Figuring out the Square Footage Determining Square Footage (SF) is pretty simple; it’s a series of multiplication problems.  Most decks can be broken up into a succession of squares and/or rectangles, one for the main deck, one for the landing, and one for the stairs.  Clearly there are many variations, but with a little imagination and vision, and a stroll down memory lane to your geometry lessons in junior high, you can figure it out.

How many steps will my deck have?  This can vary a bit, but I’m going to give you an equation that will answer that question simply and precisely.  Grab a tape measure and measure the height from the ground to where the top of the deck will be.  Take the distance you just measured, in inches, and divide that number by 7.  Round up or down as your math teacher taught you, and that is how many steps your deck will have.  This number, multiplied by 4, will tell you how much SF you have in your stairs (assuming the stairs will be built 4’ wide).

Calculating Number of Steps

As far as SF goes, the hard part is over.  You’ve got your SF number for the stairs, now do the math for the landing SF, and the main deck SF.  Add these numbers together and you have your total SF.

Now it’s time to calculate the railing LF.  Add the dimensions of the perimeter of the deck.  Don’t include the side of the deck that attaches to the house; you’re not going to have rail there.  (I’m not trying to be a smart-ass; I’m just trying to be clear).  For calculating the stair rail, use the following rule of thumb:  for every stair tread (step), there are two LF of rail (one on each side of the stairs).  This is a simple method that works for estimating purposes.

Flat Rail Lineal Footage

Start with your total rise, or, the distance from the ground (where the stairs will land) to the top of the deck surface.  This is A.  Next, determine your total run, or, the distance, on a horizontal plane, from the first step to the last.  This is B.  A squared plus B squared equals C squared.  For the non-math-wizards, grab a calculator and find the square root of A squared plus B squared.  This is the hypotenuse, or the actual dimension of the stair rail.

At this point, you’ve probably acquired enough information that you may be ready to meet with us.  Remember, expert deck design is what we do at Great Railing, so leave those details to us.  Together, we’ll get you where you want to be.