Replacing a chimney crown

If you spot any water infiltrating through the attic, it may be because you have leaks in the chimney crown. Most of the times, it is better to replace the whole crown, than try and repair the damaged one.

Tools and materials needed

  • Protective goggles
  • Gloves
  • 2×4-inch board
  • 1×6-board
  • Nails
  • Wood screws
  • Electric drill
  • Miter box
  • Brick chisel
  • Hammer
  • Wire brush
  • Saw
  • Screwdriver drill bit
  • Band clamp
  • Bench saw

Remove old mortar

Use a hammer and a chisel to remove the old mortar from the crown.

Sweep off any dust so that the concrete will stick well to the area.

Build a cap frame

Make a cap frame using 2×4 lumber. Cut the board using a bench saw leaving a 15 degree bevel. Hammer it to a 1×6 inch board. Saw the piece into 4 equal pieces and connect them at the corners using nails.

Place the cap frame

Use band clamp to secure the frame on the chimney. Make sure the frame isn’t damaged or wet. Any cracks should be sealed with tape. The heat will not crack the strong concrete made in the frame.

Expansion joint

Place a piece of cardboard around each flue so that the concrete doesn’t stick to the frame. Pour oil on the frame so you can remove it without taking pieces of the concrete with it.

Mix and pour concrete

Make a concrete mixture using dry concrete, water and gravel or crushed rock. Mix the concrete in a wheelbarrow until it reaches the proper consistency. Place the concrete in buckets and take it on the roof. Pour the concrete into the frame and then insert rebar. The rebar should be 2 inches away from one another.Fill the frame with concrete and smooth it with a trowel. Let the concrete dry for 24 hours, remove the frame, caulk the flue joints and waterproof the crown.

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