Dome Staircase Build Manual

Novice-Friendly Master Guide

Dome Staircase Blueprint

Modern Timber-Frame · 135° Turn · Uncut Stringer Method

Site Prep Checklist (Do this first)

Remove glass from wall sconce. You will be swinging 17-foot heavy boards around. Don't risk shattering it.
Verify 32" clearance. Confirm the space between the painted brick wall and the utility closet is exactly 32 inches or wider.
Relocate portable A/C unit. The top of the stairs needs a totally clear landing pad on the loft edge.

1 Carpentry 101: Terms & Tech

Don't know builder jargon? No problem. Read this section before making any cuts to understand exactly how a staircase works.

The "Stringer"

The long, heavy diagonal side boards that act as the structural walls of your stairs. You are using an "Uncut Stringer Method". Instead of cutting jagged teeth into the wood (which is hard and weakens the board), you will leave the board straight and mount the steps between them.

"Rise" and "Run"

Rise is how high each step goes up (Vertical). Yours is exactly 7.46 inches. Run is how deep the step is where you place your foot (Horizontal). Yours is 10 inches. If these numbers change from step to step, people will trip. Accuracy is safety.

"Cleats"

Short pieces of 2x4 wood blocks. Because we aren't cutting teeth into the stringers, you will screw these cleats horizontally to the inside of the stringers. Your steps will sit directly on top of these blocks like little shelves.

Plumb Cut vs. Level Cut

A Plumb Cut means cutting a line that goes straight up and down (vertical), like the cut at the top of your stairs that leans against the loft. A Level Cut means cutting a line that is perfectly flat with the ground, like the cut at the bottom of the stairs sitting on the concrete.

The "Lumber Lie" (Crucial Novice Tip)

When you buy a "2x12" board at the store, it is NOT 2 inches thick and 12 inches wide. Wood shrinks when dried and planed at the mill. A 2x12 actually measures 1.5 inches thick by 11.25 inches wide. A "2x4" actually measures 1.5 inches by 3.5 inches. Keep this in mind! Every time you read "2x12" in this manual, know that the wood is physically 1.5 inches thick.

3 Master Cut List

⚠️ Measure Twice, Cut Once!

Do NOT pre-cut all your 17-foot boards into 10' pieces first. The main diagonal stringers require 116.9 inches (9 feet, 8.9 inches). If you pre-cut your boards to exactly 10 feet, you will only leave yourself 3 inches of room to make your angled cuts, which is incredibly difficult for a beginner. Cut the two long stringers first.

Source Board	Primary Cuts (Measure Here)	What to do with the Scrap
17' Board #1	Cut (1) piece exactly 116.9" diagonally. (This is the Top Left Stringer)	The huge piece left over is cut into (2) 32" Treads.
17' Board #2	Cut (1) piece exactly 116.9" diagonally. (This is the Top Right Stringer)	The huge piece left over is cut into (2) 32" Treads.
17' Board #3	Cut (5) pieces exactly 32" long.	These are all treads (steps). Very little scrap left over.
17' Board #4	(2) pieces 32" Treads (2) pieces 32" Landing Floor (2) pieces 34.5" Bottom Flight Stringers	Use the remaining scrap chunks to build the square frame under the landing.
The 2x4 Boards	(22) pieces exactly 10" long.	These are the cleats. No tricky angles, just chop them straight across.
The 4x4 Post	(4) pieces exactly 20.88" long. (20 and 7/8ths inches)	These are the strong legs that will hold up the landing platform.

4 The Five-Sided Corner Landing

Instead of a boring square landing, you are building a custom shape with one "clipped" corner at a 45-degree angle. This is what allows you to turn the stairs outward into the room smoothly.

                  <- - - - - - 54" - - - - - ->
      WALL CORNER _____________________________  
                  |                           |
                  |                           |
                  |                           | <- 32" Wall (Top Stairs attach here)
                  |                           |
                  |_________________          |
                  \                 |         |
                   \ Angled Cut     |         |
     (Exit To Room) \ (45-degrees)  |_________| 
                     \______________|
                        22" Front

How to build this box:

Use your scrap 2x12 pieces to build the outer walls of this shape on the floor.
Screw your four 20.88" 4x4 legs into the inside corners of the box.
Flip it right-side up, and slide it into the corner of your room.
Check it with your level! If the floor is uneven, put wood shims under the legs until the bubble is perfectly in the center.
CRITICAL HEIGHT: The very top of the wood surface, once you put the flat 2x12 top pieces on, must measure exactly 22.38" (22 and 3/8ths) off the concrete.

5 Assembly Step-by-Step

Phase 1: Draw Layout Lines (The Grid)

Lay your two cut 116.9" stringers flat on the floor, facing each other like a mirror.

How to use your square:

Find the 7.46" mark on one side of your framing square (this is your Rise), and the 10" mark on the other side (this is your Run). Lay the square on the board so both of those marks touch the edge of the wood at the same time. Draw lines along the metal edges. Repeat this all the way down.

These lines represent exactly where the steps will sit. They must be perfect. Take your time.

⚠️ The Crucial "Drop the Stringer" Cut

Do not skip this. Go to the very bottom line of your stringer (the level line that will rest on the floor/landing). Measure exactly 1.5 inches UP from that bottom line, draw a new parallel line, and cut it off with your saw.

Why? Because your step boards are 1.5" thick! If you don't cut the bottom off the stringer to account for the thickness of the step, your very first step will be 1.5 inches too tall, and you will trip every single time you walk up the stairs.

Phase 2: Attach the Cleats (On the Floor)

Because the left stringer sits flush against the painted brick wall, you won't fit a drill between the stringer and the wall once it's standing up.

The Pre-Assembly Trick

While the stringers are still flat on the floor in the open room, grab your 10" 2x4 blocks. Apply a zigzag of construction adhesive to the back of the block, line it up directly underneath the horizontal pencil line you drew, and screw it in with three 3" structural screws. Do this for every single step.

Phase 3: Stand Up the Framework

Get a friend. 17-foot 2x12s are heavy and act like giant sails. Do not do this alone.

The Landing: Ensure your 5-sided landing is perfectly leveled and screwed into the wall studs.
The Left Wall Stringer: Stand up the left stringer against the painted brick wall. Secure the top to the loft. Then, use your structural screws to screw directly through the 2x12 stringer, through the drywall/brick, and deep into the wall studs. This makes the stairs bulletproof.
The Right Stringer: Stand it up and secure it to the loft and the landing.
The Bottom Flight: Mount the two short 34.5" stringers from the angled face of the landing down to the concrete floor.

Phase 4: Slide in the Steps (Treads)

Now for the rewarding part. Apply a thick line of construction adhesive to the tops of all the 2x4 cleats you installed.

Slide your 32" step boards into place so they sit on the glue.

Right Side (The Open Side)

Since this side is open to the room, simply drive two structural screws straight through the outside of the stringer, sinking them deep into the end of the step board.

Left Side (The Wall Side Trick)

Since the brick wall blocks you from screwing from the outside, you will secure the step from underneath. Drive two structural screws upward, starting from the bottom of the 2x4 cleat and shooting up into the bottom of the step.

Staircase