Lapped Corner Treads For Deck Stairs: A Durable Alternative To Miters
When building wrap around deck stairs, traditional mitered corners often seem like the default choice. However, an alternative method using lapped corner treads can provide a more resilient and longer lasting finish for exterior applications. This approach avoids the common pitfalls of miters and offers a unique aesthetic for outdoor living spaces.
The Problem With Traditional Mitered Corners
The classic forty five degree miter joint is a staple in carpentry, but it presents significant challenges when used on exterior deck stairs. Wood is a hygroscopic material, meaning it constantly expands and contracts with changes in humidity and temperature.
Over time, this natural movement causes mitered corners to separate, leaving unsightly gaps that trap moisture and debris. While miters may look pristine on the day of installation, the environmental stress placed on outdoor lumber makes maintaining that tight joint nearly impossible.
How Lapped Corner Treads Improve Durability
Instead of cutting two adjoining boards at an angle, the lapped tread method involves running one board completely to the outside edge while the perpendicular board butts directly against its side. This butt joint configuration accommodates the natural expansion and contraction of the wood without exposing a widening gap. You can alternate the overlap on each step, creating a woven appearance, or run all boards consistently in one direction for a uniform look.
Drainage Solutions For Lapped Treads
Water management is critical in any exterior structure. Because lapped treads create a joint that rests directly over the stair stringer or framing, water can potentially pool in these areas. To ensure proper drainage, you can drill small weep holes through the underlying support board. Alternatively, you can cut shallow drainage notches into the framing directly beneath the joint. If you choose to cut notches, avoid filling them with sealant or adhesive, as the primary goal is to allow water and airflow to pass through unhindered.
Conclusion
Choosing lapped corner treads over traditional miters is a practical decision that extends the lifespan of exterior deck stairs. By planning for the natural movement of lumber and implementing smart drainage techniques, you can build a set of wrap around stairs that looks great and withstands the elements for years to come.
Three Key Tips
Avoid mitered corners on exterior wood stairs, as seasonal expansion and contraction will inevitably cause the angled joints to open and trap moisture.
Incorporate proper drainage when using lapped treads by drilling weep holes or cutting small notches into the underlying framing to prevent water accumulation.
Do not apply sealants or adhesives inside drainage notches, as this will block airflow and prevent water from escaping the joint.
Bonus Questions And Answers
Category A: Practical Application And Tools
What Is The Best Type Of Fastener To Use For Exterior Deck Treads?
Once you have decided on your tread layout, selecting the right hardware is essential for a lasting build. The best fasteners for exterior deck treads are heavily galvanized, stainless steel, or specialized polymer coated deck screws. Unlike standard construction nails or drywall screws, which will rust and snap under the structural stress of shifting lumber, deck screws are designed to flex slightly and resist corrosion over time.
Category B: Maintenance And Troubleshooting
How Can You Prevent Rot Where The Stair Stringers Meet The Ground?
Even with a perfectly designed tread layout, the foundation of your stairs must be protected to prevent future decay. To stop moisture from wicking up into the wood, stair stringers should never rest directly on soil or grass. They should be elevated on a concrete landing pad and separated from the concrete using a moisture barrier or a specialized galvanized steel post base. This separation keeps the end grain of the wood dry and significantly extends the life of the entire stair system.
Category D: Code And Safety
What Are The Building Code Requirements For Stair Tread Depth And Riser Height?
Beyond the aesthetic design of the corners, the overall dimensions of your stairs must prioritize user safety. Standard residential building codes generally require a maximum riser height of seven and three quarter inches and a minimum tread depth of ten inches. These specific measurements are strictly enforced to ensure a natural walking stride, reducing the risk of tripping or falling, particularly on exterior stairs exposed to rain or outdoor elements.
