A Comprehensive Look Into Construction of Wood Exterior Blinds and Shutters With a Touch of History
The preservation of historic buildings has both historical and sensible value. Older buildings carry the stories of our shared past and capture the nostalgia of a bygone era. But they also have practical worth in terms of the quality of materials used in their construction; rare hardwoods like heart pine or wood from virgin forests that have long since been destroyed.
Communities are now coming to realize not only the significance but also the usefulness of these older buildings for neighborhood revitalization as they are restored and pressed back into service as new homes or for business use.
Preservation of buildings takes a lot of money, effort, and care. Restoring an older building also takes attention to detail and a commitment to getting each and every feature historically accurate.
Over the past 35 years, my passion has grown exponentially for making historically correct blinds and shutters employing hinging applications used in the past.
Cobblestone Millworks has been involved in the restoration of historic properties including the Appomattox Courthouse National Historic Park, Graceland Mansion, Little White House, the Lighthouse at St. Simons Island, and Booker T. Washington State Park, to name a few.
The challenges we encounter on a daily basis involving the process of custom and historical matching, design, proper use of material, exceeding structural integrities and warranties, hardware applications, and proper millwork terminology have given us a wealth of knowledge on the subject.
In this article, we offer our expertise to architects, purchasing agents, homeowners, and our customers to help them understand the process of creating historical blinds and shutters while restoring an older building to its former glory.
Radius-fixed louvers are the most common style of louvered blinds found today. These fixed slotted louvers became common in the early 1920s and took the place of moveable louvers as blinds became less functional in use. Hybrid styles of shutters which included a mix of panels and louvers in different combinations also become commonplace.
Typically, ¼” to ½” in thickness, widths can vary from 1 1/8” to 2 ¼” wide. The radius or bullnose will always be equal to the thickness of the slat. Very easily manufactured either on a shaper or with a high-speed molder for volume. This radius slat is assembled into the frame having an identical groove plowed to the depth of 3/8” into each side stile. The length of the slat is cut approximately 1/8” shorter than the total span allowing for relief due to expansion and contraction. The two ends of each louver are chamfered for guidance to aid in the installation. Installation can be accomplished manually or by automation. The side stiles are plowed using louver slotting machines and computerized routers. Contrary to popular belief, the slats are not glued in place.
Types of Shutters
Board and batten design consist of a layer of vertical boards held together by horizontal battens with optional diagonal braces that are considered shutters. This style was referred to as a plank shutter in the early 16th century and was used in less refined structures such as cottages, stables, barns, and workers’ cottages. Historically, board and batten shutters would have been used for privacy or security. Boards would have been butt and nailed together on battens since screws were handmade, too expensive, and less effective than modern wood screws during those early years. More modern patterns were later introduced by leaving spaces between boards or by machining a tongue and groove detail on the inside edges. This pattern is more commonly referred to as reverse board and batten shutter. This pattern will always be much more stable since each board is locked together. A nice additional touch is to bevel or chamfer the edges of the battens and braces. Decorative metal clavos can be added for a rustic hammered nail look. Board and batten styles were favored in French locales like New Orleans.
The simplest type of shutter is constructed with flat panels. This style began to appear in the late 17th century in Beaufort, South Carolina. This design eliminated the warping that might have occurred with plank shutters. Flat panels look fine especially with a simple cutout motif or with an added low profile molding or stop. Many of the standard cutters today only offer a thin rabbet or plow down the center and restrict the thickness to a ½ inch. This is not sufficient for a solid panel. A wooden flat panel shutter should consist of at least a ¾” thick stock, especially in wider widths.
Raised panel shutters are the most common type. Raised panel cutters are offered with a number of different style profiles for a ¾” thick material. Most manufacturers offer only one standard profile due to mass production. That is acceptable if you are not trying to replicate or match existing shutters. We also keep our standard profiles with our higher-volume product lines but maintain an expensive inventory of 12 of the most common profiles which encompass most raised panel profiles used in the manufacture of shutters today. This also allows us to keep our customer’s costs down when we take on replication projects. Panels can be single-sided or double-sided raised. If you are not hinging your shutters, there is no need to raise both sides.
