Wooden stair stringers are literally the backbone of any staircase. They support all of the weight of the treads and risers, as well as the punishment that we put it through every time we climb up or down the stairs. Since the stringer is so vital, taking extra care to reinforce them when building a new stair is a good idea. This article will outline many of the options you have when looking to reinforce your wood stair stringers.
Step 1- Install Skirt Boards
One of the easiest methods of reinforcing your wood stair stringers is using 2x12 skirt boards along the outsides of your stairs. A skirt board is pretty much what it sounds like; triangular shaped wood that goes along the sides of your stair and hides all of the unsightly notched stringers and hardware. You may not be able to use skirt boards on both sides of your stair, depending on it's placement in your home. This is a great addition to an exterior deck wood stair, as well as interior stairs. This skirt board also provides a solid piece of wood to attach any rails to as well.
Step 2- Brace the Stringers
Another option to strengthen your wood stringers is to brace the center stringer with 2x4s. Just measure the height from the brace point down to the floor and cut the 2x4s accordingly. Attach them to the center stringer using screws or brackets. The center stringer is the one that takes the most abuse, due to us walking in the center of the stair the most often. This is why this bracing is really only necessary for the center stringer, rather than bracing all three.
Step 3- Reinforce with Brackets
You can also reinforce the joints of the stringer with L-brackets. These brackets can help brace the stair together, and will help prevent any squeaking and wobbling. The less unnecessary movement that your stair has the better, it will last longer if it is solid and unmoving. Whether it is the tread or the riser that has become loose, an L-bracket with 3/8-inch wood screws will solve most issues.
Step 4- Maintenance
The last and most important step is maintenance. You should be checking the condition of your stairs every year. Frequent maintenance will help catch a problem when it is still an easy fix. Go ahead and walk along the stairs and hammer down any areas that may be loose. Start down by the kickboard (the 2x4 that anchors the bottom part of the stairs). Also, if you have access to the back of the stairs, you should go ahead and check to make sure that the upper part of the stringers where they attach to the upper floor are still in good shape. This area should be secured with a hanger or ledger board. Make sure that all of the screws are still tight. Using the brackets mentioned in step 3, going over any loose treads will make the structure of the stair stronger. Some builders also reinforce the tread and risers with a triangular notch of wood screwed into the angle where they meet.