Remove the form and then apply seal to the flue joints with caulk. Drill screws  into the wood pieces at each corner. #2 Cement crown will have an expansion joint. This chimney crown was not properly constructed: too thin, wrong mix (mortar mix that deteriorated), no expansion gap or control joint … This prevents the concrete from cracks when the flue will heat. But, in fact, this part of the chimney provides a vital function in keeping your house dry and your chimney working efficiently to remove smoke from your fireplace or stove. If you see any gaps, use duct tape to seal them before you apply the mortar. This overhang should be at least two inches. But much of the time, chimney crowns are poorly built. The only way to prevent this is to install an expansion joint when building the crown. Chimney Weather Cap - Chimney Crown Construction Details. When building a chimney crown you must follow a few simple steps. Use oil  inside the form surface to avoid it from sticking when stripped. In many situations, it is not even recognized as a part of the chimney. masonry. Set the frame on the chimney brick and reinforce it with a load binder or a band clamp. The chimney "cap" [or crown] should slope away from the flue at a good rate of about 3-inches per foot. When building a chimney crown you must follow a few simple steps. Chimney Repointing & Mortar Joint Repair in the DC Metro Area. As I was cleaning my Chimney liner to prep this season, I noticed my crown is in disrepair. Use small aggregate and mix concrete. Terry Dearborn of Valley Chimney Sweep is the longest continually Certified Chimney Sweep® in the United States. crown •Expansion joint of 3/8” between tile and crown Chimney Crowns •A crown should have the following •2 ½” overhang •Drip edge 1” from the chimney •2” thick at the edge •Expansion joint between brick and crown •Expansion joint 3/8” between tile and crown •Concrete Chimney Crowns It looks to be poorly done and very thin, even without expansion joint around tile flue. From baffles to corbels and parging, the field of chimney repair and maintenance has some interesting terminology. Chimney expansion joint Even if a chimney crown may seem as an insignificant part of the chimney, it helps prevent things like rain or small animals enter the chimney and also helps remove the smoke from the chimney more efficiently. And some crowns reston combustible supports such as plywood or tar paper, which can burn and sag. Chimney crowns are very important to the integrity of your chimney; an improperly installed chimney crown could cost you thousands of dollars in repair work down the road. Waterproof the crown. Differential expansion will cause cracking and water penetration. Water is your chimney's worst enemy, particularly in colder climates. The 2×4 bottom has to be flush with the frame bottom. By installing this material you are ensuring your flue tile has the proper room to expand and contract. Serving Nanaimo, Victoria, Duncan, Vancouver, and Calgary. Meets requirement of ASTM D 1751. A full coverage chimney cap usually represents a larger initial investment. Chimney flue tiles will stick out of the top of the chimney, and each flue tile is supposed to have an expansion joint around it so that the flue tiles can expand when the fireplace or appliances that they are venting heat up without pushing on the crown causing it to crack. Pour water into the mix and then apply 1 inch of concrete into the form. Use 2×4 boards to construct a frame. 6917) are made from resilient wood fibers to prevent damage during expansion and contraction of concrete. Since plywood absorbs water, it also can expand and crack the crown. Poor crown construction is a leading cause of chimney … Remove the form and then apply seal to the flue joints with caulk. Waterproof the crown. However, it is probably the best investment for long-term protection because of its ability to protect the entire chimney crown. With no expansion joint, your flue tile will push against the chimney crown on all sides and something has to give, usually your chimney crown. Create an expansion joint placing corrugated cardboard around each flue and keeping it in place with duct tape. Use oil  inside the form surface to avoid it from sticking when stripped. Whether made of precast or cast-in-place concrete, a properly constructed chimney crown (also called a cap or top plate) sheds water and seals the top of the chimney. An expansion joint is a flexible joint between the flue tiles that extends through the top of the chimney and the crown or wash. As flue tiles heat up and cool down they expand and contract. Don’t get oil on the brick surface or it will not bond to the concrete. This way the concrete won’t crack as the flue heats and then expands. Others, like chimney repointing, aren’t as easy to figure out. 1/2 inch x 4 inches x 5 feet. Using the right materials, following the correct procedure, and consulting with a professional will help you to construct a chimney crown … Brick Chimney Crown A brick chimney crown – also known as a chimney termination cap, cement wash, or just a chimney cap – seals the chimney top opening around the flue and sheds rainwater / prevents moisture from deteriorating the chimney. When crowns are built without an expansion joint, they can crack due to the force of the hot, expanding flue tiles. For the chimney crown to fulfill its purpose, it must be properly shaped and installed. Even if a chimney crown may seem as an insignificant part of the chimney, it helps prevent things like rain or small animals enter the chimney and also helps remove the smoke from the chimney more efficiently. In our photo the red arrow points to the concrete chimney weather cap or chimney crown. QUIKRETE® Expansion Joint Strips (No. Fill the form with concrete and then smooth and tamper it. Spongy insulation is wrapped around the chimney flue when the crown is poured, leaving room for the hot flue tiles to expand. A chimney crown or mortar cap might seem to be a simple and sometimes insignificant part of a chimney. Repair or Replace a Damaged Chimney Crown The chimney crown (also referred to as the chimney wash) is the top element of a masonry chimney. If you see any gaps, use duct tape to seal them before you apply the mortar. The reason for an expansion joint is to prevent the damage caused by constant freezing and thawing. Perhaps most important of all in the prevention of cracks in a chimney crown is an expansion joint. Chimney flue tiles will stick out of the top of the chimney, and each flue tile is to have an expansion joint around it so that the flue tiles expand when the fireplace or appliances they are venting heat up without pushing on the crown causing it to crack. Weather resistant. The "expansion joint" should be sealed with a flexible durable sealant to keep the water out of the chimney. A mortar cap, or chimney crown, that has been improperly constructed, or one that has become deteriorated over time, may be the cause of water leaking into your attic through cracks or broken mortar in the crown.When this happens, it is sometimes better to replace the crown than attempting to repair it. 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