How To Secure A Loose Stair Stringer And Eliminate Squeaky Treads
A common issue in residential properties is a stair stringer that sits several inches away from the adjacent wall. This gap can cause the stair treads to flex and squeak against the skirt board when walked upon. Fixing this issue requires drawing the stringer tight to the wall framing to restore structural stability and eliminate the annoying noise.
Drilling And Fastening The Stringer
The most effective method for securing a loose stringer is to drive a heavy duty fastener through the stringer, through a spacer block, and directly into the wall studs. Start by drilling a pilot hole. Whenever possible, drill at a perfect perpendicular angle to the stringer. If restricted space requires drilling at an angle, always ensure the drill is pointed downward. Because the force of gravity pulls downward when people walk on the staircase, a downward angled fastener provides much better resistance and structural support than one angled upward.
Selecting The Correct Hardware
Heavy duty lag screws are the ideal fastener for this repair. For a total penetration depth of under five inches, a quarter inch diameter lag screw provides adequate strength. However, if the distance requires a longer screw reaching up to eight inches or more, upgrade to a three eighths inch diameter lag screw. The thicker diameter prevents the fastener from snapping off under the high torque required to drive it into the wood. Keep in mind that heavy lag screws often require a socket wrench rather than a standard impact driver to fully seat them into the framing.
Proper Use Of Spacers And Blocking
The fastener must pass through solid material before embedding into the wall stud. If you drill your pilot hole and miss the existing spacer, do not attempt to tighten the stringer over an empty void. Doing so will warp the stringer and compromise the staircase. Instead, insert a new piece of wood blocking to fill the gap perfectly. You can use heavy lumber like a four by four block to bridge the gap without taking away any structural integrity from the wall framing.
Alternative Methods For Exposed Framing
If the back side of the staircase wall is unfinished and exposed, you can opt for an even more robust solution. Drill a hole completely through the stringer, the spacer block, and the wall stud. Insert a heavy duty machine bolt secured on the opposite side with washers and a nut. This creates an incredibly strong, permanent mechanical connection that will prevent any future movement.
Three Key Tips
Drill pilot holes at a downward angle if a perfect ninety degree angle is impossible, allowing the fastener to properly resist the downward force of foot traffic.
Match lag screw diameter to length by using quarter inch lag screws for distances under five inches, and increasing to three eighths inch for longer spans to prevent the steel from shearing.
Never tighten a stringer over an empty gap; always ensure the space between the stringer and the wall stud is completely filled with solid blocking to prevent warping.
Bonus Questions And Answers
While securing a loose stringer is a great corrective measure, understanding the foundational building science behind staircases can help you identify and prevent other common structural issues.
How Many Stringers Are Required For A Standard Residential Staircase?
The International Residential Code dictates that staircases must be designed to carry a minimum live load without excessive deflection. While the code does not explicitly state a mandatory number of stringers, universally accepted best practices and material span ratings require a minimum of three stringers for a standard thirty six inch wide staircase. This spacing places the stringers roughly sixteen inches on center. Using only two stringers on a standard width staircase causes the treads to bow under human weight, which leads to squeaking, cracking, and eventual structural failure.
What Is The Minimum Required Thickness For A Cut Stair Stringer?
When a builder cuts notches into a piece of lumber to create a stair stringer, they remove a significant portion of the wood's structural capacity. According to the International Residential Code, the uncut portion of the stringer, known as the effective depth, must measure a minimum of five inches of solid wood. To achieve this mandatory depth while accommodating standard stair riser heights, carpenters must use lumber that is at least two by twelve inches in nominal size. Using smaller lumber leaves less than five inches of solid wood, resulting in a dangerous, non compliant staircase that is prone to cracking at the corners of the notches.
Can Standard Drywall Screws Be Used To Fasten Stair Components?
Standard drywall screws should never be used for structural connections in a staircase or any other framing application. Building codes require load bearing connections to be made with approved structural fasteners, such as heavy framing nails, structural wood screws, or lag bolts. Drywall screws are extremely brittle and lack the shear strength necessary to handle the dynamic, shifting loads of foot traffic. When subjected to the constant stress of people walking up and down a staircase, drywall screws will easily snap, causing components to loosen, squeak, and ultimately fail.
