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| Fix Stairs > Articles | ||||
Stair Stringers or HorsesStair Stringers or Horses Building a simple set of stairs is only slightly more complicated than banging together a child's sandbox. Yet, somehow, stairs seem daunting to many DlYers. I suspect that what really scares people away from building their own stairs, even simple ones, are the angles involved. The key is a little bit of knowledge about determining the length and angle of the stairs you require, and the ability to accurately mark this information on the stair's critical parts; the rest is just rough carpentry. The illustration here shows the anatomy of a simple stair case. The most crucial parts are the stringers, those angled and notched members that support the treads. Designing, laying out, cutting and anchoring the stringers are the main parts of any stairbuilding job and it's these specific tasks that you'll learn about here. Determine Overall Staircase Heist Let's say you need a new set of stairs for your deck. Assuming you can't simply trace the outline of the old rotten stringers onto new wood, or the old stairs weren't comfortable to use in the first place, you'll have to start from square-one. Begin by measuring the height from the top surface of the deck to the spot where the bottom of the stringers will rest on the ground. Do this by dropping the end of your tape measure down from the end of a piece of lumber held out level from the top of the deck. Let's say your deck is 52 1/2-inches above ground level. That's easy enough, but what next? Determine the Rise and Run of Each Stair Tread In stair building jargon, rise refers to the height of each individual stair tread above or below its neighbor, and run describes each stair tread's front-to-back width, ignoring any overhang along the front of each tread. For safe and comfortable stairs, the following conditions must be met: Condition#1: The cumulative height of the entire staircase-that is, the rise of all the stairs added together-must be identical to the overall height measurement, in this case, 52 1/2 inches Condition#2: The front-to-back tread width plus the height of each stair must equal 18 inches, with the rise figure being somewhat smaller than the run figure. I call this the 18-inch Golden Rule. Following this rule assures a staircase that's comfortable to walk on and safely proportioned-not too steep, not too shallow. Let's turn to our example and try to satisfy condition #1: Ballpark the number of treads you think you'll need to lift you up from ground level to the top of your 52 1/2-inch-high deck. Let's try six. Divide the 52 1/2-inch overall rise by six stairs to get an 8 3/4-inch rise per step. How does this compare with other stairs in your house? Perhaps a bit too steep? Fine, let's try seven steps- 52 1/2 inches divided by seven stairs gives you a 7 1/2-inch rise per stair. That's better. Seven steps, each with a 7 1/2-inch rise will get us up onto the deck easily. In practice you'll find that most comfortable stairs have a rise of about 6 1/2 to 8 inches. Now, what about the front-to-back width of each stair tread? This is where condition#2 comes into play. To get to the Golden Rule of a total of 18 inches for the rise and run, simply subtract 7 1/2 inches from 18 inches, leaving you a run of 10 1/2 inches. That's it. All the mind-numbing stuff is done. Laying Out Stringers You won't need anything other than an ordinary carpenter's square and pencil to apply the rise and run figures you've arrived at to the stock for your stringers, but before you do, you'll have to get some wood worthy of the challenge. Construction-grade spruce or pine 2 x 12s are the usual stock used for making staircase stringers, though you can probably get away with 2 x 10s for shorter staircases involving only a few steps. The crucial thing is that the wood be sound, relatively clear and have no large knots. By the time you cut notches out for the stairs, there will be quite a bit less wood in a stringer than when you started, so be sure that what's there is good. Two stringers are okay for utility stairs up to 32 wide, but I'd go with three stringers for anything wider. A good rule-of-thumb is one stringer for no more than a 32 stair width. The second illustration shows you how to hold your carpenter's square over the stringer stock to mark the outline of each stair. Notice how the 7 1/2-inch point along the left side of the square is lined up with the edge of the lumber while the 10 1/2-inch spot on the right side of the square lines up with the same edge. These are, of course, the rise and run figures we calculated earlier. Applying them to the stringer stock in this way, using the carpenter's square, automatically creates the correct angle and orientation we need. I don't even know the angle (in degrees) of the resulting stairs, and I don't have to. The square takes care of everything. Remember how we settled on seven steps for our example? The actual stringers we'll create for a job like this will only have six stairs, because the seventh stair, the top one, is actually formed by the upper surface of the deck itself. Also note that the bottom-most step is actually closer to the bottom of the stringer than the rise figure. This reduction in height must match the thickness of the stair tread you'll be adding later, usually 1 1/2 inches. Cutting, Fitting and Installing Stringers Cutting stair stringers is a job that requires precisely-stopped cuts through thick stock. I like to use a combination of handheld circular saw (to do the bulk of the work), and a jigsaw or sharp handsaw to finish the last bit of the two cuts that intersect to form the inside corner where one part of a stair meets another. Using a circular saw for the whole job will result in overlapping cuts that will weaken the stringer significantly. Lay out and cut a single stringer and test-fit it against the deck. If it checks out, use it as a tracing pattern for the other stringers you'll need. The first illustration shows an excellent way to support the stair stringers where they're joined to the deck and where they rest on the ground. A notch cut in the bottom edge of each stringer accommodates a 2 x 4 ledger face-nailed to the edge of the deck. The top of the stringers are also nailed to this ledger and to the deck with spikes driven in through pre-drilled holes in the stringer.
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