Louvered Interior Shutters

By Derek Richmond April 23, 2024

Historic style meets modern utility

Custom interior shutters offer more style than Venetian or vertical blinds, and let in more light than curtains. Rotate the movable louvers to direct sunlight where you want it. Or open the double bifold panel to really let the outside in. My windows are tall, so I split the space into a top and bottom half; I can open the top panels for illumination while keeping the bottom panels closed for privacy. And the bifold setup means they take up surprisingly little space inside even the largest windows. Best of all, with a little bit of math (see Making a panel plan, below), they can be custom-fit to your windows.

While sometimes called plantation shutters because of their popularity in antebellum estates of the American South, that name carries a troubled legacy, and anyway doesn’t tell the shutters’ full story. Interior shutters actually originated in Ancient Greece, where — made of marble — they served to keep coastal weather out of the un-glassed windows. As the shutters became more popular, wood replaced marble, allowing for movable louvers. Their fashion spread through Europe and they were eventually brought to the Americas by Spaniards. Lacking access to a suitable marble quarry, I built mine from poplar, painted white to match my window trim. Pine, basswood, or paulownia would work just as well; or use cherry or oak stained to match your home’s existing trim.

Love your louvers

Each panel consists of a bridle-jointed frame filled with 2-1/2" wide louvers. The louvers pivot on two types of specialized pins. Most of the pins allow the louvers to spin freely, while three or four sets of tension pins hold them in the desired orientation. A side-mounted control arm rotates all the louvers in a given panel at once. A router bit makes it easy to shape the many (or in my case many, many, many) louvers, and a drill press jig makes boring their ends for those pins easy. See the Buyers Guide (click here for PDF download) for sources and part numbers of those special components. If your windows aren’t deep enough for the panels to fit inside, add mounting strips to frame your shutters (see "Shutter mounting", below).

Order of Work

Cut bridle joint in frame
Drill stiles for louver pins
Drill louvers for pins
Rout louvers to shape
Create control rod
Assemble panels
Install in windows

Making a panel plan

First, determine the area to be covered by the shutters — either the inside of the window opening, or the inside of the mounting frame. For full-height shutters, the panel height is the shutter opening height minus 1⁄4" (for clearance). For shutters with upper and lower panels, divide the result by 2. The individual panel width is the total shutter opening width divided by the number of panels, less 3⁄16" (again, for clearance).

Determine the number of louvers by subtracting twice your desired rail width from the panel height, and divide by 2. Round to the nearest whole number. Then modify the width of the rails to make the opening in the panel frame equal to this whole number.

Prepare the frame

After determining your shutter panel sizes, mill the rails and stiles. Then rout a bead on one edge of a face of each stile. Cut the bridal joints at the table saw using a tenoning jig (OnlineEXTRA: click here to see a shopmade option) in conjunction with a blade with a flat-top grind. To compensate for the pieces’ different thicknesses, the mortises in the stiles are offset toward the stiles’ outside face while the tenons on the rails are centered on the rails’ thickness. After cutting the tenons, use a miter fence and dado blade to reduce the tenons’ width to match the 3" depth of the mortises. Then chamfer the inside edges of the rails at the router table so the louvers can fully open and close. Drill the beaded edge of the stiles to accept the shutter pins (see Buyers Guide). Locate the first pin hole on each stile. Then, using a fence with marks every two inches, drill holes for the shutter pins by advancing the initial layout mark along the fence for each consecutive hole.

Mortise the stiles. With the blade height set to 3", guide the stile vertically past the blade while clamped to a tenoning jig. Flip it end for end to cut the opposite end, keeping the same face against the jig. Then adjust the fence to widen the mortise to 1⁄4". A backer board helps prevent tearout.

Shoulders first. Cut the tenons’ shoulders on the ends of the rails at the table saw using a miter gauge. Either attach a stop block to your miter fence or use a standoff block on your rip fence to position the cuts.

Cheeks next. With the shoulders cut, clamp the rails in a tenoning jig to make the two cheek cuts, flipping end for end and side to side to produce centered tenons.

Drill for the pins. Bore the 1⁄4"-dia., 3⁄8" deep pin holes into the beaded edge of each stile, aligning the initial layout mark with the 2" marks on the fence as you go.

Create the louvers and control arm

Mill the louvers to 1/2 × 2-1/2" and crosscut to 3/16" short of your frame opening width. Cut a few extra blanks to use for set up and as spares. Measure and mark the center of the end of one louver blank and use it to set up for drilling the pin holes in the ends of all the louvers. Dial in the louvers’ shape with setup stock, using a beveled spacer for added support as shown. For my setup, a 10° bevel ripped off the corner of some 3/4"-thick milled scrap served nicely. This operation requires a 1-1/2-dia., 2" tall moulding bit, and bits this large typically call for slow speeds. But I found that 22,000 rpm is safe in this instance and produces a smooth cut that requires little sanding. Mill the control arm to size, leaving it an inch longer than the center-to-center distance between the topmost and lowest louvers. Rout a bullnose profile on one edge of the control arms. On the opposite edge, drill holes for the screw eyes (see Buyers Guide) that will attach it to the louvers.

Drill the louvers. Use a pair of vertical fences attached to an auxiliary table to orient and hold the louvers, then bore a 9⁄64"-dia.× 3⁄4" deep hole in both ends of every louver.

Rout the louvers. Locate the router bit and fence to leave a small flat on each face of the louvers when all four corners are routed. Adhere a spacer to the fence with double-faced tape to catch the otherwise wobbly piece on the outfeed side of the cut.

Rout the control arm. Use featherboards on the fence and table to safely rout the bullnose profile into the front edge of each control arm. A 1⁄4"-radius roundover bit creates a clean and elegant look.

Drill for the screw eyes. Bore 1⁄16"-dia. holes 1⁄2" deep, spacing them every two inches. The marked fence used to bore holes in the stiles doubles as a drilling guide for the control arms, though I had to rip mine down a bit to clear the chuck.

Finish and assemble

Plan your finishing process carefully. If you’ve only got one or two panels, mask off the mortise and tenon joinery, then finish the louvers and frame parts separately before assembling and touching up; I built eight panels, so it made more sense to fully assemble them before spraying. Either way, when you glue up, install the shutter pins in the louvers. Then assemble the frame around the louvers. Twist the screw eyes into their pre-drilled holes, oriented with their loops parallel to the length of the control rod. Attach the control rod to the louvers before installing the panels in your windows. See the Shutter mounting sidebar (below) for tips on installation options.

Install shutter pins. Press or tap the pins into the ends of each louver until the shoulders butt against the louver ends. Install tension pins in 3 or 4 louvers per panel to help the shutter set maintain its orientation.

Install the control arm. Pre-drill the front edge of each louver for screws then slip a round-head screw through a screw eye installed on the control arm, and drive it into the end of the corresponding louver. Continue down the panel, connecting all the louvers to the arm, allowing them to move in unison.

Shutter mounting

With so many different window configurations, I can’t address them all here, but in general you have two options. If your windows are deeply set, you may be able to install the shutters directly in the window well, attaching the hinges to the window’s jambs. For shutters with 21⁄2" louvers, you’ll need at least 13⁄4" of clearance behind the panels to allow the louvers to open properly. You may still need to add a mounting strip to the jambs so the shutters can swing past the casing.

If your windows don’t have the required depth, you can add mounting strips to the wall surrounding the window to screw the hinges to. Either remove the window casing and attach the mounting strips in its place, or it may be possible to attach the strips directly to the casing. No matter what, figure out your mounting system before making the shutters.