Awning Motors Explained: Torque Sizing, Limits, Radio vs Wired, and Battery Options
Quick answer
Awnings are driven by tubular motors that fit inside the roller tube and are rated by torque in newton-meters (Nm) and speed in rpm. Window shades and drop-arm awnings often need roughly 6 to 20 Nm, while lateral-arm patio awnings commonly use about 30 to 120 Nm depending on width, projection and arm spring tension. Match motor diameter to the tube, size torque from the manufacturer's chart with a margin, and choose radio or wired control based on how many awnings and sensors you will run.
An awning motor is a tubular motor: a sealed cylinder containing an electric motor, a reduction gearbox, a brake and limit electronics, which slides inside the awning's roller tube and turns it. You choose one by three numbers and one decision: diameter (it must fit the tube), torque in newton-meters (it must lift the load with margin), speed in rpm, and the control type (radio, wired, or both). Get those right and a quality motor commonly lasts 10 years or more; get torque wrong and it will overheat, stall or wear out its brake early.
This guide goes deep on the motor itself. For the bigger picture on choosing and pricing a motorized awning, start with our motorized awnings guide.
Anatomy of a tubular motor
- Motor head. The exposed end that bolts into the awning's end bracket. It carries the cable entry, and on many motors the limit-adjustment screws or a programming button.
- Motor body. Usually an AC induction motor on 120 V US models (or a DC motor on battery and 12 V units), with a planetary gearbox that trades speed for torque.
- Brake. Holds the tube when power is off so the arm springs cannot unroll the fabric. This is why a motorized awning stays put without a crank gear.
- Crown and drive adapters. The crown centers the motor at the head end; the drive wheel at the far end locks into the tube's internal profile. These must match the tube's exact shape (round, octagonal, or a grooved profile).
- Thermal protection. A cutout that stops the motor after a few minutes of continuous running and resets after it cools.
Common diameters are about 35 mm (1.4 in) for smaller shades, 45 mm (1.8 in) for most residential awnings, and 50 to 60 mm (2 to 2.4 in) for large or heavy systems. The motor must fit the tube's inside dimension with the correct adapters, so measure the tube or get the part number from the awning maker before buying.
Sizing torque in newton-meters
Torque is the turning force the motor can produce, rated in newton-meters (Nm). One Nm is roughly the twisting force of a 0.225 lb weight hanging from a 1 m (3.3 ft) wrench, or about 0.74 lb-ft. What the motor must overcome depends on the awning type:
- Drop shades, screens and drop-arm awnings: mostly the weight of the fabric and bottom bar, acting at the radius of the rolled fabric. Loads are modest.
- Lateral-arm awnings: the dominant load is not fabric weight but the arm springs. The arms constantly push the front bar outward, so retracting means pulling against that spring force over the full width. Wider awnings with more or stronger arms need much more torque.
| Application | Typical torque | Typical speed |
|---|---|---|
| Small window shades and screens | About 6 to 10 Nm | About 17 to 30 rpm |
| Drop-arm window awnings, larger screens | About 10 to 20 Nm | About 17 to 30 rpm |
| Lateral-arm awnings up to about 12 to 14 ft wide | About 30 to 50 Nm | About 12 to 17 rpm |
| Wide lateral-arm and pergola systems | About 50 to 120 Nm | About 9 to 12 rpm |
Higher-torque motors usually turn more slowly because the gearbox trades speed for force. That is acceptable: a wide awning that takes 60 to 90 seconds to retract is normal.
Worked example
A 10 ft wide exterior drop shade has 8 ft of fabric. At roughly 1 oz per square foot, the fabric weighs 10 x 8 = 80 oz, or 5 lb. The weighted bottom bar adds about 1 lb per foot, so 10 lb. Total hanging load: 15 lb, which is about 6.8 kg or 67 newtons.
With fabric rolled up, the effective radius is about 1.6 in (0.04 m). Torque needed: 67 N x 0.04 m = 2.7 Nm. Doubling that for friction, side-track drag and a safety margin gives about 5.4 Nm, so a 6 Nm motor works and a 10 Nm motor is comfortable.
The same arithmetic does not work for a lateral-arm awning, because arm spring tension, not weight, sets the load. For those, use the manufacturer's torque table by width, projection and arm count.
Do not oversize blindly: A much stronger motor than needed can damage the awning if something jams, because it will keep pulling until its obstacle detection (if any) or limit stops it. Pick the rated torque from the chart, then step up one size at most.
Limit settings: mechanical vs electronic
Limits tell the motor where to stop at full open and full closed. There are two systems:
- Mechanical limits. Two adjustment screws on the motor head, usually marked with arrows, turned with a hex or limit tool. Each turn moves the stop point by a fraction of a tube rotation. They are simple and survive power loss, but require access to the motor head.
- Electronic limits. Set with the remote or a programming button: you drive the awning to the desired position and store it. Many electronic motors also store an intermediate "favorite" position and can detect a hard stop at the closed position for a firm seal in cassette awnings.
- Set the closed limit first. The front bar should seat snugly against the cassette or hood without the motor straining or the fabric buckling.
- Set the open limit short of full unroll. Leave at least one wrap of fabric on the tube. Unrolling to the bare tube can stress the fabric attachment and, on some awnings, rewind the fabric in the wrong direction.
- Check fabric tension. At full extension the fabric should be taut, without sagging between arms. If it sags, the open limit is set too far.
- Cycle three times. Confirm the motor stops in the same places and does not stall or hum at either end.
Lost or drifting limits are a common service call; our motorized awning troubleshooting guide explains what causes them.
