Mich. Admin. Code R. 408.30547f - [Rescinded effective 8/29/2025] Systems
Rule 547e.
Sections N1103.2.1, N1103.2.2, and N1103.4.2 of the code are amended to read as follows:
N1103.2.1. Insulation (prescriptive). All
portions of the air distribution system shall be installed in accordance with
Section M1601 and be insulated to an installed R-6 when system components are
located within the building but outside the conditioned space, and R-8 when
located outside to the building thermal envelope. When located within a
building envelope assembly, at least R-8 shall be applied between the duct and
that portion of the assembly farthest from conditioned space.
Exception: Portions of the air distribution system within appliances or equipment.
N1103.2.2. Sealing (mandatory). Ducts, air
handlers, and filter boxes shall be sealed. Joints and seams shall comply with
either the international mechanical code or international residential code, as
applicable.
Exceptions:
1.
Air-impermeable spray foam products may be applied without additional joint
seals.
2. Where a duct connection
is made that is partially inaccessible, 3 screws or rivets shall be equally
spaced on the exposed portion of the joint so as to prevent a hinge
effect.
3. Continuously welded and
locking-type longitudinal joints and seams in ducts operating at static
pressures less than 2 inches (51 mm) of water column (500 Pa) pressure
classification shall not require additional closure systems.
Duct tightness shall be verified by either of the following:
1. Postconstruction test:
Total leakage to the outside of a conditioned space or total leakage shall be
less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29
m2) of conditioned floor area when tested at a
pressure differential of 0.1 inches (2.54 mm) w. g. (25 Pa) across the entire
system, including the manufacturers air handler enclosure. All register boots
shall be taped or otherwise sealed during the test.
2. Rough-in test: Total leakage shall be less
than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29
m2) of conditioned floor area when tested at a
pressure differential of 0.1 inches (2.54 mm) w.g. (25 Pa) across the system,
including the manufacturers air handler enclosure. All registers shall be taped
or otherwise sealed during the test. If the air handler is not installed at the
time of the test, total leakage shall be less than or equal to 3 cfm (85 L/min)
per 100 square feet (9.29 m2) of conditioned floor
area.
Exception: The total leakage test is not required for ducts and air handlers located entirely within the building thermal envelope.
N1103.4.2. Hot water pipe insulation
(prescriptive). Insulation for hot water pipe with a minimum thermal resistance
(R-value) of R-3 shall be applied to the following:
1. Piping larger than 3/4 inch nominal
diameter.
2. Piping serving more
than 1 dwelling unit.
3. Piping
located outside the conditioned space.
4. Piping from the water heater to a
distribution manifold.
5. Piping
located under a floor slab.
6.
Buried piping.
7. Supply and return
piping in recirculation systems other than demand recirculation
systems.
Notes
State regulations are updated quarterly; we currently have two versions available. Below is a comparison between our most recent version and the prior quarterly release. More comparison features will be added as we have more versions to compare.
Rule 547e.
Sections N1103.2.1, N1103.2.2, and N1103.4.2 of the
N1103.2.1. Insulation (prescriptive). All portions of the air distribution system shall be installed in accordance with Section M1601 and be insulated to an installed R-6 when system components are located within the building but outside the conditioned space, and R-8 when located outside to the building thermal envelope. When located within a building envelope assembly, at least R-8 shall be applied between the duct and that portion of the assembly farthest from conditioned space.
Exception: Portions of the air
N1103.2.2. Sealing (mandatory). Ducts, air handlers, and filter boxes shall be sealed. Joints and seams shall comply with either the international mechanical code or international residential code , as applicable.
Exceptions:
1. Air-impermeable spray foam products may be applied without additional joint seals.
2. Where a duct connection is made that is partially inaccessible, 3 screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.
3. Continuously welded and locking-type longitudinal joints and seams in ducts operating at static pressures less than 2 inches (51 mm) of water column (500 Pa) pressure classification shall not require additional closure systems.
Duct tightness shall be verified by either of the following:
1. Postconstruction test : Total leakage to the outside of a conditioned space or total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches (2.54 mm) w. g. (25 Pa) across the entire system , including the manufacturers air handler enclosure. All register boots shall be taped or otherwise sealed during the test .
2. Rough-in test : Total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches (2.54 mm) w.g. (25 Pa) across the system , including the manufacturers air handler enclosure. All registers shall be taped or otherwise sealed during the test . If the air handler is not installed at the time of the test , total leakage shall be less than or equal to 3 cfm (85 L/min) per 100 square feet (9.29 m2) of conditioned floor area.
Exception: The total leakage
N1103.4.2. Hot water pipe insulation (prescriptive). Insulation for hot water pipe with a minimum thermal resistance (R-value) of R-3 shall be applied to the following:
1. Piping larger than 3/4 inch nominal diameter.
2. Piping serving more than 1 dwelling unit.
3. Piping located outside the conditioned space.
4. Piping from the water heater to a distribution manifold.
5. Piping located under a floor slab.
6. Buried piping.
7. Supply and return piping in recirculation systems other than demand recirculation systems.