For a MEWP, the machine’s own markings and applicable operator’s manual set the wind limit. A 12.5 m/s rating is common for outdoor machines, not a universal permission; an indoor-only lift is not suitable outdoors simply because the day seems calm. For a purchase, also confirm the permitted outdoor working height, occupants, load and configuration.
The difference between indoor and outdoor limits is about the operating conditions allowed for the machine, not simply how far its platform can physically extend.
1. What does a 12.5 m/s wind rating mean?
Many outdoor-rated MEWPs have a stated maximum wind speed of 12.5 m/s—equivalent to 45 km/h or approximately 28 mph.
That figure appears in common MEWP rating practice, but it is not a universal permission to operate every lift outdoors at that wind speed. The limit for the particular machine must come from its data plate, markings and operator’s manual. Some machines are indoor-only; others have different outdoor modes or restrictions.
See IPAF’s guidance on MEWP wind ratings.
Wind applies horizontal force to the platform, occupants, boom or scissor structure and anything carried in the platform. Because that force acts above ground level, it also creates an overturning moment.
In simplified terms, that moment depends on the horizontal force and the height at which it acts. Exposed area and the geometry of the load matter as well.
Wind effects also rise faster than wind speed alone suggests. With air density and other conditions unchanged, dynamic pressure is proportional to the square of wind speed. Moving from 10 m/s to 12.5 m/s raises the dynamic pressure by about 56%.
That relationship explains the sensitivity to stronger wind; it is not a way to calculate the stability margin of a particular MEWP. Actual forces depend on shape, orientation, loading and the manufacturer’s assumptions.
2. Does the quoted maximum working height also apply outdoors?
Consider two supplier quotations that both highlight a lift’s maximum working height but say nothing about indoor or outdoor conditions. The headline figure alone does not show whether that height is permitted outdoors.
Ask each supplier to confirm the indoor and outdoor working-height limits for the exact model and offered configuration, along with permitted occupants and platform load. Request the specification and applicable manual version that support each figure; outdoor limits vary by machine and configuration.
See the guide to working and platform heights for the relevant checks.
The lifting mechanism has not lost physical travel because the machine moved outside. Rather, the permitted operating envelope changes when outdoor forces must be considered.
Wind is not the only variable. Maximum numbers of occupants, platform capacity, lateral force and chassis tilt can also be subject to different limits. Do not assume every dual-rated lift uses the same reduction in outdoor height.
3. “Indoor only” does not mean “outdoors when it feels calm”
A marking such as Indoor Only — 0 m/s indicates that the machine’s permitted operating conditions do not include wind loading. It does not make outdoor operation acceptable simply because the weather forecast says “light breeze”.
IPAF explicitly warns against taking an indoor-only machine into an outdoor exposed environment based on how calm conditions appear at that moment. See its wind-rating guidance.
Nor does a roof automatically make a site wind-free. A factory building with its roof installed but open sides can experience strong through-draughts. Large warehouses and hangars with substantial open doors can present similar conditions.
The useful question is not simply whether workers are “inside”. It is whether the platform’s actual position is exposed to wind and whether the machine is rated for those conditions.
4. Why ground-level weather is a poor guide to wind at height
A building may shelter the machine at ground level while the raised platform is exposed above a parapet or roof edge. Airflow can also accelerate around corners or between buildings.
IPAF notes that wind speed at platform height may be markedly different from that felt on the ground. Local obstructions can both shelter and channel the airflow. See IPAF’s wind-speed FAQ.
A forecast helps plan work, but it does not establish conditions at the platform. The relevant assessment includes wind and gusts at the actual working position, with appropriate measurement using an anemometer where required by the work arrangements and guidance.
5. Why a large panel changes the picture
Suppose an outdoor-rated platform has a maximum stated wind speed of 12.5 m/s. Two workers now want to position a large glazing panel in an 8 m/s wind. Is that automatically acceptable?
No. A pane of glass, cladding sheet, advertising panel or similar item can add considerable exposed area. The additional horizontal force can be significant even when the material is relatively light.
This is the sail effect. Platform capacity is primarily a weight rating, not permission to introduce unlimited wind area or lateral loading. IPAF warns that banners and other large exposed items can affect a MEWP’s stability; see its toolbox talk.
When a job involves large sheets or specialist handling accessories, the buyer or user needs the manufacturer’s permitted arrangement and a suitable task assessment. Being below the weight limit does not prove that the wind-loading conditions are acceptable.
6. What to confirm before buying a lift for outdoor work
| Item | What to request |
|---|---|
| Maximum rated wind speed | Value, units and conditions for the exact machine |
| Indoor/outdoor status | Whether outdoor operation is permitted and whether modes differ |
| Maximum outdoor working height | Do not substitute the indoor figure |
| Outdoor persons and capacity | Any change in allowable occupancy or load |
| Other restrictions | Chassis tilt, lateral forces and relevant stability conditions |
| Evidence | Data plate and labels plus the applicable operator’s manual |
A supplier request can be direct:
If the supplier’s reply is incomplete:
| Situation | Buyer’s next step |
|---|---|
| Supplier says only “suitable for outdoor use” | Request the exact model, offered configuration, applicable limits and the matching specification and operator’s-manual references. |
| Quotation, specification and manual do not match | Ask the sales contact to obtain written clarification from technical staff, tied to the documents and configuration. A sales assurance cannot override the manufacturer’s limits. |
| New machine has not been built, so there is no nameplate photo | Check the proposed model’s documentation when comparing quotations, then verify before delivery that the actual machine markings match the agreed documents. |
Missing documents alone do not prove that a machine is unsuitable, but a vague reply cannot establish that it fits the intended work. Checking documents against the nameplate is not a wind test or approval to operate.
Once the supplier replies, record the outdoor-use limits and document references alongside each quotation. For scissor lifts, use the quotation comparison table to compare offers on the same basis.
For a machine already ordered, include checks of the agreed data plates, labels and documentation in the pre-shipment inspection scope. These checks verify document and nameplate consistency; they are not a wind-resistance test or approval to operate.
A wind rating defines one boundary of the machine’s permitted use. It does not override the conditions of the site, the load or the task.