Ordering

• From the inside of the house, measure the window from jamb to jamb. To find the window's width, measure from one side to the other. Take three sets of measurements from different areas of the window: the top, the middle and the bottom. To find the height, measure from the top to the bottom along the right side, the center and the left side. Use the smallest measurements when ordering your replacement windows. Never assume your windows are uniform in size: Take a separate set of measurements for every window in your home. As correct measurements are crucial to this process, double-check your figures before ordering new windows. Custom-made replacement windows can't be returned if you order the incorrect size.
  
  Before ordering new windows, examine your window frame carefully. If the wood is rotting or in bad condition, it will need to be replaced before new windows are installed, which might require the services of a professional installer. Order replacement windows, custom-made to your precise measurements, from home improvement or window specialty stores. Replacement windows come with either wood, vinyl, aluminum or composite frames. Vinyl replacement windows have become a popular choice for many homeowners because of their convenience and ease of installation.
  
  

Installation

• Remove the inside window stops--the guide rails that control the way a window opens and closes--and set them aside. Remove the inside sash, then slide the outside sash down and remove it as well. Discard any sash chains, cords or weights. Leave the exterior stops in place, as these will help keep the replacement windows in the right position during installation. Clean the window jambs and caulk any holes.
  
  Apply a small amount of caulk to the interior of the outside window stops. Fit the replacement window into the empty frame, using a carpenter's square to position it correctly. If the new window is narrower than the frame, either fill the gap with caulk or nail a slim strip of wood to the inside of the frame. Nail the inside window stops back into place, then caulk around the area where the stops and frame meet.
  
  Examine the window from the outside to make sure the shape of the new window matches the shape of the sill and to check for gaps. Replacement windows often come with an additional piece to cover any gap between the window and the sill, or the gap can be covered with a piece of wood. After this is done, the only task remaining is to enjoy your new windows.