Porch Railings Calculations Made Easier

Porch Railings Calculations

First, determine how many balusters you will need.

• Add the width of one baluster to the maximum gap that is allowed (usually 4 inches). So, if your baluster is a 2 x 2, you'd add 1.5 inches to 4 inches to get 5.5 inches. (NOTE: Say what? You probably think the width of a 2x2 should be 2" - not 1.5". But remember, lumber measurements are based on the size of the board before it is cut so a 2x2 is actually 1.5 x 1.5 inches.)
• Measure the distance between the two posts (let's say 68.5 inches - the max distance between posts - refer to diagram below) and divide it by the number you calculated above. So 68.5 divided by 5.5 = 12.45
• Round up this number. So 12.45 rounded up = 13. This is the number of balusters you will need between the two posts. (How many spaces will there be? 14 spaces as there is always one more space than total number of balusters).

Now that you know you need 13 balusters (and have 14 spaces), it's time to figure the spacing distance between balusters.

To compute the spacing distance between balusters:

• Measure the width of a baluster. A 2x2 is 1.5 inches.
• Multiply 1.5 inches times the number of balusters. 1.5 inches x 13 = 19.5 inches
• Subtract that from the distance between the posts: 68.5 inches - 19.5 inches = 49
• Divide that by the total number of spaces. So that means 49 divided by 14 (there is always one more space than the total number of balusters). The answer is 3.5.
• So now you know that the space between your balusters will be 3.5 inches.
• Make a spacer that 3.5 inches wide. I like to use a scrap piece of 2x4. Tip: I always make at least two and sometimes four spacers. Why? I use one for the bottom and one for the top. I also am always dropping them. Your spacer should never be greater than the maximum allowed size (in this case, 4 inches)
• There you have it! Like I stated earlier, it's actually easier to do than explain porch railings calculations.