I'm planning to install a code compiant egress window (28" x 46" overall) in my basement in a load bearing wall of 12" cinderblocks. I plan to use a 3' long header made up of 3 31/2" x 51/2" timberstrand engineered wood beams. There will two courses of cinderblock above the header. My question is, has anybody had any experience using timberstrand or other engineered wood products in this type of application or would 2x 10s or 12s dimensional lumber be safer? According to timberstrands tables one 31/2 by 51/2 3' beam would carry my loads (less than 1200plf). I can't find any reviews anywhere about the claims of engineered wood products!
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 11:24 AM.