The importance of deck railing posts is quite simple. The posts are what support the railings, which in turn prevents people from inadvertently falling off the deck. Poorly spaced posts can weaken the handrail, creating a hazard that can cause serious injury and even death. It is essential to have adequate space between the posts of the deck railing to ensure that the deck is safe and secure.
The building code requires that the support posts for the rail structure be no more than 6 feet apart on a platform with 4 × 4 foot deck rail posts and no more than 8 feet apart for platforms with 6 × 6 foot deck rail posts. Poles should not be more than 5.5 feet apart on stairs. The top of the handrail must be at least 34 inches, but no more than 38 inches high. The same height rules apply to stairs, and the inspector measures the distance from the nose of the stair tread to the top of the handrail. Uneven spacing can seem sloppy and unattractive, so it is important to space the posts evenly to achieve an aesthetically pleasing result.
But why is it so important to leave adequate space between railing posts? A deck railing should support up to 200 pounds of pressure from any direction at any point on the post or handrail. Decks 30 inches or more above ground level require a safety railing that is at least 36 inches high. Keep in mind that while you can add a railing to a platform that is less than 30 inches above ground level, that railing must meet these safety requirements. If there is a handrail, people will lean on it, hoping it will hold them up. If you don't space your posts correctly, even a fall from a pair of feet can cause serious injuries. According to the International Building Code, deck railing posts must not be separated by more than 6 feet.
Sometimes local building codes have more stringent regulations, so check with your local building department for spacing requirements between posts. Calculating the space between the railing posts is the first step in the railing installation process. Start by measuring the distance between the posts of the corners of the platform, making sure to measure each side of the platform that will have railings. If you are going to place posts inside the frame, you will need a post in each corner. For decks with railing posts on the outside, you'll need two posts in each corner. You have a couple of options for the corners of the externally mounted posts.
If you want the posts to be close together, mount each post an inch or two from the corner of the frame. Another option is to mount each post 12 to 16 inches away from the corners, with the top rails extending beyond each post to join at the corner. When spacing the inner posts, be sure to measure from the center of each corner post rather than from the corner of the frame to achieve proper spacing. Since most decks are attached to a house, you'll need to consider the corners of the deck that join the deck's ledger. While there are brackets for attaching a railing directly to the building, unless it's structurally impossible with the design of the terrace, use a pole for these corners. Be sure to mount the posts a few inches away from take into account any ledger and provide an adequate cushion between pole and house.
Once you've determined location of each corner post, it's time to take measurements and determine spacing. Measure distance from center of one corner post to center of next corner post. Divide length of each side into equal lengths between five and seven feet, depending on width of your posts. Unless your deck is perfectly square in shape, space between posts of your deck will vary from side to side. For adjacent 20-foot side, you'll need three posts in addition to corner post that it shares with two 12-foot sides.
To achieve even spacing, 20-foot side will have post every 5 feet. Keep in mind that you may have to adjust spacing depending on joists that go from accounting board to joist of tire. A deck railing post cannot be installed at same point where joists intersect as this could weaken structure and create hazard for anyone using terrace or balcony. It's important to remember that while minimum space may be 6 feet, that doesn't mean you start with first post in corner and move six feet out from there. It is essential for homeowners and contractors alike to understand how much space should be left between deck railing posts for safety reasons as well as aesthetic appeal. Properly spaced railings provide both stability and security while also creating an attractive look for your outdoor living space.