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What does “Parging a Smoke Chamber” mean?

parging fireplace smoke chamberFireplace smoke chambers are a hot topic among homeowners. What exactly is the smoke chamber, you ask? It’s the funnel-shaped section of your fireplace that directs smoke from the firebox and into the flue. Corbelling brick, a method of laying bricks like steps to achieve the desired shape, forms the funnel shape. The method works well for creating the desired shape, however, due to the way it’s done, gaps are common. The NFPA requires smoke chambers to be parge-coated smooth, with an insulating refractory mortar; parging is a means of addressing this issue while at the same time improving the overall efficiency of your chimney system.

WHAT IS PARGING AND WHY SHOULD I CONSIDER IT?

Parging is an economical and easy-to-apply solution for covering unattractive masonry surfaces. When done correctly, parging offers several benefits:

  • Improved safety of the chimney;
  • Increased structural integrity of the smoke chamber area;
  • Improved draft and fireplace performance, which lowers the amount of creosote that builds up within the chimney system.

Most parging mixtures are made from a blend of lime, Portland cement, water and masonry cement. To apply it, mortar is troweled onto the wall and spread over the surface in a thin layer. It can cover cracks and water damage, or even holes and voids. The mortar may also help to seal small air leaks in a concrete wall, which may lead to a slight improvement in energy efficiency.

CAN YOU EXPLAIN THE PARGING PROCESS?

The first step in the parging process involves a thorough cleaning of the area to be covered. Scrubbing with detergent and water using a stiff-bristle brush removes loose mortar, soot and grime, to ensure that the parging will bond well with the wall. The wall is rinsed with water as each section is cleaned. Bricks that have eroded deeply are chiseled out and replaced with new bricks. Each new brick, and the surrounding bricks, are misted with water before buttering the brick with mortar and sliding it into place.

To ready the section of wall to be parged, it is first misted with water. This is an important step, as it keeps the wall from absorbing moisture out of the mortar and causing it to dry too fast. If the mortar were to dry too fast, it would be soft and crumbly. The mortar is then applied using a mason’s trowel by loading it with mortar by turning it over and scooping mortar onto the bottom. A sweeping motion is used to spread the mortar on the wall, moving upward, and applying gentle pressure to force mortar into the various contours of the wall. The finished product is about a quarter-inch thick.

To determine if your smoke chamber needs parging, an annual inspection is key. The CSIA-certified professionals at Chimney Saver Solutions will be able to let you know if your smoke chamber is in need of parging before it becomes a fire hazard. Contact us today to schedule an inspection to assess your smoke chamber’s condition. What are you waiting for? Give us a call!