How to Cap a Chimney
Identify your chimney type., Measure for a square masonry chimney., Measure for a round chimney.
Step-by-Step Guide
-
Step 1: Identify your chimney type.
You'll need to measure the dimensions of your chimney before buying a cap for it, and you'll need to know which type of chimney you have to do so.
Most chimneys can be divided into two basic categories: square masonry chimneys and round chimneys.For square masonry chimneys, you will need to measure the flue—the pipe that carries the flame and smoke outside.
Chimneys with one flue can be capped with a single flue chimney cap, but those with multiple flues will usually need a crown mount cap.
Round chimneys are usually made of metal but could also be made with masonry.
Either way, you will need to measure the diameter of the chimney pipe before installing a round chimney cap. , There are three subcategories to consider: single flue chimneys with extended flues, single flue chimneys without extended flues, and multi-flue chimneys.
The single flue chimney with an extended flue is the most common.
Single flue chimneys with extended flues have a flue that extend beyond the crown of the chimney, making it easy to attach the cap with screws.
Measure the width and length of the flue from the outside of the chimney.
Single flue chimneys without extended flues are flush against the chimney top, so you will need a cap with a bracket that reaches into the flue and grips into the side.
Measure the width and length of the opening itself, not the outer portion of the flue.(Note this illustration is not showing this correctly.
The measurement should start at the inside of the hole.) For a multi-flue chimney, measure the total outside width and length of the combined flues.
You also need to measure the height of the tallest flue.
The cap you choose will need to have a screen height at least 5 inches (12.7 cm) taller than the top of your highest flue. , Most round chimneys are made of metal, but there are two sub-categories you need to concern yourself with: solid-pack insulated chimney pipes and air-insulated chimney pipes.
Note that the measurements you need for the cap will be the same regardless of the pipe type.
Look into the chimney.
You should notice a pipe within a pipe (double-wall) or a pipe within two larger pipes (triple-wall).
If you see a metal cap or insulation packed in between the pipes, you have a solid-pack chimney pipe.
If you see nothing but air, you have an air-insulated pipe.
Measure the diameter of the inner pipe and the diameter of the outer pipe.
The inner diameter should be used when selecting the cap, but the bottom ring of the cap should be large enough to cover the diameter of the larger pipe.
If you have a triple-wall pipe, ignore the middle pipe when taking the measurements. -
Step 2: Measure for a square masonry chimney.
-
Step 3: Measure for a round chimney.
Detailed Guide
You'll need to measure the dimensions of your chimney before buying a cap for it, and you'll need to know which type of chimney you have to do so.
Most chimneys can be divided into two basic categories: square masonry chimneys and round chimneys.For square masonry chimneys, you will need to measure the flue—the pipe that carries the flame and smoke outside.
Chimneys with one flue can be capped with a single flue chimney cap, but those with multiple flues will usually need a crown mount cap.
Round chimneys are usually made of metal but could also be made with masonry.
Either way, you will need to measure the diameter of the chimney pipe before installing a round chimney cap. , There are three subcategories to consider: single flue chimneys with extended flues, single flue chimneys without extended flues, and multi-flue chimneys.
The single flue chimney with an extended flue is the most common.
Single flue chimneys with extended flues have a flue that extend beyond the crown of the chimney, making it easy to attach the cap with screws.
Measure the width and length of the flue from the outside of the chimney.
Single flue chimneys without extended flues are flush against the chimney top, so you will need a cap with a bracket that reaches into the flue and grips into the side.
Measure the width and length of the opening itself, not the outer portion of the flue.(Note this illustration is not showing this correctly.
The measurement should start at the inside of the hole.) For a multi-flue chimney, measure the total outside width and length of the combined flues.
You also need to measure the height of the tallest flue.
The cap you choose will need to have a screen height at least 5 inches (12.7 cm) taller than the top of your highest flue. , Most round chimneys are made of metal, but there are two sub-categories you need to concern yourself with: solid-pack insulated chimney pipes and air-insulated chimney pipes.
Note that the measurements you need for the cap will be the same regardless of the pipe type.
Look into the chimney.
You should notice a pipe within a pipe (double-wall) or a pipe within two larger pipes (triple-wall).
If you see a metal cap or insulation packed in between the pipes, you have a solid-pack chimney pipe.
If you see nothing but air, you have an air-insulated pipe.
Measure the diameter of the inner pipe and the diameter of the outer pipe.
The inner diameter should be used when selecting the cap, but the bottom ring of the cap should be large enough to cover the diameter of the larger pipe.
If you have a triple-wall pipe, ignore the middle pipe when taking the measurements.
About the Author
Samuel Griffin
Writer and educator with a focus on practical crafts knowledge.
Rate This Guide
How helpful was this guide? Click to rate: