egress window installation
First, make sure the window is actually certified to meet the code requirements for an egress window. The major window requirements are the clear opening (width and height) and the open square footage. Casement windows, even when cranked out fully, may obstruct the real CLEAR opening. Most certified windows have a sticker applied by the producer stating that the opening is compliant. The size of the opening is governed to allow entrance for a fire fighter with tanks to enter and fight the fire.
After that, the main thing is the height to the bottom of the CLEAR opening (not sill) and that is usually 44", but some jurisdictions have a 42" height to allow the exit by children.
Once you have established the location of the window location, the hole in the wall for a rough opening can be used to determine the space available to hold things up. A 3' long lintel to span over a window with a 2'-4" CLEAR opening sounds a little short for a loadbearing wall since there is not much left for bearing on the 12" concrete block wall.
Any reputable supplier of beams or lintels will be able to provide the information allowed on their product based on the loads you have determined for your application.
Last edited by concretemasonry; 03-11-2011 at 12:24 PM.