Billy bookcases are a popular brand of freestanding bookcases available from IKEA. They come in a variety of colours and decorative options, such as glass panel doors and cabinet lighting, and can be made to fit around corners. They are constructed using sturdy materials that don't easily warp, so they're ideal if you want bookcases that appear as if they're a part of the home's architecture. Making Billy bookcases look built-in takes a few simple steps and some planning.
Determine the location for your Billy bookcases and buy the right amount of units and extensions needed to fill the space. Make sure you know in advance if you are planning to wrap the bookcases around a corner because you'll need special hardware from IKEA for that.
Remove any existing skirting trim and quarter round from the floor and wall in the location where you plan to put the bookcases. Use the claw end of a hammer to do this.
Assemble your bookcases and set them up against the wall. Use the wall anchors provided in your kits to secure the bookshelves to the wall and to each other.
Cut the 5 by 10 cm (2 by 4 inch) wood the same length as the entire bookcase wall unit and nail them to the ceiling parallel to the front edge of the book shelves. This will enable you to attach the crown moulding to the wood on the ceiling without the crown moulding being flush to the wall.
Attach the crown moulding over the space between the top of the bookcase and the wood strips using a nail gun. Make sure the nails go into the moulding at a 45-degree angle and grab the wood ceiling strips.
Use caulking to fill any space left between the ceiling and the top edge of the moulding. Some ceilings aren't completely flat, so this step gives the entire unit a finished look.
Attach skirting trim along the bottom of the bookcase unit with the nail gun. Attach quarter round to the bottom edge of the baseboard trim; use liquid nails if you want to avoid nail holes. Finish all other exposed edges where the bookcases come into contact with the walls with the remaining quarter round.
Purchase moulding that is the same colour as your Billy bookcase or that can be stained or painted to match.