Deck railing posts spacing

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Old 07-05-14, 09:57 AM
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Deck railing posts spacing

Hi. Forgive my stupidity. How do I calculate or better yet can someone calculate for me. I need to know the exact spacing between railing posts. I have the corner posts anchored. They are 17' 2" apart inside to inside. I will be using 3 more 4x4 posts in between the 2 corner posts for a total of 5 posts. What is the spacing on center for each post? Also if you could tell me the method of how you figured this that would be cool for future reference. Thanks.
 
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Old 07-05-14, 10:46 AM
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Generally I like to work with center line instead of edge dimensions. That way the size of the post does not matter. So, I'm adding 3 1/2" to your edge to edge 17'2" dimension to make it 17'5 1/2" center to center. (Each of your end posts is a 4x4 which are actually 3 1/2". The center of each is 1 3/4" from the edge. You have two posts so 2 x 1 3/4" equals 3 1/2")

When in doubt draw it out or use your fingers since you've only got five posts. Count the spaces in between which is four. Then divide the overall center to center length 17' 5 1/2" (209 1/2") by four which gives you "52 3/8" center to center between all of your posts.
 
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Old 07-05-14, 11:44 AM
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Your next question is going to be..."How do I evenly space the ballusters in the odd space between posts?".

You can do all the complicated math or you can use Tom Silva's elastic band method (season 10 #1009). Buy a strip of white elastic waistband material about 6ft long, about $5 at a fabric store. Mark it at 2" intervals. Stretch it out and adjust the spacing so it's not over 4" between marks (I think that's the max spacing allowed by code?). Mark your handrails. Done. You either need a helper or you can use a clamp at one end. Instead of marking the whole length you can just make 2 or 3 marks, then install a few ballusters of your choice and then make a spacer block from scraps for use with the rest.
 
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Old 07-05-14, 04:00 PM
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No Gun... that's too easy. We've got to bring out the math most of us forgot 30-40 or 50 years ago. Sometimes I swear I feel like a third grader with a word problem... A train leaves Chicago at noon traveling 50 mph and a train leaves New York at midnight traveling 25 mph... What wine are they serving in the dining car?
 
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Old 07-05-14, 04:10 PM
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Sally Can't Tell Oscar Has A Heap Of Apples (the clean version). Nuke School...1978.

Btw...I use the stupid method for things like the original post. Ok, X distance between posts...divide by 2..thats the centerline for the middle post. Install that. Divide the remaining sides by 2, thats the centerline for the intermediate posts. When I'm hot, tired, and frustrated by all the other issues, simple is better.

Drawing a blueprint it would be a different story, then you have to account for wood dimensions somewhat. And it only works with odd numbers.
 
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Old 07-05-14, 04:50 PM
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You need a total of 5 newel posts between the ends, find center, then divide the half on each side by 3. That will be the center of the other 2 posts for each side.
 
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Old 07-05-14, 07:54 PM
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Really Larry? You need 2 posts in an approx 8 ft run? Is that best practice or code of some sort? I know my deck back in VA had longer runs then that (about 6-7 ft as I remember), with a support block in the center.
 
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Old 07-05-14, 09:16 PM
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DCA 6 allows a maximum post spacing of 6'-0" (center-to-center) for deck railings. The OP wanted to use 5 total posts, or 4 spaces, meaning his post spacing will be considerably less than the maximum allowed. Not a bad idea, actually, as the shorter a typical railing run between posts is, the stouter (and less prone to deflection) the railing will be. Presuming the posts are properly attached to the deck framing, of course.
 
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Old 07-06-14, 04:02 AM
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No, the OP said he wanted the extra posts. I was just giving the easiest way to gain proper spacing.

Oops, I misread the OP. For a total of three additional posts, not five, find center then find center between the center post and end post. Sorry about the confusion. But my way of calculating post placement works
 

Last edited by chandler; 07-06-14 at 04:47 AM.
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