Stairs/Handrails Skill Level: Expert (Level 3) · Estimated Time: 4-6 Hours

Before You Begin #

Prerequisites #

• Garage floor poured and cured
• Door rough opening set and framed
• Total rise measurement taken from garage floor to top of finished floor inside the house (measure at the threshold location)

What You Need To Know #

When you build garage steps for any residential project, IRC (International Residential Code) requirements govern the entire process. Maximum riser height (the vertical board on each step) is 7-3/4″. Minimum tread depth (the flat part you step on) is 10″. The maximum variance between any two risers is 3/8″. The landing must be at least 36″ in the direction of travel. And guardrails are required if the total fall height (the full vertical drop from top to bottom) exceeds 30″.

Calculate the number of risers by dividing total rise by your target riser height. For example, if total rise is 32″ and you try 4 risers: 32 ÷ 4 = 8″ each - that exceeds the 7-3/4″ maximum, so it fails code.

Try 5 risers: 32 ÷ 5 = 6.4″ each - that works and is comfortable. Then treads equal risers minus one, because the landing counts as the tread for the top step.

Tools Required #

Power Tools #

• Circular saw
• Miter saw
• Drill/driver
• Framing nailer (optional but significantly faster)

Hand Tools #

• Tape measure (25-foot minimum)
• Framing square with stair gauges
• Pencil
• Speed square
• Level (4-foot)
• Chalk line
• Pry bar

Supplies #

• 16d nails or 3″ structural screws
• 2-1/2″ screws (for decking the landing and treads)
• Construction adhesive
• Concrete anchor bolts or Tapcon screws (for anchoring to garage floor)
• Carriage bolts (for stringer-to-landing connection)

Materials #

• 2×12 lumber (for stringers, the diagonal boards that the treads and risers attach to - typically need 2-3 depending on stair width)
• 2×10 or 2×8 (for landing frame joists)
• 3/4″ plywood (for landing deck and tread material)
• 2×4 or 2×6 (for kicker boards and blocking - short framing pieces used for extra support)
• Pressure-treated lumber (for bottom plates and any wood in contact with concrete)

Build Garage Steps with a Landing: Complete Process #

Step 1: Calculate the Layout to Build Garage Steps #

Measure the total rise from the garage floor to the finished floor height at the threshold. This is the most important measurement when you build garage steps with a landing - if it’s wrong, every riser will be wrong. Measure at least twice, ideally three times.

Divide total rise by your target riser height to determine the number of risers. Then calculate the exact riser height: total rise divided by number of risers. Determine the landing height by subtracting one riser height from the threshold height - the landing sits one step down from the house floor.

Pro Tip: Use a story pole. This physical reference catches measurement errors that math alone might miss, especially where precision matters for safe construction. Stand the pole on the garage floor, mark the threshold height, then divide and mark each riser on the pole. You can hold this against your stringers during layout to verify the cuts.

Step 2: Build the Landing Frame #

Building the landing frame is the first major structural step. Build a 2x frame platform at the calculated landing height, using 2×8 or 2×10 joists spaced 16″ on center. The landing attaches to the wall framing on the house side with lag screws (large, heavy-duty screws) or structural screws into the studs, and it’s supported by legs or posts on the garage side. Make the landing at least 36″ deep in the direction of travel (42″ is better), and as wide as the door opening plus any trim. Use pressure-treated lumber for any piece that touches the concrete floor - regular lumber will soak up moisture and rot. Get this framing right, because it needs to last decades without failing.

Step 3: Deck the Landing #

After framing, the next phase is decking the landing. Install 3/4″ plywood on top of the landing frame, and screw it down with 2-1/2″ screws every 8″ along each joist. The landing surface must be level in both directions, and at the correct height - one riser down from the threshold. Check for level across the full surface before moving on. Once the stringers are attached, fixing the landing height becomes much harder.

Pro Tip: The landing height must account for the finished tread material. If the plan calls for adding carpet, tile, or hardwood later, subtract that thickness from the platform height now. A 3/4″ thick finished floor material means building the landing 3/4″ lower than your calculated height.

Step 4: Lay Out the Stringers #

Proper stringer layout is critical to a solid set of steps. Using a framing square with stair gauges clamped at your riser height and tread depth, lay out the stair pattern on the 2×12. Set one gauge at the riser dimension on the tongue, the short side of the square, and the other at the tread dimension on the blade, the long side. Walk the square down the board, marking each tread and riser cut line.

Remember to subtract one tread thickness from the bottom riser height, so that all the finished risers end up equal. The bottom step sits on the garage floor, which acts as its tread surface. That means it needs to be shorter than the other risers, by the thickness of the tread material used on the upper steps.

Step 5: Cut the Stringers #

Cutting the stringers accurately is essential - get this wrong and every step will be wobbly or uneven. Cut along your layout lines with a circular saw. The circular saw blade is round, so it can’t reach the full depth of the inside corners, where the tread and riser cuts meet. Finish these inside corners with a handsaw or reciprocating saw.

Cut your first stringer carefully, test-fit it in place, and verify the riser heights and tread depths before cutting the remaining stringers. Then cut all stringers and verify they match by stacking them together - any deviation means a wobbly step.

Pro Tip: Never cut past your layout lines at the inside corners. Overcutting weakens the stringer at its most critical stress point, because the remaining wood at each notch is what carries the load. Use a handsaw or reciprocating saw to finish the corner cuts cleanly, stopping exactly at the intersection of the lines.

