Proper baluster spacing for deck railing

Maintaining the proper baluster spacing on your deck railing system is important for both aesthetics and safety. Most building codes require a maximum space less than 4" between baluster edges. To be safe, I recommend spacing  wood, composite, glass and metal balusters 3.75" apart (edge-to-edge).

Deckorators metal balustersFor aesthetics, keep the on-center baluster spacing approximately the same around the perimeter of the deck.

When marking for baluster placement, start in the middle of the railing section and allow small space fluctuations to fall near the pressure treated wood or composite lumber posts. Note: drill pilot holes before driving screws into rails to help eliminate splitting.

Check out this tool for a quick and simple way to determine how many balusters your deck railing will need.

Also important to note, there needs to be a gap less than 4" between the lowest point of the bottom rail and the composite lumber or treated wood deck surface, although I would recommend a smaller 3" gap, as it looks better.

Check local building codes in your area for specific details.

Comments for Proper baluster spacing for deck railing

Name: Laurie
Time: Monday, April 19, 2010

This one even has a link to a cool calculator you can use! Looks like they need to be no more than 4" apart for safety.

Name: matt gillette
Time: Wednesday, April 11, 2012

I'm looking for the equation to calculate the spacing for rail balusters

Name: Universal Forest Products
Time: Friday, April 13, 2012


Thank you for your inquiry. Most buildings codes require a spacing of less than 4” between each baluster. An equation to calculate this is to take the actual installed length (in inches) of the railing you plan to use and subtract the combined total dimension of the estimated number of balusters you’ll need for your project. Divide that number by the number of spaces between the balusters (this is the total number of balusters plus one). If that number is less than 4” and over 3” then your estimated number of balusters should work for your project. If the number is over 4 then you’ll need to add the proper number of balusters to make the spacing under 4”. Here’s an example using our Deckorators Classic aluminum balusters with a 6’ railing system. A 6’ rail is 72” in length and a Deckorators Classic baluster is ¾” in diameter. I estimate I’ll need 15 of the ¾” balusters to meet proper spacing on a 6’ rail. So the equation is 72” minus 11.25” which equals 60.75”. Divide 60.75” by 16 spaces between balusters (the total estimated number of balusters plus one). This equates to approximately 3.8” of spacing between balusters. So 15 is the proper number of Deckorators Classic aluminum balusters to use for a 72” railing system.

Both Deckorators and Latitudes understand that proper baluster spacing can be difficult to calculate. That’s why our Deckorators CXT railing (, Deckorators Aluminum railing ( and Latitudes Intrepid railing ( come pre-drilled for proper spacing. This not only takes the guesswork out of baluster spacing but it speeds up installation. Pre-drilling rails can be tedious and time consuming. Deckorators also lists the number of balusters required per linear foot on our aluminum and glass installation instructions. For example, Deckorators Classic balusters require 2.5 balusters per linear foot of railing.

Thank you.

Time: Wednesday, July 25, 2012

Thanks for the great info. We are ordering DecKorator products for our deck construction and this is very helpful.

Name: Mag Bianchini
Time: Friday, September 6, 2013

What is the Ontario code requirement for decks/balconies with steel picket spacing with 10 or 12 mm glass sheets in between the pickets?

Name: Chris Fox
Time: Monday, September 9, 2013

Mag, because building codes vary, you will need to check with your local municipality for proper picket/baluster spacing.

Name: Jim Muehlberg
Time: Monday, March 31, 2014

It can be very frustrating to space balusters. Try this trick (Tom Silva from This Old House). Get some elastic band from the fabric supply house. Put 10 or 12 equally spaced marks, less than 4 inches (doesn't matter). Now, pin down the first mark where you want the first baluster edge. Stretch out the elastic until the "Nth" mark is where you want the last baluster. Transfer the elastic marks to the railing - now you have equally spaced balusters! No more trying to find 6 times 3 and 14/32nds! ;)

Leave a comment


Universal Forest Products is the nation's leading manufacturer and distributor of wood and wood-alternative products to the retail building materials, industrial packaging/components, manufactured housing, residential construction and commercial construction & concrete forming markets.