Should I Line My Chimney?


Here is an update to the poster NEHPBA originally produced for your information:

NFPA 12.4.4* Flue Cross-Sectional Area. For residental-type, natural draft solid fuel burning appliances, the flue shall meet the following conditions:

1. The cross sectional area of the fuel shall not be less than the cross-sectional area of the appliance flue collar, unless specified by the appliance manufacturer.

2. The cross-sectional area of the flue of a chimney with no walls exposed to the outside below the roofline shall not be more than three exposed to the outside below the roofline shall not be more than three times the cross sectional area of the appliance flue collar.

3. The cross-sectional area of the flue of a chimney with one or more walls exposed to the outside below the roofline shall not be more than twqo times the cross-sectional area of the appliance flue collar.

Appliance Flue Size

Flue                        Flue in                            Maximum Size                      Maximum Size

                           Square Inch                        Allowed Inside                        Size Allowed

                                                                       Chimney                                  Chimney

4" Round                 12.56"                                 37.68"                                     25.12"

5" Round                 19.63"                                 58.89"                                     39.26"

6" Round                 28.26"                                 84.78"                                     56.52"

7" Round                 38.47"                                115.41"                                    76.94"

8" Round                 50.24"                                150.72"                                   100.84"

Chimney Size (Square Inches)

                      Chimney Size                           Area in Square Inches

                             6" x 6"                                              36"

                             7" x 7"                                              49"

                             8" x 8"                                              64"

                             9" x 9"                                              81"

                           10" x 10"                                           100"

                           11" x 11"                                           121"

                           12" x 12"                                           144"

                             6" x 10"                                            60"

                             7" x 11"                                            77"

                             8" x 12"                                             96"

                             9" x 13"                                            117"

                            10" x 14"                                           140"

                            11" x 15"                                           165" 

                            12" x 16"                                           192"

Calulating Area of a Circle

The area of a circle is equal to pi times the square of the Raduis. Pi is equal to 3.14.

                               pi X R2 = AREA

Example: If a circle has a 16' diameter, half the diameter is 8', which is the radius. The calculation for the area of this circle is:         

                            3.14 X 64 = 201 SQUARE FEET