How to Build an Outdoor Stone Fireplace

What You'll Need
4 by 4 and 2 by 4 posts
Metal wire lath
Hand trowel
Masonry saw
Fire pit or fireplace unit
Damp cloth

Building an outdoor stone fireplace is a great way to utilize your personal space during the cold winter months. It can be built in your garden, back yard or patio to extend the use of your outdoors, even when it’s chilly.

Step 1 – Seek Permission

Check with your local building department before purchasing materials for an outdoor fireplace. They may need to send someone over to check your area because of the safety issues involved with a fire.

Step 2 – Select a Suitable Location for the Stone Fireplace

Look around your property for a suitable spot to build your fireplace. Make sure the site is on level ground and at a safe distance from your house, garage, fences and other buildings. It should also be clear of any hanging branches or vines, to avoid any fire hazards.

Decide whether you want an outdoor wood-burning fireplace or one that uses charcoal or gas. A gas unit is a good idea if you have gas installed around your house. Simply call a professional to connect the lines to your unit.

Step 3 – Design Your Fireplace

Design a frame for your fireplace, including a chimney, depending on the size of the area and your home's architectural design. The frame should be either a large rectangle or square, since it will include the fire pit or fireplace unit. The exact measurements of the base will depend on the size of the unit you want to install. Ideally, the base should be large enough to hold the fireplace and encourage it to burn. Also check the installation guide of the unit to get an idea of space and airflow requirements needed.

The chimney should be at least 8 to 10 feet high, to expel smoke overhead without irritating people sitting or standing around the fireplace.

Step 4 –Create a Frame

Create your frame with your posts. Use 4 by 4 posts to create vertical supports for your fireplace, and 2 by 4 posts for horizontal supports. Nail them together to get the desired frame. Cover the frame with 5/8-inch plywood and install the fireplace unit.

Step 5 – Secure Frame Using Wire Lath

Nail a metal wire lath to the frame, making sure it is secure. Apply mortar and let it dry before proceeding. 

Step 6 – Apply the Stones

Use your hand trowel to apply mortar to the back of each stone before attaching it to the frame. Try to keep the stones as close to each other as possible. Stack the stones all the way up the frame, including the chimney. You may need to cut some stones into smaller pieces with a masonry saw to make sure they fit tightly. Push mortar in between stones on the fireplace structure where necessary. 

Use a damp cloth over the frame and chimney to remove excess mortar. Apply a layer of grout if the metal wire lath is visible on the edges.

Allow the mortar 36 to 48 hours to dry.