How to Install Prefab Wood Stairs


Things You’ll Need

  • Installation manual

  • Level

  • Tape measure

  • T-bevel

  • Saw

  • Stud finder

  • Finishing nailer

  • Finishing nails

  • 2-by-4-inch lumber

Outdoor staircase Some prefab staircases require rudimentary assembly before installation. Image Credit: Hemera Technologies/ Images

Prefabricated staircases come complete from the manufacturer. Purchasing a prefabricated staircase saves you money on carpentry costs, and installation takes less time than installing a handmade staircase. Installing a prefabricated wooden staircase involves only a handful of relatively simple steps and requires a basic set of tools. Keep in mind, however, that you must set up a landing for the top of the staircase before beginning the installation process.

Video of the Day


Step 1

Lay the staircase on its side and measure the length of the unit with a tape measure. Find the midpoint of the staircase and mark it with a pencil.

Step 2

Measure the angle of the staircase using a T-bevel, a gauge that adjusts to inclinations.

Step 3

Line up the prefabricated staircase with an existing landing so the top framing elements of the stairs line up with the edge of the landing. Ask a friend or family member to help you hold the staircase in place.

Step 4

Place a level across the top of the staircase and landing at both sides of the stairs to ensure the staircase is even. If not even, manually adjust the staircase until even.

Step 5

Draw a line on the front of the landing and a line on each side of the staircase while holding the staircase in an even position. Draw lines at the same height.

Step 6

Measure the height from the floor to the midpoint of the staircase as previously marked.

Step 7

Remove the staircase from the landing and place it on the floor.

Step 8

Measure a two-by-four to the height of the midpoint of the staircase. Mark the height with a pencil and cut the two-by-four to length with a saw.

Step 9

Mark an angle equal to that of the staircase on one end of the two-by-four using a T-bevel and pencil. Cut along the angle line, using a saw, to angle the end of the two-by-four.


Step 1

Move the staircase back into place, with the help of an assistant. Check that the lines drawn on the sides of the staircase line up exactly with the lines on the landing.

Step 2

Check the flatness of the transition from the staircase to the landing once more, using the level.

Step 3

Attach the staircase to the landing by driving finishing nails through the top framing element of the staircase and into the landing. Base the number of nails used on instructions provided by the manufacturer of the prefabricated staircase.

Step 4

Place the cut two-by-four underneath the staircase so the flat end sits against the floor and the angled end fits against the staircase. Drive a nail through the two-by-four and into the staircase to provide a temporary support beam.

Step 5

Locate studs in the wall abutting the prefabricated staircase if you're installing stairs against a wall.

Step 6

Drive nails through the side of the staircase into the wall studs to anchor the staircase to the wall.

Step 7

Install any brackets provided by the manufacturer of the staircase. Brackets generally assume the form of L-shaped pieces of metal that install with one side against the staircase and one side against the floor.

Step 8

Complete any finishing touches recommended by the staircase manufacturer, such as applying a varnish or waterproof finish to the surface of the wood.


Upon finishing installation of a prefabricated staircase, you may want to build a wall beneath the stairs to give them a finished look. Install a cleat, or scrap piece of two-by-four, in front of the bottom stair and nail it to the floor to prevent the stairs from slipping during wall installation.

Always follow specific instructions provided by the manufacturer of a prefabricated staircase regarding installation.


Installing a prefabricated staircase requires exacting measurements. Always measure an area for installation before ordering a staircase so you get the right size stairs.

Share this article

Recent posts

Teachers’ Top Needs for 2019

Teachers’ Top Needs for 2019Great classrooms don’t happen by accident. Teachers across the country work hard to build vibrant, energizing learning environments for their students, which often means ev

Top Tips to Transition Back to Work After Baby

Top Tips to Transition Back to Work After BabyMany new parents spend hours preparing for the arrival of a new baby – reading books, seeking professional advice and consulting friends and family. Howev

Get Away Without Going Away

Get Away Without Going Away5 family staycation ideas that won’t break your budgetFamily vacations are a great way to bond and take a step back from the hectic schedules that accompany everyday life, b

5 Common Questions for Memorializing a Loved One

5 Common Questions for Memorializing a Loved OneOne of the most difficult conversations in a person’s life typically takes place near the end of that life. Planning for a funeral can put an emotional

Boat Safe

Boat SafeEnsure your boat is ready for the water with this checklist No matter how much experience you have on the water, prepping your boat – and your passengers – before leaving the dock can make fo


Please enter your comment!
Please enter your name here

Recent comments