Chimney Chase Repair Seattle, WA

Chimney chase repair fixes localized damage to the wood-framed box that encloses a factory-built (prefab) fireplace flue: a rotted top plate or cap framing, trim that has pulled away, soft sheathing at a corner, open seams where water gets in, or a few studs that have lost their strength. Most chases that look bad from the ground are not failed structures. They have one or two weak spots that can be cut out, replaced and sealed while the rest of the chase stays in service.

This page is about that middle ground. If the problem is only the metal cap on top, that is chimney chase cover repair or replacement. If the damage is limited to the exterior siding, that is chimney chase siding repair. And if rot has spread through most of the framing and the chase has started to lean or separate from the house, you are into chimney chase rebuild territory. Chase repair is for the structure itself, short of tearing it down.

James Chimney Sweep has served Seattle, Tacoma and the greater Puget Sound for more than 25 years. We are CSIA certified and licensed, bonded and insured in Washington, and we will tell you plainly whether your chase needs a repair or a rebuild before any work starts.

Timing & Safety

Repair or rebuild: where the line is

The repair-versus-rebuild decision comes down to how much sound structure is left to attach new material to. As a working rule:

• Repair makes sense when rot is confined to the top plate, cap framing, one or two corners, or the trim and sheathing, and the chase is still plumb, square and firmly attached to the house.
• Repair is still worth it when the flue, firestop and chase cover are in good shape and the structure just needs the weak sections replaced and sealed.
• A rebuild is the honest answer when rot runs down most of the studs, the chase has begun to lean or pull away from the wall, the base or ledger is compromised, or patching would mean replacing more than roughly half the framing. At that point piecemeal repair costs more over time than doing it once.

If you are not sure which side of the line you are on, that is exactly what the inspection is for. We would rather recommend a smaller repair that works than sell a rebuild you do not need.

Safety considerations

A wood chase surrounds a metal flue that gets hot. The reasons to fix rot promptly go beyond water damage:

• Rotted framing can let the firestop or flue supports shift, reducing the clearance between the hot pipe and combustible wood.
• Soft top framing can let the chase cover sag and pond water, which accelerates rust on the flue pipe itself.
• Water that runs down inside the chase can reach the fireplace unit and the wall cavities of the house.
• NFPA 211 recommends an annual chimney inspection, and a prefab system should be inspected by a qualified technician any time the chase has been opened or repaired.

Please do not climb on the roof or open the chase yourself. The top of a chase is one of the least stable places on a house, and it is not possible to judge rot from a ladder or from a photo. If your fireplace is gas and you ever smell gas, leave the house and call the gas utility or 911; gas lines and valves are only serviced by a qualified technician.

Seattle & Puget Sound conditions

Framed chases fail at the top for one reason in the Puget Sound: months of rain landing on a flat or nearly flat cap with nowhere to go. Any pinhole in the cover, any open trim joint, any gap at the storm collar sends water straight into the top plate, and it stays wet from October to May. Moss takes hold on the shaded side of the chase and holds moisture against the wood. In the foothills and north Snohomish County, freeze-thaw cycles widen those seams a little each winter. Homes near the Sound add salt air that speeds rust on the cover and fasteners. The practical result is that a chase can look fine from the street while the top eight inches are rotten. Catching it at that stage, while the studs are still sound, is the difference between a repair and a rebuild.