail them in place (to where you can still get them out mind you) so it is held up while you nail it. I put about 5 in each side of it that were touching the stringer and the header and then 2-3 through the top of the step just to make sure. when you put the legs on make sure the let ins face the inside as pictured, they can face out but its more or less for looks to have it face in. Nail it in the same way as the other legs just make sure its flush. when you nail the let ins together nail one side then nail from the opposite direction and do that with 4 nails, 2 on each side.
Step 6: Putting it all together pt. 2
You can either take a tape measure and measure from one top side to the bottom and cut the angle for it, or do it the lazy man way and take a 2x4 and lay it against it and mark it and cut 2 of them. Either way it gets the job done.
The hand rails can be done one of 2 ways. You can add a piece of wood to the stringer and nail it that way, which to me is kind of sloppy. Or you can cut it into the step even with the stringer and nail it straight into the stringer like I did. I feel its more sturdy and looks cleaner.
Depending on the number of steps you may need more or less balusters or just how confident you are in them can determine that. I used 3, one at the top, one in the middle and one at the bottom. If you didn't cut these pieces do so now.
If you decided to cut the baluster into the step find the middle of the step and measure half a 2x6 on either side of it and cut it out but remember that there is only an inch overhang and the 2x6 is an inch and a half thick. once you cut it out take the pieces you cut and flush it to the bottom of the stringer at the bottom and at the top and middle put one corner at the bottom of the stringer but don't overhang it. Yet again not for strength but for looks. When you nail these in one thing to remember is you want to nail it with the nails going opposite directions. Not like the let ins, but one angled up and the other angled down. What this does is it causes the nails to oppose each other so its not as easy to push it out as all straight nails would be.
Once you put the balusters on take a tape measure and mark a comfortable height for the hand rail n the top one and the bottom one. Then take a string line and put it on the 2 marks and pop it. and now you have a nice even angle that takes out all the guess work of it. Just cut that off and measure from the tip of the top one to the other side of the bottom one and add 2 inches for over hang.
Cut 2 2x4's to that length and then nail one to the outside the outside of the rails flush to the tops. Then take the second and line it up to the top and bottom and flush it up to the outside of the first 2x4.