Most building codes require deck railings to be between 36 inches (91 cm) and 42 inches (110 cm) high. The posts’ extra height above the railing is just for looks. An inch or two higher than the railing will look nice. You’ll need enough length hanging below the surface of the deck to attach the posts securely to the supports. For instance, if your deck is made of boards that are 1 inch (2. 5 cm) thick and the supports are 6 inches (15 cm) high, then you’ll want your posts to be long enough to hang up to 7 inches (18 cm) but at least 4 inches (10 cm) below the railing Many people like to leave about 1. 5 inches (3. 8 cm) or so between the bottom railing and the deck boards as well, so factor this into the post height as well.
If you will use lag bolts, use two 1⁄2 in (1. 3 cm)-diameter galvanized lag bolts with waters and nuts. Washers are used only on the ends of the bolts with the nuts. Drill 1⁄2 in (1. 3 cm) holes through the post and the board behind it. If the posts will be higher than the railing (the railings will not be nailed to the tops of the posts), nail a metal or wooden post cap onto the top of the railing. This prevents water from entering at the top. [5] X Expert Source Walter BrantHandyman Expert Interview. 2 September 2020.
For instance, if you want a railing that is about 36 inches (91 cm) high, make marks on the posts at 40 inches (100 cm). That will leave enough room for the balusters, the top and bottom of the rail, and a couple inches open at the bottom.
Ask your helper to hold one end of the tape measure in place against the center of a post. Stretch the tape measure tightly across to the center of the next post and make a mark. Record the distance between the posts. Check the distance where you want the top and bottom rails to sit. If your posts are straight, the distance should be the same. If they’re not, change the length of the rails to match the actual distance.
Cut 1x3 or 2x4 lumber into lengths equal to the distance between your deck posts. You’ll need two pieces for each length of railing (one for the bottom and another for the top). Get plenty of 2x2 balusters to use for the railing. You’ll want to space these no more than 4 inches (10 cm) apart. The length of the balusters should be approximately the height you want the railing to be. If they’re too long, cut them down. You’ll also need thin strips of wood. Get something that is about 0. 25 inches (0. 64 cm) by 1. 5 inches (3. 8 cm). Cut it into lengths equal to the distance between the deck posts. You’ll need one strip per section.
Really push the paint or caulk into place, because you want it to fill all of the pores. [9] X Expert Source Walter BrantHandyman Expert Interview. 2 September 2020. Make sure you’ve finished cutting, sanding and drilling everything before you apply a finish. Let the finish dry completely before assembly to avoid smudges.
Screws that are 1. 5 inches (3. 8 cm) to 2 inches (5. 1 cm) should be fine.
For instance, you could spread your balusters every 3 inches (7. 6 cm) along the strip, then screw them in. If measuring out the place for each baluster seems too tedious, take advantage of an online deck railing calculator to do the hard work for you.
Screws that are 3 inches (7. 6 cm) to 4 inches (10 cm) long should be fine.
