How to Build a Tiny House – Part 11: Installing Windows

Installing windows in your tiny house is made simple with these illustrated instructions.

January 2015

By the Editors of Skills Institute Press

Backyard Sheds and Tiny Houses Book Cover

Good things do come in small packages. Just ask internationally recognized small living expert, Jay Shafer. Ranging in size from 100 to 120 square feet, Jay Shafer's DIY Book of Backyard Sheds & Tiny Houses (Skills Institute Press LLC, 2013) features beautiful small houses can be used as guest cottages, art or writing studios, home offices, craft workshops, vacation retreats or a full-time residence. Whatever your building goal, this book will teach you how to plan and build your structure from the ground up. The following excerpt from chapter four, "How to Build a Tiny House," shows you how to install windows.

You can purchase this book from the GRIT store: Jay Shafer’s DIY Book of Backyard Sheds & Tiny Houses.

Looking for other steps? Check them out in How to Build a Tiny House.

Installing a Window

Although it is possible to replace damaged sashes in a window with a sound frame, in some cases you will need to install a new window. Factory-made windows are generally prehungthey include both the sashes that hold the panes of glass and the jambs that make up the window frame.

Choosing a Window: Prehung windows are available in a variety of styles. The most common is the traditional doublehung window in which two sashes slide up and down within the jambs (below). When buying a window, consider its insulating properties, which can be affected by the jamb material and kind of glass in the unit.

Purchase a window that is about 1/2 inch smaller on all sides than its rough opening to allow for shims to level the unit and for insulation. (If you are framing a new rough opening, choose the window first, then size the opening to accommodate the window.)

Installing the Unit: To install a woodframe window, nail the jambs to the rough framing through wood shims (opposite); aluminum-and vinyl-frame windows are generally fastened to the outside of the house through a nailing flange around the perimeter of the window. Once the unit is secured in place, insulate the spaces around the jambs with fiberglass or, preferably, a low-expanding foam.

 Tools and Materials for Installing Windows

Fitting A Double-Hung Unit

1. Positioning the Window.

For a new opening in a wall with wood or vinyl siding, buy a prefabricated drip cap and slip it into place between the siding and the building paper (inset).

Have a helper outside the house set the window in place so it is centered in the opening and the top brickmold fits up under the drip cap (right).

While you hold the window steady from inside, have the helper tack one corner of the top brickmold to the roughopening header with a 3 1/4-inch galvanized finishing nail.

Installing the Window 

Positioning the Window 
Leveling and Centering the Window


2. Leveling and Centering the Window.

Inside, clamp a carpenter’s level to the under-side of the head jamb.

While the helper steadies the window from outside, insert shims between the side jambs and studs at the top of the rough opening.

Holding up one corner of the window, slip a shim between the window horn and the rough sill (left). Add a shim under the other horn. Insert additional shims under the horns, as needed, to level the window.

Have your helper nail the other top corner of the brickmold to the header.

Insert shims between the side jambs and the studs at the middle and bottom of the window, being careful not to bow the jambs.

3. Nailing the Window in Place.

Drive a 3 1/2-inch finishing nail through the side jamb and shims into the stud at each shim location (below). Score the shims along the window jambs with a utility knife, then break them off flush with the jambs. Outside, nail the brick mold to the rough frame every 12 inches with 3 1/4-inch galvanized finishing nails. Pull the drip cap down tightly against the edge of the head brickmold. With a nail set, sink all the nails.

 Nailing the Window in Place

4. Insulating With Foam.

Fill the space between the window jambs and the framing with expanding foam insulation, working from bottom to top when filling the gaps around the sides of the window (above). Use the product sparingly—too much of it can cause the jambs to bow inward when the foam expands.
 Insulating With Foam

For further instructions, see How to Build a Tiny House.

Reprinted with permission from Jay Schafer's DIY Book of Backyard Sheds & Tiny Houses: Build Your Own Guest Cottage, Writing Studio, Home Office, Craft Workshop, or Personal Retreat by Jay Schafer and published by Skills Institute Press LLC and Four Lights Tiny House Company, 2013.Buy this book from our store: Jay Shafer’s DIY Book of Backyard Sheds & Tiny Houses.

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