DIY Network

How to Install a Prefab Arch

The Bathroom Renovations team shows how to easily install a prefab arch around a bathtub.

More in Remodeling

  • Time


  • Price Range

    $500 - $1,000

  • Difficulty

    Moderate to Hard


Step 1: Choose a Spot for the Arch

Determine where the arch will be placed. Measure down 8-3/4" for the location of the arch header, taking into account the depth of the drywall. Use a speed square to draw a square line on both sides.

determine where arch will be placed

Step 2: Slide the Arch Into Place

The arch header is a piece of 2x6 cut to length and toenailed to the sidewall (Image 1).

The two pieces of the arch fit together in the middle, and can be adjusted for the size of our opening (Image 2). Dry fit the pieces down low and then slide the arch up into place (Image 3).

Step 3: Secure the Arch to the Studs

Check the distance between the arch and the ceiling, to give proper alignment for the arch.

Compare the two measurements and adjust the arch pieces accordingly, until they're an equal distant from the ceiling. Clamp the arch temporarily in place, then attach it to the studs with 1" screws.

clamp arch temporarily in place

Step 4: Cut the Drywall

Start with a plunge cut into the drywall with the rotary tool. Push the tool to the edge of the arch and follow the line all the way around.

cut into drywall

Step 5: Score and Secure the Drywall

For the final cut, score along the back of the drywall with a utility knife, snap out your piece, then another score on the front to give the cleanest cut possible (Image 1).

To score the drywall, run a speed square along the edge and drag the utility knife across every four inches (Image 2).

After scoring, lift the drywall and form it to the arch. With the proper fit, secure the piece into place (Image 3).

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