How to Install an Aluminum Casement Window

What You'll Need
Window and all its components
Power drill with drill bits
Bubble level
Water seal gasket or adhesive backed aluminum tape
Nails and screws
Siding or shingles for exterior

An aluminum casement window is a type of window. A casement window is a window sash attached by hinges on a frame to allow it to open. What defines a casement window vs. other windows which open on hinges is that the hinges are always attached to the side of the frame, not the top or bottom. Casement windows are common in older buildings although they can be a nice replacement or addition to any building. Casement windows come in various materials and are opened by the use of a crank or by hand.  Below is step-by-step instruction to install an aluminum casement window.

We will begin with the assumption that there is already a hole in the wall where your window needs to be installed and that it has been measured properly and the correct window has been purchased. All necessary hardware, if not included with window, will need to be purchased as well: crank mechanism, hinges, screws, lock.

Step 1 –Make Opening Watertight

It is vital that your opening be watertight. You do not want any rain to work its way between the wall and the window. Working from the outside, use a water seal gasket or aluminum tape to seal the opening. Roll out the material, beginning first on the bottom sill. Fix it on top of the sill as well as under it, being sure to leave no gaps. Next do the sides, being sure it is sealed tightly. Extend out on the side and bottom as your new shingles will go over top of this. Make good corners, cutting and folding over excess. Finish with the top.

Step 2 –Level Opening

Use your bubble level on the bottom sill and verify that the wall opening is level. If not, use a small shim to raise one side until it reads as level.

Step 3 –Place Window in Opening

The new window is held in place with a what is called a nailing flange. This may not come already bent. If this is so, you will have to bend it to a 90 degree angle so that when the window is installed, the nailing flange is flush with the wall. Once it is bent, it is time to lift the window into the opening. 

With the aid of a helper, lift the window into the frame and set snugly. Be sure you shim hasn’t moved.

Step 4 –Nail the Window

Beginning at the top, hammer a nail into the center hole, then place a nail in every other hole. Check to see that your window is still level. If it is, continue placing nails in the remaining holes in the nailing flange.

Step 5 –Additional Water Seal

Over the top nailing flange, place more gasket or aluminum tape. This is help to insure that there is no leakage from the top.

Step 6 –Interior Installation

You will need to build out the casing. Once this is completed, you can install all the window hardware. Follow the manufacturer’s guidelines.

Step 7 –Finish Work

Your window is now installed and all that remains is the finish work. On the interior, you will need to hang molding and paint the casing and the molding as needed. On the exterior you will need to install a new sill and window frame. Be sure to caulk all openings to further guard against water leakage.

Finally, replace any shingles or siding that were removed.