Earthquake-Damaged and Earthquake-Prone Chimney Repair

On February 28, 2001, the magnitude 6.8 Nisqually earthquake shook the Puget Sound region. Afterward, a University of Washington and U.S. Geological Survey team led by Derek Booth catalogued about 60,000 chimneys from Bremerton to Mercer Island. The damage was not spread evenly. It was concentrated in West Seattle, as it had been in the 1965 earthquake, and it followed the line of the Seattle Fault.

The reason chimneys fail is simple. An old brick chimney is a tall, heavy column with no steel in it, standing above a roof that sways in a different rhythm. FEMA's guide to earthquake hazards, E-74, says unreinforced masonry chimneys are extremely vulnerable to earthquake damage and may be damaged even by fairly light shaking. Bricks that fall can break through a roof or land on a walkway, which is why Seattle changed its repair rules after Nisqually.

Signs you need this

• New cracks in the brick or mortar after any noticeable tremor
• The top of the chimney has twisted, shifted or leans
• A gap between the chimney and the house wall or roof
• Brick, mortar or flue tile pieces in the firebox or on the roof
• An old brick chimney standing well above the roof with no bracing

How we do it

1. Free inspectionWe check the chimney above and below the roof for cracks, shifted courses, gaps at the wall and damage to the flue.
2. Explain the ruleIn Seattle we walk you through what Director's Rule 5-2004 says for your chimney's height and the damage found.
3. Price the optionsYou get written prices for each sensible option, from rebuilding the top to replacing or removing the stack.
4. Do the workWe rebuild, reinforce, brace or replace the stack, and check the flue before the fireplace is used again.

What does Seattle's chimney rule require?

After Nisqually, Seattle required damaged chimneys to be reinforced, braced, removed or replaced with a factory-built chimney. Director's Rule 5-2004 applies that policy to every chimney repair. In summary: repairs under $4,000 need no permit but must follow the rule. Work limited to the top 2 feet may be rebuilt as it was. A chimney more than 3 feet above the roof must be supported at two or more points. Work below the top of the smoke chamber means a full rebuild and a permit. Above 12 feet over the roof, an engineer must design it.

The rule dates from 2004, and we have not confirmed whether a newer version has replaced it, so confirm current requirements with Seattle's Department of Construction and Inspections. Outside Seattle, we check what your city requires before work is scheduled.

What are my options, and what do they cost?

Rebuilding the top courses, where most earthquake damage shows, is typically $1,000 to $3,500. A full rebuild above the roofline, in reinforced brick or with bracing, is typically $5,000 to $15,000 or more. If the shaking cracked the flue tiles, a stainless steel liner is typically $1,500 to $5,000.

If you no longer use the fireplace, taking the stack down below the roof is typically $1,000 to $2,500, and FEMA notes that a chimney not in use can be cut down to 1 to 2 feet above the roof. Before any chimney is capped or removed, we check whether it still vents a gas water heater or furnace, a warning Seattle's rule spells out.

Which option is the safest?

FEMA E-74 calls removing the brick and replacing it with a metal flue in a framed enclosure the most reliable fix. Seattle's rule lists the same option, along with reinforced masonry rebuilds and external bracing to the roof framing. Bracing a chimney in place, FEMA notes, needs an engineered design.

The right choice depends on how you use the fireplace, how much the brick look matters to you and how tall the stack is. FEMA also cites Seattle's rule as a model for other cities. We show you photos of your chimney and the price of each option side by side.