Retrofit vs Built-In Motorized Shades: Pre-War Windows, What a Kit Can Drive, Power With No Outlet, and Which to Choose

Can you motorize existing blinds, or do you need new shades?

There are two ways to end up with a shade that moves on its own: bolt a motor onto blinds you already own, or buy the shade with the motor built into the tube at the factory. The right one depends less on which is "better" than on what is on the window now and what the window itself is like, and in an older house the window decides.

A retrofit kit adds a motor to a manual shade: a small drive that turns the bead chain on a roller, zebra, or cord-loop cellular shade; a motorized wand that tilts the slats of a horizontal blind; or a replacement roller tube with a motor inside that reuses your fabric.

A built-in motor means the shade is manufactured motorized: the motor lives inside the tube, sized to that fabric and width, with limits preset and the remote paired. This is what SelectBlinds, SmartWings, and Graywind sell; the site's picks are in the best motorized shades roundup.

This guide is built around the case that is rarely answered: a pre-war window with a deep plaster jamb, no outlet within reach, sash weights behind the trim, and woodwork nobody is allowed to drill.

What makes pre-war windows a special case for motorized shades?

Old windows are harder because five things a motorized shade assumes are often missing at once.

Deep, out-of-square jambs. A plaster return on a masonry wall gives far more depth than a vinyl replacement, which helps an inside mount, but the opening was framed by hand and has settled since. Width at the top, middle, and bottom can differ by a real fraction of an inch, and the headrail only cares about the narrowest one.

Pulleys and sash cords at the top of the jamb. On a weighted double-hung, the pulley plates sit exactly where an inside-mount headrail wants to go. A chain-drive box hanging beside the roller can foul a cord; a motorized tube needs clear depth in front of the pulleys.

Plaster and lath, and no outlet near the window. Fishing low-voltage wire through plaster is slow, dusty work, and that wire is exactly what a hardwired motor needs. That pushes old houses toward battery, solar-assisted battery, or a plug-in motor on the rare window near a receptacle.

Tall, heavy sashes. The shade that covers a pre-war window is tall and heavy. A retrofit chain drive has a torque limit set by the kit; a built-in motor is chosen by the factory for the size you order.

Trim you cannot drill. A landmark designation or a lease rules out an outside mount on the trim, not motorization: an inside mount into the jamb hides its holes behind the shade, a mounting board above the casing carries the brackets, and a no-drill headrail avoids screws altogether; SelectBlinds lists a Click2Fit No-Drill configuration on its motorized Architect blackout page, capped on size (figures in the table below).

What is a retrofit motor kit, and what can't it drive?

Kits come in three shapes, and the shape decides what they move.

A bead-chain driver clamps beside a continuous-loop shade and turns the chain the way your hand would. It works only on shades that have a chain: roller, zebra, and some cellular and Roman shades with a cord loop. It cannot drive a cordless spring-lift shade or a top-down bottom-up, because there is no chain to turn. Its capacity is whatever the kit's own rating says, and a tall pre-war blackout roller can sit above it; the kit stalls or wanders rather than announcing the problem.

A tilt-wand motor replaces the wand on a horizontal blind. It tilts the slats; it does not raise or lower the blind.

A replacement tube motor swaps your roller's tube for one with a motor inside, reusing the fabric. It is the most work: tube diameter, bracket spacing, and fabric width all have to match, and once you have priced the tube, brackets, and a remote, you are close to a factory shade.

Every kit is a two-part system. The motor maker did not build your shade and the shade maker did not build the motor, so limits, noise, mounting, and support are split between two companies. That is fine on a good shade in an easy window. It is a poor bet on a heavy shade in an out-of-square opening, where the seams in a two-part system are where trouble shows up.

When is a purpose-built motorized shade cheaper than converting?

Run the arithmetic per window; the answer flips on what is already hanging there.

If the window is bare or the shade is tired, built-in wins almost every time. You are buying a shade regardless; the motorized version of the same fabric costs more than the cordless version, but less than a manual shade plus a kit plus the pieces the kit does not include.

If you own good, recent manual shades, retrofit can be cheaper for a room, because it spares you replacing fabric that is fine. The catch is the hidden line items: a chain driver that needs its own remote, a charging cable, and a bridge for app control quickly costs more than its sticker. Hold the two totals side by side, and count the bridge on both sides.

No price makes a kit a bargain on a shade too heavy or wide for it; the size table below shows what a factory motor is built to carry. Dollar figures are deliberately not quoted here, because sale pricing on custom shades changes constantly; configure the exact window on the seller's site and add every accessory. The motorized vs cordless comparison covers where the motor premium lands against a manual shade.

Battery, hardwired, solar trickle, or plug-in: what works with no wiring near the window?

Power is the decision an old house makes for you. The power options guide has the general logic; here is what the sellers publish.

Rechargeable battery is the default and the pre-war answer. SelectBlinds' motorized Architect page says its remote-motorization battery is "rechargeable with USB C cable," that "a full battery charge will last up to 12 months based on an average-sized shade raised and lowered once a day," and that it "takes approximately 6 hours to recharge the motor when fully depleted." Its Automation line on the Sheer Weave page runs "around 6 months" under the same use, and its 10-foot charging kit "allows shades to be charged right in the window." SmartWings puts its motor at "4-6 months" per charge; Graywind says to "charge the shade with the given USB cable every 3~6 months." The shape is the same: a few charges a year, in place, no wiring. The battery life guide explains why heavy, tall, busy shades sit at the short end of every range.

Solar trickle adds a small panel that tops the battery up through the glass. SmartWings states that "all SmartWings motorized shades can be paired with a solar panel," that "direct sunlight is strongly recommended," and that "each solar panel is designed to power one motorized shade." Treat solar as a way to stretch the interval, not skip charging; a deep reveal and a storm pane both cut what reaches the panel.

