Mini split systems are a popular way to heat and cool residential and light commercial buildings. When an outdoor condenser is installed on a flat roof, it needs a properly designed support stand that provides the required clearance, distributes the equipment load, protects the roof surface, and is suitable for outdoor conditions.
Why a Mini Split Condenser Needs Proper Roof Support
When a mini split condenser is installed on a flat roof, the mounting arrangement needs to provide the clearances, support, and roof protection required for the installation.
Clearance and drainage. Elevating the condenser above the roof surface provides clearance beneath the unit and keeps the equipment above the roof surface. Always follow the equipment manufacturer's requirements for clearances, drainage, and installation orientation.
Airflow. Mini split manufacturers specify minimum clearances around their outdoor units. Blocking the required clearance can restrict airflow around the coil and affect equipment performance. Always check the manufacturer's installation requirements before selecting a support stand.
Membrane protection. A condenser mounted directly on a roof membrane can concentrate its load over a relatively small footprint. Wider support bases can help distribute the equipment load across a larger area.
A properly selected stand can help address these requirements by elevating the unit, distributing the load through the support bases, and maintaining appropriate clearance from the roof surface.
What to Look for in a Flat Roof Mini Split Stand
Roof-resting bases. Look for support bases designed to distribute equipment loads across the roof surface without unnecessarily concentrating the load in a small area. MIRO-CG's MMS-18 uses 8 × 8-inch polycarbonate bases designed to protect the roof membrane, while the Rail Support uses polycarbonate bases with four 12 × 12-inch rubber support pads placed underneath them.
UV-resistant base material. MIRO-CG uses polycarbonate bases with carbon black for UV resistance. This provides a non-metallic base material between the support structure and the roof surface.
Width adjustability. Mini split condensers vary in size depending on the manufacturer and model. An adjustable-width support can accommodate a wider range of equipment dimensions without requiring a custom support.
Height adjustability. Flat roofs can have slopes or uneven areas. An adjustable-height support can accommodate installations where additional height adjustment is required.
Corrosion-resistant frame. Rooftop supports are exposed to moisture and outdoor conditions, so galvanized steel construction can provide corrosion resistance for long-term outdoor use.
MIRO-CG's Mini Split Stand Options
MIRO-CG offers two mini split condenser support systems for rooftop and flat-surface installations. Both use polycarbonate bases with carbon black for UV resistance and galvanized steel framing. The appropriate configuration depends on the condenser's dimensions, weight, required height, and installation conditions.
Mini Split Condenser Stand (Rail Support)
The Mini Split Condenser Stand is designed for height, width, and span adjustability across a wide range of mini split units. It uses 12-gauge, 13/16-inch HDG (hot-dip galvanized) channel and is fully adjustable. The hardware and brackets are either hot-dip galvanized or electro-galvanized.
The Rail Support includes four 12 × 12-inch rubber support pads designed to be placed underneath the polycarbonate bases. The pads provide an additional layer between the bases and the roof surface.
Key specs:
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Frame: 12-gauge, 13/16-inch HDG channel
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Base: Polycarbonate with carbon black for UV resistance
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Includes: Four 12 × 12-inch rubber support pads
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Optimized rooftop loading: 3.0 PSI, approximately 300 lbs
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Loading: Designed for gravity loading; additional wind and/or seismic tie-downs and engineering are available upon request
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Ultimate load capacity: Not tested
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Warranty: 2-year limited
Best for: Installations where greater height, width, and span adjustability is needed, or where the condenser falls outside the MMS-18's dimensional range.
MMS-18 Mini Split Condenser Stand
The MMS-18 is designed for mini split condenser units with frame widths from 10-1/2 to 18 inches. For the Standard configuration, the frame-to-frame dimension should not exceed 48 inches.
The frame is made from 1/4-inch A366 steel and hot-dip galvanized. The Standard version uses 8 × 8-inch polycarbonate bases with carbon black for UV resistance.
Two versions are available:
Standard (MMS-18)
The Standard configuration has a fixed height of 12-1/8 inches with the polycarbonate bases, or 10 inches on the frame only.
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Height: 12-1/8 inches with polycarbonate bases; 10 inches on frame only
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Optimized rooftop loading: 3.0 PSI, approximately 300 lbs with four bases
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Warranty: 2-year limited
The fixed-height design is suitable when the 12-1/8-inch height meets the installation requirements and the roof surface does not require height adjustment.
Adjustable (MMS-18A)
The Adjustable configuration uses an all-thread connection that allows the height to be adjusted for uneven roof surfaces and slopes.
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Height: Adjustable from 12-3/8 inches minimum to 14-5/8 inches maximum
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Optimized rooftop loading: 3.0 PSI, approximately 600 lbs with four bases
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Warranty: 2-year limited
The all-thread connection allows height adjustment to accommodate uneven roof surfaces and slopes.
Which One Should You Buy?
Start with the condenser's dimensions and weight. These are important factors when determining which stand configuration is appropriate.
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Unit is 10-1/2 to 18 inches wide: The MMS-18 Standard or Adjustable may be appropriate, provided the complete footprint, dimensions, and load requirements are within specification.
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Unit falls outside the MMS-18's dimensional range, or you need greater height, width, and span adjustability: Consider the Rail Support.
If the MMS-18 fits your unit:
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Roof is relatively flat and the fixed height meets the installation requirements: The Standard MMS-18 provides a fixed 12-1/8-inch height with the polycarbonate bases.
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Roof has uneven areas or a slope requiring height adjustment: The MMS-18A Adjustable uses an all-thread connection to adjust the height from 12-3/8 to 14-5/8 inches.
Quick check: Pull the specification sheet for your mini split and check the unit's frame width, complete footprint, weight, and required clearances. If the frame width is between 10-1/2 and 18 inches, the MMS-18 may be an option. Confirm the complete installation requirements before ordering.
Installation Tips
Check the manufacturer's clearance specifications first. Mini split manufacturers specify minimum clearances around their outdoor units. Review the equipment installation manual before selecting the stand and its height.
Level the unit. Follow the manufacturer's requirements for unit leveling, clearances, and condensate drainage. The Rail Support provides height adjustability as part of its overall rail configuration, while the MMS-18A uses an all-thread connection to adjust the height for uneven roof surfaces and slopes.
Use the rubber pads. The Rail Support includes four 12 × 12-inch rubber support pads designed to go underneath the polycarbonate bases. Use them as specified by the manufacturer to provide an additional layer between the bases and the roof surface.
Plan service clearance. Leave sufficient space around the condenser for maintenance and service. Follow the equipment manufacturer's installation requirements for side, rear, top, and other required clearances.
Consider wind and seismic conditions. The Rail Support is designed for gravity loading, with additional wind and/or seismic tie-downs and engineering available upon request. For high-wind or seismic applications, contact MIRO-CG before installation.