Step 6: Install Stringers to Build Garage Steps #

This connection ties the stairs into the landing platform. Attach the top of each stringer to the landing frame. The preferred method is metal stringer hangers fastened to the landing rim joist (the outer framing board at the edge of the landing). You can also direct-fasten through the rim joist into the end grain of the stringer (the cut end of the board, where screws don’t hold as strongly) with structural screws or carriage bolts.

Set the bottom of each stringer on a pressure-treated kicker plate (a treated board anchored to the floor that keeps the stairs from sliding), sitting on the garage floor. Anchor the kicker plate to the concrete with Tapcon screws - this keeps the stairs from sliding out at the bottom. Use a minimum of 2 stringers for stairs under 36″ wide, and 3 stringers for anything wider.

Step 7: Install Treads and Risers #

Once the stringers are set, the final phase is installing the treads and risers. Install riser boards first if you’re using enclosed (boxed) stringers, then install the tread material on top. Treads should overhang the riser face by 3/4″ to 1-1/4″. This overhang is called the nosing projection, and it’s required by code for stairs with solid risers.

Use both construction adhesive and screws on every tread and riser: glue prevents squeaks, and screws provide the mechanical hold. Pre-drill near the edges to prevent splitting, and drive screws into the stringer at each tread support point.

Step 8: Anchor and Final Details #

The final step is anchoring every connection solidly. Check the entire assembly at every connection point: landing to wall framing, stringers to landing rim joist, and kicker plate to concrete floor.

Check all risers with a tape measure for consistency - the maximum allowable variance between the tallest and shortest riser is 3/8″ per code. Install any required handrails at this stage (if total fall height exceeds 30″, a handrail is required - see the separate handrail mounting guide for details).

Pro Tip: Walk the stairs multiple times before calling the project done. Your feet will tell you if a riser is off - an uneven step feels wrong immediately, even if the difference is only 1/4″. Walk up, walk down, walk normally, walk quickly. If anything feels off, measure and fix it now, not after the trim goes on.

Quality Check: Build Garage Steps with a Landing Correctly #

• All risers within 3/8″ of each other (measure every one)
• Landing level in both directions
• Landing properly attached to wall framing with structural fasteners
• Stringers solid, with no movement or racking (side-to-side shifting)
• Treads don’t flex or squeak under foot traffic
• Nosing projection consistent on all treads (3/4″ to 1-1/4″)
• Bottom of stringers anchored to concrete floor via kicker plate
• Required handrail installed (if total fall exceeds 30″)
• Overall assembly feels solid and stable when walked

Troubleshooting Common Garage Steps Problems #

One Step Feels Higher or Lower Than the Others #

This is the most common issue with garage steps. Re-measure all risers from finished tread surface to finished tread surface. The most common cause is the bottom riser not being adjusted for tread thickness. The bottom step sits on the concrete floor (no tread material added), so the stringer must be cut shorter at the bottom by exactly one tread thickness. Add or remove material at the kicker plate to fix it.

Landing Not Level #

Either the joists are not properly shimmed (packed with thin wood wedges to level them), or the wall attachment point is at the wrong height. Check level across multiple points on the landing surface. Shim under the joists at the low spots, or re-attach the ledger board (the board fastened to the wall that the landing frame hangs from) at the correct height. The landing must be level in both directions - side to side, and front to back.

Stringers Flexing or Bouncing #

If the stringers flex when you walk on them, the stairs need reinforcement. Either you need more stringers, or the existing ones are undersized. Add a center stringer between the outside stringers to get rid of the flex. Always use 2×12 stock for stringers. 2×10 is too narrow for most stair layouts, and it doesn’t leave enough wood above the notch cuts to carry the load safely.

Stairs Pulling Away from Landing #

The stringer-to-landing connection isn’t strong enough. Add metal stringer hangers if you haven’t already. They give a strong mechanical connection that resists both vertical load (weight pressing down) and horizontal pull-out (the stairs sliding away). You can also add structural screws or carriage bolts through the landing rim joist into the stringer tops.

Squeaky Treads #

Screws are backing out or no construction adhesive was used during installation. Remove the treads one at a time, apply a bead of construction adhesive along each stringer contact point, re-set the tread, and re-screw with new screws in slightly offset holes. The adhesive fills micro-gaps that cause wood-on-wood squeaking.

Bottom of Stringers Sliding on Concrete #

The kicker plate is not anchored to the concrete. Drill through the pressure-treated kicker plate into the concrete and install Tapcon concrete screws - at least two per stringer. Clean the concrete dust from the holes before driving the Tapcons. If the kicker plate is missing entirely, add one: a pressure-treated 2×4 or 2×6 fastened to the floor that the stringers bear against.

Helpful Resources #

These external resources provide more detail on stair construction codes, techniques, and safety.

• Family Handyman: How to Build Stairs - Comprehensive DIY stair building guide with detailed illustrations
• This Old House: Building Stairs - Professional stair construction methods and best practices
• IRC Stairway Code Requirements - Official International Residential Code specifications for stair construction

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Reference Photos #

The following photos show examples of this type of work completed in the field. These serve as visual references for quality standards, proper installation techniques, and finished results.

Showing 5 of 5 photos

Basement stairs with open risers and wooden treads mid-construction, drywall walls not yet finished.

Stair construction in progress with raw wood treads, risers, and white-painted skirt boards; layout marks visible.

Raw wood stair treads and risers installed with white-painted skirt board, ready for finishing.

Notched skirt board installed on curved staircase with raw wood treads, ready for paint.

Finished wood risers installed on staircase with painted drywall walls, ready for paint or stain.

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