Hardwired removes charging and asks for a wire at the window. SmartWings says its hardwired shades come "with 12V DC or 110V-240V AC motors" and also sells a Power over Ethernet motor that runs power and data over one network cable, "up to 328 feet" from the switch, pitched for "large or heavy blinds that require a stable power supply." Graywind's installation FAQ says "rechargeable battery motors usually do not require an electrician" while hardwired motors "should be handled by a qualified professional."

Plug-in is the middle path. Graywind offers a "hardwired WiFi motor" that "stays plugged in for continuous power," recommended "for locations with accessible power outlets." If the room's one outlet is beside the window, this needs no electrician.

Hubs and remotes, in one paragraph

Every shade above works without a hub, from its remote or, on SelectBlinds' Automation line, from the phone app; each brand attaches smart-home control differently, so read the hub guide and the protocols guide. SelectBlinds' Automation line pairs with the SelectBlinds Automation Bridge, which its page says brings "Apple Home, Google Home, Amazon Alexa, and SmartThings — all powered by Matter," supports "up to 15 shades per home," and allows "only one bridge" per network for now; its remote-motorization line uses the separate SelectConnect Bridge (Bond Home app, "approximately 150' or 30 blinds/shades," listed at $199.98 when fetched for this guide, not compatible with the Automation system); its motorized-wand option is an Eve MotionBlinds motor with "built-in Matter/Thread technology." SmartWings' Matter motor needs "a hub or device with both Thread Border Router and Matter Controller functions"; its Zigbee and Z-Wave motors go through SmartThings, Home Assistant, or Hubitat. Graywind's Bluetooth motor needs its "Bluetooth Hub" for "schedules, routines, group control, Alexa, and Google integration," its Zigbee motor joins "Alexa devices that include a built-in Zigbee hub" directly, and a Matter over Thread motor is offered on "select products." With a retrofit kit, all of this comes from the kit maker, not the shade maker.

How wide and how heavy can a motorized shade go?

None of the three brands' product pages publish a weight limit in pounds. They publish a size envelope, and the factory picks the motor for the size, so the envelope is the limit.

Every envelope starts around 20 inches, so a narrow sidelight may fall below the minimum, and every one tops out near a wide picture window, past which you split the opening, as the wide window guide explains. For a tall bedroom sash that needs real darkness, SelectBlinds' motorized Architect blackout roller in Light Drizzle is the configured example behind the first row. For a south-facing parlor window where you want the view and not the glare, the motorized Sheer Weave solar in Charcoal 14% is the open-weave end of the second row.

A retrofit kit publishes its own capacity, and that is the number to hold your existing shade against; lift it off the brackets and weigh it on a bathroom scale if you have to. A rating that is close is a motor that lives at its limit.

Retrofit vs built-in: the decision table

Choose a retrofit kit when, choose a built-in motor when

Choose a retrofit kit when the shade already on the window is a good continuous-loop roller or zebra you would not otherwise replace; its weight sits comfortably inside the kit's published rating; and the window is reachable enough that a drive box on the headrail is acceptable to look at and to charge.

Skip the retrofit when the existing shade is cordless, top-down bottom-up, or a heavy blackout on a tall opening; or when you want one company answering for the whole assembly.

Choose a built-in motorized shade when the window is bare or due for new fabric; when you need the factory to size the motor to a tall or wide pre-war sash; when charging access, a no-drill headrail, or a plug-in motor solves the power and trim problems in one order; and when the fit is worth a remake policy. SmartWings' motorized roller shades are a purpose-built example, with battery, hardwired, and PoE power on selected models; the SmartWings review covers its strict custom-order policy, and the Graywind review covers the more forgiving fit guarantee on that brand's zebra line. The motorized Sheer Weave solar in Cream Haze 5% is the Automation-line example: app control, scenes, and timers with no remote required, and the Automation Bridge for smart-home platforms.

Skip the built-in when you own shades you like that fall inside a kit's rating, or the window is narrower than the table's minimums.

How do you measure a deep, out-of-square old frame for a motorized shade?

A motor tightens the tolerances: the headrail is deeper and the shade heavier. Start with the inside mount and outside mount definitions and the inside vs outside mount guide, then work the old-house list.

Measure depth to the frontmost obstruction, not the glass. On a weighted sash that is usually the pulley plate or the sash lock; with an interior storm it is the storm frame. The minimum mount depth guide explains the method, and the motorized figures in the table above are the ones to clear.

Take the width at three heights and send the narrowest. SmartWings' measuring page says that for a "splayed or recessed frame" you should "measure the shortest width and use that measurement when placing your order," and to "round down to the nearest 1/8 inch" on width. SelectBlinds says to round a 1/16 or 1/32 increment "down to the nearest 1/8"." Graywind asks for "the nearest 1/8 inch" and invites a "front-facing photo of the window" when the shape does not match its guide.

Do not deduct. Every seller applies its own deductions; SelectBlinds' page says "we will make all the necessary deductions based on the measurements you provide. Do not make your own deductions." Custom motorized shades are made to size and generally not returnable, so the remake policy is the real safety net: SelectBlinds' FIT Protection covers a remake within 90 days when the error is within 2 inches per side, 1 remake per product and 4 per household, with remake shipping charges applying; Graywind's Worry-Free Fit offers a free remake within 30 days for a discrepancy "within a reasonable range"; SmartWings states that customized products are "non-refundable and non-exchangeable unless defective." Policy text is perishable; the seller's page on the day you order binds. Run the numbers through the Measure and Mount Fit Checker, and if the trim is off limits, decide on the jamb or a mounting board before you pick the mount type. A retrofit kit adds one step: confirm its bracket lands on solid wood, not the plaster beside the jamb.