Radio (RTS and similar) vs wired control
Motors are sold as wired (switch control only), radio (built-in receiver), or hybrid.
| Factor | Wired | Radio |
|---|---|---|
| Control | Up/stop/down wall switch | Remotes, wireless wall switches, sensors, hubs |
| Wiring | Power plus switch leg to the switch location | Power only at the motor |
| Sensors | Need a separate control box | Pair directly with compatible sensors |
| Group control | Needs a group control module; never wire two motors to one switch in parallel | Assign several motors to one remote channel |
| Failure points | Switch and wiring | Remote batteries, radio range, pairing memory |
Somfy's RTS (Radio Technology Somfy) is a long-established one-way radio system widely used on awnings in North America: the remote sends commands but the motor does not report back. Somfy's io-homecontrol is a two-way protocol, so a controller can confirm the awning actually moved. Other motor makers use their own radio systems, and some newer motors include Wi-Fi, Zigbee or other smart-home radios. Remotes and sensors generally only work with motors that speak the same protocol, so pick the protocol before buying accessories. Linking to apps and voice control is covered in smart home awning control.
Battery and solar motors
Battery motors use a lithium pack, either inside the tube or in a separate wand, and many charge from a small solar panel mounted on the cassette or wall. They remove the need for wiring, which makes them attractive for window awnings, second-storey screens and rentals.
Limits: battery motors generally offer less torque than mains motors and suit lighter loads. Cycle count per charge drops in cold weather, and a north-facing or heavily shaded panel may not keep up in winter. Lithium packs age, so expect to replace the battery after several years. For a large lateral-arm awning used daily, a 120 V motor remains the reliable choice.
Manual override
A manual override motor has a fitting on the head that accepts a crank wand, so the awning can be retracted by hand during a power cut or motor failure. It adds cost and requires the motor to sit on the end where the crank can reach it. It is worth requesting if you live in an area where storms and outages arrive together, if the awning is large, or if there is no wind sensor. Without an override, a dead motor can leave an extended awning stranded until a technician removes it.
Somfy and the alternatives
Somfy, a French company, is the most widely recognized awning motor brand in the US and supplies many awning manufacturers. Its RTS remotes and sensors are common, and its TaHoma hub provides app control. Other established tubular motor makers include Becker and Elero (both German), Nice (Italian) and Simu (French), and many direct-to-consumer awnings use motors from lower-cost Asian manufacturers. Quality varies within every tier.
What matters more than the logo:
- Can the dealer or maker supply a replacement motor and remote in five or eight years?
- Does the motor's protocol work with the sensor and hub you want?
- Is the motor warranty (typically about five years) honored directly by the awning seller?
- Are torque and diameter documented, so an equivalent motor can be fitted later?
When comparing awning brands overall, see best retractable awning brands. To estimate the price of a motor upgrade, the awning cost calculator includes motor and sensor options.
Replacing or upgrading a motor
Replacing a motor means removing the roller tube (usually with the awning retracted and arms secured, because arm springs store significant energy), sliding out the old motor, fitting adapters to the new one, reinstalling and setting limits. Motor parts for a compatible awning usually run about $400 to $1,300 depending on torque and features. If you are adding a motor where there was a crank, read converting a manual awning to motorized first.
Arm springs are dangerous: Lateral-arm springs are under heavy tension even when retracted. Never release arm straps or remove a tube from an extended awning. Many manufacturers recommend professional service for motor replacement on lateral-arm units.
Frequently asked questions
How much torque does an awning motor need?
It depends on the awning type and size. Window shades and drop-arm awnings typically need about 6 to 20 Nm, while lateral-arm patio awnings commonly use roughly 30 to 120 Nm, because the motor must pull against the arm springs. Use the awning manufacturer's torque table based on width, projection and number of arms, and avoid stepping up more than one size beyond the recommendation.
What is the difference between RTS and io-homecontrol?
Both are Somfy radio protocols. RTS is one-way: remotes and sensors send commands, but the motor does not confirm what it did. io-homecontrol is two-way, so a compatible controller or app can receive feedback that the awning moved or reached a position. Accessories for one protocol do not control motors on the other, so confirm which your motor uses before buying remotes or hubs.
Can I replace a Somfy motor with a different brand?
Often yes, if the replacement has the right diameter, similar torque and speed, and adapters that fit your roller tube's profile. You will also need new remotes and sensors that match the new motor's protocol, and the end bracket may need an adapter plate. Check that the motor head fits the existing bracket before ordering, or ask the awning maker for a cross-reference.
Why does my awning motor stop after a few cycles?
Tubular motors include thermal protection that cuts power after a few minutes of continuous running, to prevent overheating. Repeated open and close cycles, or a motor that is undersized for the awning, will trigger it. The motor resets after cooling, commonly 15 to 30 minutes. Frequent tripping during normal use suggests the motor is working too hard.
Are battery awning motors strong enough for a patio awning?
For small and medium window awnings and screens, usually yes. For large lateral-arm patio awnings, battery motors are often at the edge of their torque range, and frequent daily cycling can drain them faster than a small solar panel recharges. A 120 V motor is the more reliable choice for wide patio units used every day.
Sources and further reading
- Somfy: technical documentation for tubular motors, RTS and io-homecontrol
- European Committee for Standardization, EN 13561: External blinds and awnings, performance requirements including safety
- National Fire Protection Association, NFPA 70: National Electrical Code
- UL Standards & Engagement, UL 325: Standard for door, drapery, gate, louver and window operators and systems
How we write our guides: figures are typical US ranges checked against manufacturer documentation, published standards and installer pricing. Read our editorial standards. Spotted an error or outdated detail? Request a correction.