Inspecting the Wall

• Install cornices on load-bearing walls whenever possible. If the window is not located on a load-bearing wall, you will need to locate the studs with a stud finder. Alternatively, you can use a ball-peen or other small hammer to tap gently on the wall. If the sound produced is hollow, there is no stud in the area. Keep tapping until you hear the hammer tap the stud.
  
  

Measuring for Cornices

• Measure the window with the tape measure, working from the outside edge of one window sill to the outside edge of the other sill. Build the face (or front) of the cornice to match this length.
  
  If you have a non-load-bearing wall, measure from one stud to the next, in order to determine the length that you should build the cornice. Heavier cornices should be attached solidly to studs. Another option is to choose lightweight building materials and attach the cornice directly to the window sill.
  
  Determine the depth of the cornice by measuring from the drapes to the wall. Take this measurement with the drapes open, measuring from the folds of the drapes. This will ensure that there will be enough room for the drapes to move freely once the cornice is in place.
  
  

Types of Wood

• Using lighter wood to build the cornice makes for easier installation.Wood Boards image by Towards Ithaca from Fotolia.com
  
  Choose pine, poplar or aspen to build cornices that you plan to paint or upholster. For painted cornices and covered cornices, fiberboard, oriented strand board (OSB) and particle board are lighter options, making these materials easier to install.
  
  For stained wood cornices you may choose hardwoods such as mahogany, oak, maple and cherry. Keep in mind, however, that heavy, dense wood products may cause difficulties when it comes to installation. You will need to be able to lift the cornice and keep it in place when attaching it to walls or studs. You will also need to use strong materials to attach the cornice to the wall, in order to keep it secured.
  
  

Purchasing Wood

• Make sure that boards have straight edges and sides.Stacked Boards image by Towards Ithaca from Fotolia.com
  
  Purchase wood based on the measurements of your window. Keep in mind that a cornice has four sides, a front, two sides and a top. The front should be slightly longer than the width of the window from sill to sill. The two sides will need to be deep enough to accommodate the movement of the drapes. The top will need to be equal to the depth and width of the face and sides.
  
  Before choosing wood, inspect the individual pieces for knots or other flaws. Also, check that pre-cut lumber has straight, smooth edges. This will make putting the cornice together much easier than if you were to use poorly cut pieces of lumber.
  
  

Cutting the Wood

• Use a circular or table-saw to cut the wood to the correct size.construction tools, saw image by Greg Pickens from Fotolia.com
  
  Choose a pattern for the cornice shape. The most common shapes for cornices are boxed, curved and scalloped. While boxed cornices are the easiest to build, scalloped and curved edges can add a more decorative touch to the room. If you select to make a scalloped edged or curved edged cornice, either trace the pattern free-hand onto the wood or make a template from cardboard and transfer the pattern this way.
  
  Use a circular-saw or table-saw to cut the wood to the appropriate length and width. If using patterns for the cornice, a jig-saw is the most appropriate saw for cutting out the details.
  
  

Assembling the Cornice

• Assemble the cornice by attaching the face to the sides. This can be done in several ways. Use wood glue along the joint. Firmly attach the two pieces with staples, nails or wood-screws. Once both sides are attached, secure the top of the cornice in the same way as the sides.
  
  

Finishing and Hanging the Cornice

• Cornices may be upholstered to match any room decor. If you choose to upholster, you may wish to use a layer of cotton batting beneath the fabric layer. Fabric can be attached using upholstery tacks or secured at the seams with fabric glue or tack.
  
  Apply wood stain and allow it to dry completely, before installing the cornice. If you choose to paint the cornice, it should be installed first, in order to prevent the painted surface from being marred during installation.
  
  Use a ledger to hang the cornice. Fasten the ledger to the wall studs, using 2 1/2-inch screws, spaced about 12 inches apart. Attach the cornice to the ledger, angling screws downward at 12-inch intervals.