Traditional masonry chimneys are built with clay flue tiles. The majority of chimneys in the Twin Cities were built with 7×11 sized flue tiles. Although this size tile made it easy for masons to build the chimney, they are most often too small for the chimney to function as intended. Current day code regulates the size of a flue tile. The reason for the regulation is to ensure that the chimney will draft properly and that the fireplace does not smoke out your home.
When we are called out to sweep and inspect chimneys we often find that the homeowners are having smoke and drafting problems. Most of the time it is because the flue tile is the wrong size. The current day code states that flue tiles need to be at a 10:1 ratio. So what does that mean? Traditional masonry fireplace openings are 32×26 or 832 inches in area. A 7×11 tile is only 77 inches in area which is an 11:1 ratio, more than likely this chimney will smoke. If you add in the fact that we are trying more and more to tighten up homes to make them more energy efficient it is almost a certainty that this fireplace will not draft and end up smoking out the home.
Insurance companies will often ask us to replace the existing clay flue tile liner with another clay flue tile liner. That is easier said than done. In order to replace the flue tiles we need to get them out. That’s not the hard part. There are tools that allow for us to break out clay liner from the top of the chimney. This is the process we follow when we are putting in a stainless steel liner. The challenge is, how do you stack the tiles back in the chimney? The simple answer is you can’t. The only way to properly reinstall clay flue tiles is to take down the chimney. Clay flue tiles need to be sealed with a refractory mortar on all sides. In order to make sure that they are properly sealed. Clay Liners need to be stacked on top of each other one at a time as you are building up the chimney. The overall cost to tear down a perfectly good chimney and rebuild it, is way more expensive then adding a stainless steel liner. Insurance companies will most often go with the stainless steel liner after being shown the difference in cost.