If you want to build exterior stairs that stay solid for years, this walkthrough from @AndrewThornImprovements breaks down the entire process from start to finish. He covers everything you need to know while using Power Pro products: calculating stringer cuts, attaching stairs to the deck, building the landing, and finishing the project with clean, professional results. This method is designed to help your stairs last longer and hold up in real outdoor conditions. It's a practical guide for anyone building new stairs or upgrading an existing deck.

Watch the full tutorial: How to Build Exterior Stairs That Last | Andrew Thron Improvements x Power Pro 
Get Andrew's FREE e-book: “How to Build a Deck” [youtube.com] 

Tools & Materials

• Power Pro Structural Lag Screws >
• Power Pro 3" Exterior-Rated Screws >
• Power Pro Concrete Anchors >
• Power Pro Joist Tape >
• Pressure-treated lumber: 2x12 for stringers, 2x6/5/4 for treads, 2x4/2x6 for landing frame
• Concrete mix or pavers for landing/footing, gravel base. framing square, stair gauges, circular saw, drill/driver, level, measuring tape, clamps, PPE
  

Step 1: Plan the Stair Path, Rise, and Run

1. Measure the total rise from finished deck surface to finished grade/landing surface.
2. Select riser height (commonly 7-7 1/2") and divide total rise to determine number of steps.
3. Set tread depth (10-11" typical)  and check total stair run fits your site.
4. Confirm landing size and position (clear, level, and aligned stair path).

Andrew's walkthrough emphasizes getting the math right upfront so your stairs feel natural and pass inspection.

Code reminder: Typical residential guidelines aim for 7-7 1/2" rise and 10-11" run, with risers within 3/8" variation max. Check local codes before you cut.

Step 2: Lay Out and Cut the Stair Stringers

1. Use a framing square with stair gauges to mark the rise/run triangles on 2 x 12.
2. Account for tread thickness at the top and bottom so finished risers are consistent.
3. Cut with a circular saw, then clean inside corners with a handsaw/jigsaw to avoid overcuts that weaken the stringer.
4. Duplicate the layout for the remaining stringers (most 36"-wide stairs need 3 stringers; wider stairs need more-check spacing).

Andrew's approach favors precision and repeatability. Set the first stringer perfectly, then trace it for the others to save time and keep everything identical.

Step 3: Prep Blocking and Deck Attachment

Before mounting stringers, Andrew blocks and reinforces the rim/ledger area so the stair load transfers cleanly into the deck frame:

• Install 2x blocking at the attachment point with Power Pro 3" Exterior-Rated Screws (fast drive, corrosion-resistant).
• Where structural tie-ins are needed, step up to Power Pro Structural Lag Screws for shear and withdrawl strength.

Tip: Pre-drill for lags in dense PT lumber to reduce splitting and achieve full thread engagement.

Step 4: Build a Solid Landing/Base

If your stairs terminate at grade, Andrew shows a landing that won't heave or loosen.

1. Excavate and compact a gravel base (drainage first).
2. Form and pour a concrete pad (or set structural pavers) sized to your stair width.
3. Anchor the landing framing (if framed) using Power Pro Concrete Anchors, this prevents racking and creeping over time. Well anchored landings maintain consistent riser heights season-to-season and feel "tight" underfoot.

Step 5: Set Stringers and Fasten Securely

1. Position stringers so they're plumb and evenly spaced (often ~16-18" on center-wider stairs add stringers).
2. Top attachment: Use Structural Lag Screws through blocking/ledger or install metal stair hangers per local code.
3. Bottom bearing: Ensure full support on the landing; shim only with approved materials-no soil bearing.

Step 6: Moisture Defense with Joist Tape

Before treads go on, Andrew applies Power Pro Joist Tape to high-exposure surfaces (stringer tops, landing framing).

Step 7: Install Treads (and Optional Risers)

1. Pre-cut treads and dry-fit uniform overhang (nosing).
2. Fasten with Power Pro 3" Exterior-Rated Screws
3. Add risers if your design calls for them; keep a clean reveal and square corners.

Pro Tip: Slightly slope treads for drainage to avoide standing water and slipperiness over time.

Step 8: Final Alignment, Trim, and Safety Checks

• Sight down the stair for parallel stringers and uniform nosing.
• Check risers with a tape and square-keep variations under 3/8"
• Add railing/lighting per local code and environment (ice, heavy rain).