How to Install a Window with a Nailing Flange Part 1

If you are considering adding a window to your home, then you may be wondering whether to install a window with a nailing flange. These windows come with a strip of metal along all edges which is pierced and ready to take in the nails. These flanges help when placing the windows, although you may need a slightly smaller opening than with an ordinary window, as you will not have to shim the edges when you install a window. In the first part of this guide to installing a window with nailing flanges, you will learn how to place the window in the opening, how to add shims to the top and bottom of the opening, and how to remove the siding if required before fitting building paper to the sides.

NOTE: This article is part of a 2-part series. To move on to Part 2, click here.

Step 1 - Insert the Window

In order to install the window, you will need to have already created a basic opening in the side of the wall. This is known as a rough opening, and should be cut to the dimensions described in the window's instruction manual. You can leave the siding for now, although it may require cutting back later on. Place the window against the rough opening, and then slide it into the gap with assistance from a friend. At this point, the window may not fit exactly into the window, and you will need to add shims to the top and bottom in order to get the right angle for your window.

Step 2 - Add Shims

With your window in the opening, place a spirit level against the bottom edge of the window and place shims around the bottom until the spirit level is showing that the surface is level. Most spirit levels use a small viewing area with a bubble of liquid in the middle. Place your shims at the edges of the window until you can see the bubble in the middle of the viewing glass. You should then add supporting shims to the bottom window to ensure that it is supported. Repeat for the top edge to ensure that the areas are completely level.

Step 3 - Mark and Cut Siding

Once the window is correctly installed into the opening, you may find that you need to cut down the siding to accommodate the flanges. Take a piece of chalk, and mark around the edges of the flange, so you will be able to see if any siding is obstructing the insertion. Remove the window, and then take a small saw, and cut down the siding, leaving a thin layer of brickwork to which the flanges will be attached.

Step 4 - Add Builders Paper

You will then need to add builders paper to the edges of the windows. Do this by measuring the lengths of these edges with a tape measure and then marking the lengths needed on a sheet of builder's paper. Add a layer of caulk and then place your builders paper over the top. Add another layer of caulk, and leave to dry.