Access to mechanical
equipment and appliances installed in underfloor areas, in attic spaces, and on
roofs or elevated structures shall be in accordance with this section and the
Minnesota Mechanical Code.
1209.3.1
Mechanical equipment and appliances on roofs or elevated structures.
Where mechanical equipment or appliances requiring periodic inspection,
service, or maintenance are installed on roofs or elevated structures, a
permanent stair shall be provided for access.
Exception: A portable ladder may be used for
dwellings, replacement equipment and appliances on existing buildings, and
exterior roof access points not exceeding 16 feet (4.9 m) above grade, unless
the building official determines that the unique shape of the roof does not
allow safe access with a portable ladder.
The permanent stair shall at a minimum, meet the
following:
1. The stair shall be
installed at an angle of not more than 60 degrees measured from the horizontal
plan;
2. The stair shall have flat
treads at least six inches (152 mm) deep and a clear width of at least 18
inches (457 mm) with equally spaced risers at least 10.5 inches (267 mm) high
and not exceeding 14 inches (356 mm);
3. The stair shall have intermediate landings
not exceeding 18 feet (5.5 m) vertically;
4. The stair shall be installed with
continuous handrails on both sides of the stair;
5. interior stairs shall terminate at the
underside of the roof at a hatch or scuttle of at least 8 square feet
(0.74m2 ) with a minimum dimension of 20 inches (508
mm);
6. a roof access hatch or
scuttle shall be located within 10 feet (3.0 m) of a roof edge, and a guard
shall be installed in accordance with this code and
7. exterior stairs shall terminate at the
roof access point or at a level landing of at least 8 square feet
(0.74m2 ) with a minimum dimension of 20 inches (508
mm). The landing shall have a guard installed in accordance with IMC section
304.9.
1209.3.1.1
Permanent
ladders. Where a change in roof elevation greater than 30 inches (762
mm) but not exceeding 16 feet (4.9 m) exists, a permanent ladder shall be
provided. The ladder may be vertical .The ladder shall, at a minimum, meet the
following:
1. Width shall be at least 16
inches (406 mm).
2. Rung spacing
shall be at maximum of 14 inches (356 mm).
3. Toe space shall be at least 6 inches (152
mm).
4. Side railings shall extend
at least 30 inches (762 mm) above the roof or parapet wall.