Fireplace Attic Chase

Seldom do we think about the fireplace metal vent pipe running up through the attic and roof.

Fireplace attic chase.

They are installed to stop a fire in the chase area where the vent pipe runs through to get to the roof. After you know where the penetration point will be for both attic and roof add 2 to all sides. Any wood that is too close to the chimney will undergo a process called pyrolysis and even catch fire at temperatures as low as 200 degrees. We find leaks here especially where the top is framed and enclosed flat and the top flashing lacks adequate pitch and stiffness to avoid collapsing even becoming concave where there are snow loads.

Climb into your attic and locate where your chimney system will enter this space. The base of the chase must accommodate the framing dimensions of your fireplace. Inspecting the firebox clearances is more challenging. We also recommend to insulate the ceiling of the chase just as if it were in the attic space.

My builder is saying that there is no requirement for a firestop since the chase and pipes are on the outside of the house with no floor or attic floor penetration. The manufacturors recommendation is 1 from the fp and 2 from the chimney to combustable materials. Fire stops are self describing. A chimney installer indicated that i would need a firestop in this chase between the first second floor and another one 8 feet up from that.

Measure the height of the furthest point of the installation. Doing this leaves room to encircle the chimney pipe. As currently designed the distance inside the chase to the chimney or firebox will be more like 24 on average with the closest spot about 6. If this height exceeds 15 you are okay to install a attic insulation shield.

If the climate in your area is very cold insulate the chase to the top to keep the chimney warmer increase the draft and reduce creosote buildup. However a home inspector may tell you that there is no fire stop or that it is installed wrong. The chimney chase top chimney chase cover is usually metal constructed of formed aluminum or stainless steel. The rsf manual in the section about chases though they mean outer wall chases says.

Most of the units inspected by chimney professionals are improperly installed and a trip to the attic to check clearances is definitely time well spent.