How to Repair an Outdoor Pizza Oven

In this video, This Old House Mason Mark McCullough helps a homeowner fix his pizza oven. The oven’s constructor, another mason, built the structure from fieldstone, brick, and concrete, and Mark loves the design. However, the weather hasn’t been kind to the oven, so Mark lends some expertise.

Steps for Repairing an Outdoor Pizza Oven

1. Survey the damage and attempt to find the cause. Many times, the issue is water penetrating around the chimney or flue, freezing, and cracking grout lines or pushing stones loose.
2. Wearing the dust mask, gloves, and eye protection, remove the old chimney (if necessary) by breaking it into small pieces, chipping away any that remain in the top of the oven.
3. Use a grinder with a diamond blade and dust collection attachment to grind the mortar from the damaged joints, going about ¾-inch deep with the blade. Start with the vertical joints and then move to the horizontal joints. If the joints are curved as is often the case with fieldstone ovens, use the sledgehammer and chisel to remove the mortar. Be sure to hook the grinder up to HEPA vac to control dust. Also, clean the joints with water and a masonry brush after grinding.
4. Pour the dry mortar mix into the mixing tub. Add water in small amounts at a time until the mix reaches an oatmeal-like consistency.
5. Use the small pointing trowels to pack mortar into the brick joints. Start with the vertical joints before moving to the horizontal joints. Be sure not to leave any air pockets or gaps. It may be necessary to use different size trowels at different points to ensure there aren’t any empty spaces.
6. For field stone, scoop mortar onto a hawk. Use Margin trowels of different sizes to pack the joints with mortar mix. Mimic the shape and size of the previous pointing to blend the repair in. Go over the wet mortar with a damp sponge to blend the repair in as much as possible and match the rugged look.
7. Finally, place a bed of mortar around the flue’s opening with a masonry trowel. Set the new flue in the bed of mortar and taper the mortar mix away from the flue to promote water shedding. Let the pizza oven cure for 28 days before cooking.

Materials

• Type N mortar mix
• Water

Tools