Planning Your Chimney Pipe & Stove Pipe Installation
The following recommendations are intended as a general guideline to assist in the layout and selection of the chimney components needed for your installation. Always read and follow Installation Instructions before installing your chimney system. Follow local building codes and have your chimney inspected.
To Get Started
Determine the (inner) diameter of your Chimney. This is usually the same size as the flue collar on your appliance. (See Figure 1). Follow manufacturer recommendations whenever applicable. Never use a chimney that is smaller in diameter than the flue size of the appliance it is being connected to. An improperly sized chimney results in poor draft and excessive creosote formation. Download our Chimney Pipe Planning Guide.
Chimney Planning Step 1
Select the type of installation by determining where your chimney will run. Installations will vary. Determine if the installation is a through-the-roof or through-the-wall installation. Do you have a second story, or a cathedral ceiling? A through the wall installation requires additional components (Wall Thimble, Tee w/Cap, Tee Support, and Wall Straps). Install the chimney pipe in the interior of the structure whenever possible. A cold exterior chimney will produce less draft and will generate more creosote. If at all possible, avoid offsets that restrict the natural draft. A straight vertical installation is more efficient. If an offset is required to avoid rafters or other obstructions, please note that elbows greater than 30 degrees are not allowed in the United States, and a maximum of two offsets in a single installation are permitted. At least one elbow strap is required for each offset.
Chimney Planning Step 2
Determine the number of Chimney Pipe lengths required. The chimney must extend at least 3 feet above the highest point where it passes through the roof, and be at least 2 foot higher than any part of the building within a horizontal distance of 10 feet (Figure 2). The termination cap is installed above this point. If the chimney pipe extends more than 5 feet above the roof, an extended roof bracket must be installed to provide stability against wind and snow. When calculating the installed length of your chimney you must subtract for each joint, (see chart below) and include the height requirements as described. This allows for the overlap of tight fitting joints. Download our Chimney Pipe Installation Guide now.
Minimum chimney height, at sea level, of a straight or vertical chimney is 10 feet to 15 feet above the appliance outlet. Higher elevations, or the use of an elbow or a tee, will require approximately 30% to 60% more height to provide for an adequate draft.
|Brand of Pipe||Subtraction Per Joint|
Chimney Planning Step 3
Measure the roof pitch. For example a 6/12 pitch has a vertical rise of 6 inches over a horizontal distance of 12 inches. Select the appropriate flashing.
To calculate your roof pitch use a 12 inch ruler (level) to measure the number in inches (A) from the end of the ruler to the roof (Figure 3). If (A) equals 6 inches then your roof pitch is 6/12.
Chimney Planning Step 4
Offset calculations (for ceiling support installations only). If an offset is required to avoid rafters or other obstructions, measure the horizontal distance required and the vertical height available (Figure 4), refer to the offset charts for the type of pipe you are installing. For interior systems, Class A pipe begins at the support component. For a flat ceiling, you need to measure from the ceiling in the room with the appliance right up through upper floors, eaves, and attic to the roof. For pitched ceilings, your measurement begins at the ceiling and should include any attic space. Please keep in mind that if your chimney passes through a second story, it must be in a framed enclosure. Refer to elbow offsets chart.
Chimney Planning Step 5
Determine the stove pipe lengths, adapters, and other parts as needed. Measure the distance from the floor where the appliance will sit to the chimney opening. The chimney opening could be in the ceiling or in the wall. If the chimney opening is in the wall, measure the distance to the top of the opening and them measure the diameter of the hole from top to bottom. Take the distance from the floor to the chimney opening and subtract the height of your appliance. The remaining number is the length of stovepipe you need. Please keep in mind the clearance to combustibles for the type of stovepipe and appliance that you have chosen. Single wall stovepipe has an 18 inch clearance, while double-wall can reduce the clearance to combustibles to 6 inches. (Required for Manufactured Home installations.) When calculating the installed length of your stovepipe you must subtract for each joint, (see chart below) this allows for the overlap of tight fitting joints. Note: a typical 8 inch, 90 degree elbow is approximately 8 inches high.
|Brand of Pipe||Subtraction Per Joint|