When the panels are assembled in the frame they must be machined so that they float freely within the frame to allow for any dimensional changes due to fluctuations in climate. If you also restrict the panels from movement with glue, brad nails, or caulk you can cause the panels to split vertically. This is one reason why I am not a big proponent of adding high-profile moldings or appliqués to flat panels. While they look attractive, if they are not properly installed, they can restrict movement allowing moisture to be added and they can become unattached over time. On Colonial period homes (1895-1940), raised panel shutters are seeing a revitalization.
Panel Shutter Cutouts
Our approach to this topic is a simple one. We offer our own library of templated designs such as animals, flowers, trees, and other objects from which the homeowner can choose. Our new modern computer numerical control (CNC) machinery and software allow the customer to simply pick a picture, sketch, or drawing of their choosing and forward it to our computer-aided design (CAD) department for replication. We then import that PDF, PIC, or DXF file into our CAD/CAM program before sizing the cutout based on your shutter sizes. It is important to remember that shutter widths will vary the size of each individual cutout. There is one fee regardless of complexity and from there we reduce the price based on quantity. We maintain your cutout design on file in the event you need additional shutters in the future. Panel shutter cutouts were only just introduced during the 20th century to personalize your home.
This is a simple process of applying faux lines with a router typically using a ½” v-groove router bit running vertically on a raised or flat panel to simulate the desired width board. This process should be applied to both sides of the panels to prevent cupping and splitting while balancing the panel. It is a very attractive addition and one of my personal favorites.
Different Methods of Joinery
The main consideration for choosing the correct method of joinery is to design the joint to maintain the frame (carcass) while keeping its shape and maintaining a square. The following types of joinery methods can be used on shutters and blinds.
Glues and Epoxies
The term adhesives include any substance having the ability to hold two materials together by surface attachment. Glues are the most common adhesives for bonding wood. Choosing glue is not easy. We must take into account factors such as the type of wood, temperature, humidity, type of joinery being glued, working properties of the glue, and finally cost. No adhesive will perform to satisfaction if not used properly. There are several types of special-purpose adhesives such as hot melt, construction adhesives, and contact cement which we rarely use in the manufacturing of shutters and blinds. The following types of glues are commonly used in bonding wood.
For most of our softwood applications like western red cedar, we use a modified PVA (polyvinyl) acetate 1-part waterproof type of adhesive. It is easy to apply, quick-drying, nonstaining, and less expensive than epoxies.
Machining is also critical when gluing parts. Uniform thickness and flatness are always necessary to obtain proper adhesion. When exceeding the standard girth requirements in louver blinds, and especially with the excessive weight of raised panel shutters, we substitute the previously mentioned epoxy resin to ensure the products will not separate when hinged.
Log Sawing Techniques
Quality comes from the cutting. A log can be sawn in different ways to make the best use of the wood and to obtain the best pieces for a particular purpose. The most common cuts are:
Through and through sawn or slab sawing is sliced from end to end (axis) in line with the grain. This type of cut can produce a few boards near the center of the log that can contain pith. When recut or radial sliced, it can yield two quartersawn boards. Waste is minimized, but boards are prone to warping.
Flat-sawn is a tangential slice from a log mostly tangent to the annual rings. This method avoids including the unstable heart of the tree which is box cut out and discarded. When drying, movement will mostly come from the width of the board which is not desirable.
Traditional quarter sawn material is what we primarily use in the construction of our shutters and blinds. It is a radial slice of a log perpendicular to the face between 60 and 90 degrees.
Quartersawn lumber takes longer to dry than flat sawn. Moisture is released from the edges of the board rather than the face when drying. This type of sawing technique can also be referred to as vertical grain. This cut produces a separate grade that can be sold at a much higher premium and produces boards that are dimensionally stable and less apt to warp or twist when machined.
It is both challenging and meaningful to carry a replication project from design to completion. The complexity and detail that goes into each project, including historical matching, design, proper millwork, and correct hardware application, can be difficult.
However, our experience helps us to build even the least expensive product lines with the highest quality and we are able to achieve a blend of customization with standardization in our product lines. We enjoy helping our customers through all stages of a difficult project, offering AutoCAD line drawings for pre-approval to minimize mistakes on both ends.
We are proud of the contributions we have made to historic preservation projects throughout the country, many of which we never get to see in person. It is enough to know that somewhere there is a historically accurate building that we helped to preserve for future generations and giving it new life and purpose.