We install windows at Tiny Green Cabins using the following steps for all of our tiny houses.
Tools Needed: Hammer, caulk gun, slap stapler, level, tape measure, utility knife, work gloves
Materials needed: Butyl Caulk, Dupont Flex Wrap, Dupont Straight Tape 4″ wide, Shims, Great Stuff Window spray expanding foam
Step 1; After the Tyvek house wrap has been installed and wrapped into each of the windows opening, cut
the Tyvek house wrap at the window rough opening top corner diagonally about 4″ upward and away from the window and tack back.
Step 2; Cut the Dupont Flex Wrap 12″ to 16″ longer than the window sill. Peel off the paper backer centering the Flex Wrap in the opening and full width of the sill. Press into place across the bottom and up the sides of the window – minimum up each window side is 6″.
Step 3; Peel the paper off the back of the flex wrap hanging outside the window and starting at each window corner, pull the corners outward and stretch while adhering it to the walls, then pull and press the rest of flex wrap into place.
Step 4; Using the shims, lay a shim at each window sill corner for creating a space to insulate used in step 10
Step 5; Caulk up the sides of the window frame, across the top of the window rough opening and down the other side to the sill. Warning, DO NOT CAULK ACROSS THE BOTTOM OR WINDOW SILL – EVER
Step 6; Insert the window into the rough opening, center the window on the opening, and nail at one top corner of the window flange. Level the window and after leveling nail the other top window corner.
Step 7; Plumb the window sides Tip: Square the window and check the reveal spaces where the window meets the window jamb. To square, using a tape measure, check the measurements diagonally from each corner to the opposite corner – they should be equal. Also check the window edges from other features of the wall, such as wall corners or fascias to make sure things are set correctly. On a tiny house, since other features are close to the window, this is a check that everything is spaced correctly. After this check nail the window in place and around the window perimeter, nailing through every other hole in the flange.
Step 8; Install the corner flaps at each corner of the window.
Step 9; Cut the butyl tape for each side of the window and across the window head. Each piece should be cut 8″ to 12″ longer than the window. Install each side, and then install the top piece of Butyl tape.
Step 10; Pull the Tyvek that was tacked out of the way, fold it down, and tack in place, cutting just short of the window head. Tape to the butyl tape and Tyvek together to seal them tight.
Step 10; insulate the window jambs cavity to wall opening. We recommend Great Stuff as the expanding foam seals the cavity better than a stuffed fiberglass can. Plus the foam does not allow mold to grow if the window leaks.
Here a good video that follows our best practices