How to Add Stone to an Arched Interior Doorway

Measure the length and height of the area you want to cover, using a tape measure. Multiply the length by the height to get the gross square footage of stones that will be required. Your measurement will not be exact because of the arch, but it will give you an estimate of how many stones you'll need to cover the arched doorway.

Locate the studs in the wall with a stud finder and mark their location with a pencil.

Cover the area of the doorway where you want to add the stone with a single layer of water-resistive barrier. Attach the barrier to the studs you marked, following the manufacturer's instructions, which generally call for wood screws.

Lay out your stones on a work table so that you can easily see the shapes and varieties available for use.

Mix the mortar according to the manufacturer’s instructions. Use a color of mortar that complements the stones you've chosen.

Use a trowel to spread mortar on the water-resistive barrier where you want to put the stones. Apply a layer of between 1/4 inch and 3/4 inch deep to a 5- to 10-foot area at a time. If you apply the mortar to a larger area, it might set before you put the stones in it.

Push each stone into the mortar, starting at the top center and working your way down the arched doorway. You should push firmly enough to push mortar out around the edges of the stone. Repeat until stones cover the entire area. Leave a space of about 1/2 inch between the stones. For tight areas, use a hatchet to break up the stone so that it fits the space.

Remove excess mortar from between the stones with a metal jointing tool, once the mortar has become firm. Drying time depends on the mortar and the temperature. If you get mortar on the face of the stones, let it dry instead of trying to wipe it off.

Clean dried mortar from the face of the stones with a dry bristle brush. The mortar should crumble off.