Stainless steel chimney liner installation in Meridian Park

Masonry repairs that must come first

A liner hangs inside the chimney, so the chimney has to be structurally sound. One maker's instructions say that where masonry or mortar joints are missing, loose or cracked, repairs must be made before the liner is installed.

We list that masonry work separately and in order, so you can see what has to happen first, why it has to happen and what it involves on its own line. Some repairs can be done on the same visit as the relining, and others need time before the liner goes in. The estimate says which.

Three situations where insulation helps

One manufacturer lists three situations where an approved insulation wrap enhances the performance and life of the chimney. We explain which, if any, apply to your chimney before you decide, and whether insulation in your case is a requirement or a recommendation.

Insulation also changes the space the liner needs, so the decision comes before the route is proven, not after.

• An installation that must meet UL 1777 at zero clearance to combustibles
• A chimney located on the outside of the house
• Appliances expected to produce low flue gas temperatures

Sizing a liner for an open fireplace

An open fireplace is sized by its opening. Option 1 of section R1003.15.1 calls for a round flue of at least one-twelfth of the fireplace opening area, a square flue of at least one-tenth, and a rectangular flue with a ratio of 2 to 1 or more of at least one-eighth.

We measure the opening, apply the rule that fits the proposed liner shape and write the numbers down for you. A liner that is too small for a large opening can leave smoke at the front of the fireplace, so the opening size decides the liner as much as the chimney does.

What a relining estimate should list

Our written relining estimates list each part of the job, so you can compare them fairly with any other proposal. If a line is missing from a quote you received elsewhere, it is worth asking whether that part was left out or simply not written down.

• The liner product, diameter and length
• Insulation, and whether it is required or optional
• Top plate, liner cap and any extension
• The tee, adapter or other base connection
• Cleaning, tile removal and other preparation
• Separate lines for crown or masonry repairs