Building a Turret from the Ground Up
The challenge: turrets are round, wood is straight.
When my partner, Jim Himel, bought our house in 1986, there was a big square addition to the second floor on the front of the house over the porch. While we liked the extra space, which functioned as a spare room/closet off the master bedroom, and imagined that one day it would serve as the master bath, we both felt the balance and lines of the addition were all wrong for the house.
Jim is an urban forester and environmental impact consultant by training and livelihood, but his true calling is tinkering. He had always imagined replacing the addition with a classic Victorian turret. However, in truth, his dream was less about making the house authentically Victorian and more about the challenge of constructing something round. Our friend, local architect Rob Brennan, suggested that we drive around Catonsville, taking stock of our options for turret design, height, and roof pitch. From there, Jim hired a carpenter and the two of them spent five months from August through January of 2009 building a turret.
First, they curved the sides of the original addition. Then they built a second story and a roof as two separate 'stages' in our driveway. Having parts of your house in the circular driveway is interesting and also allowed those who regularly walked or ran by to watch the progress. The construction also elicited many funny comments from people; the best question, asked more than once after the second stage was painted, was "How did you get it to match so well?" like we had ordered it from a catalogue and were so lucky to have found the right color! The last step was to bring in a crane to lift each stage and lower it into place on our house. The six month evolution had garnered enough fans that we posted a sign to broadcast the date and time of the turret lift, and we had a cheering section of about 25 people.
So, for anyone who does any home improvement carpentry, the challenge was clear: turrets are round, wood is straight. Jim began with a system that made me nervous in its simplicity. He took a string, a nail, and a crayon, and he drew circles onto plywood, creating circular plates which together made a 10 foot diameter circle. The plates were six inches across, forming the tops and bottoms of the walls. The studs ran between them, placed at twelve inches, rather than the normal sixteen inches, to accommodate the curve.
The skin of the walls was plywood, but only 3/8th inch thickness, in two layers. At that thickness, the plywood will bend in one direction. The layers were glued and screwed.
Other complications of a round structure showed up. The top and bottom of the window, the transom and sill both needed to be cut like a bow, curved on the outside edge and straight on the inside. Also, the boards for the molding at the joints of the stages had to be notched on the back side so that they would bend.
People look at our new turret and ask, "How strong is it?" Jim smiles and says, "Look, it has the same aerodynamics as a rocket ship. The wind just blows around it." And it hasn't lifted off yet.