Chimney flue repair in Orwin Manor

The mortar that belongs between flue tiles

Ordinary masonry mortar is not what the code asks for inside a flue. Section R1003.12 calls for clay flue liners to be laid in medium-duty, water-insoluble refractory mortar conforming to ASTM C199, a material made to handle heat and moisture inside the passage.

Older chimneys were not always built that way, so we check what the joints actually contain and how it has held up. Where we repair joints, the mortar or listed repair product is named in your estimate, together with the sections it goes into.

Repair or reline, how the choice is made

The decision between a local repair and a new liner rests on a handful of findings. We record each one and show you how they point toward one option or the other.

Where the findings are mixed, we say so and give you both options in writing.

• How many sections are damaged, and where
• Whether the tiles are still in line and supported
• Whether damage is visible end to end or only in part
• What the flue serves now and will serve later
• Whether a listed repair system fits the flue's condition

Tiles that have shifted out of line

When a tile slides out of alignment with the one below it, a ledge forms inside the flue. The ledge catches deposits, disturbs the draft and often leaves an open joint on the other side.

Shifted tiles are usually a sign that the lining has lost support somewhere. We look at how far they have moved and whether a local repair is realistic, or whether the displacement points toward relining. Movement of a single tile at the top can sometimes be corrected when that section is reset. Movement lower down, or across several sections, usually cannot be reached without relining or opening the chimney wall.

Working from the top of the chimney

Much flue repair is done from the roof, especially at the top sections. Access depends on roof pitch, height and how the chimney sits on the roof.

We assess access during the inspection and explain what equipment will be used. If solar panels, fragile roofing or plantings are near the work, let us know so we can plan around them. Tall chimneys may need ladder standoffs, roof anchors or staging. We tell you what equipment will be on the property, where it will stand and how the roof surface is protected while we work at the top.