A lintel is the horizontal beam put across an opening for a door or window in a wall to support and divert the weight of the structure above, around the opening in the wall and into the foundation and the ground. The lintel must be of sufficient strength to support the wall above it and prevent collapse.
Lintels may be made of many materials; steel, reinforced concrete or solid stone are most common. Steel is the thinnest and strongest. The process of making a lintel opening in an existing concrete wall requires some masonry skill and a few specialized tools.
Things needed: lintel board, pencil, mortise machine, sanding pad.
- Center the lintel board over the top ends of the side window posts. The lintel must be aligned the way you want it to appear once installed.
- Mark the location of the tenons on the top ends of the side window posts onto the bottom side of the lintel board with a pencil.
- Place the lintel board on the table of a mortise machine with the bottom side up so that you can see the pencil marks. The marks indicate where the mortises (A mortise is a slot cut through a piece of wood) need to be cut in the lintel board.
- ·Line up the mortise chisel with the pencil marks and pull down on the handle to cut through the wood. Make as many passes with the mortise machine as needed to complete the mortise on each end of the lintel.
- Sand the lintel on all sides with a fine-grit sanding pad. Align the mortises in the lintel over the tenons on the ends of the side posts and slide the lintel over the side posts.
Culled from eHow