In new construction, I rarely use them, preferring to go with an engineered wood section instead. So, if you have a 1/4' thick flitch plate, you have a net effective area of 2.03xAwood with an allowable stress of around 57 of LVL stress. In reno work, I have encountered the condition where I need to face mount a flitch beam to existing construction, which goes back to my point of using only the wood to transfer shear. Incidentally, a flitch plate will reduce the allowable bending stress (but not the total allowable moment) of LVL framing, because the effective Fb of steel (Fy/1.67Iw/Is) is lower than the Fb of the LVL. That said, I typically only use flitch beams in renovation work, where we are dealing with existing conditions that somehow limit the use of deeper sections. If beam span is 16 feet in length, then their depth (16 × 12) ÷ 20 approx 10 inches and width is 10/3 approx 4. As per LVL span rule of thumb, the depth of the LVL beam should be 1/20th of span in inches and their width is 1/3 to 1/4 of the depth. Beyond 2x, I figure that it won't work, and look to increase the wood beam size. What size lvl beam do i need to span 16 feet.

Here is an article describing the approach to design flitch plate beam, where both the wood and steel capacities are used in the calculation.ĭoes anyone have a rule of thumb on how much extra capacity they can achieve using flitch plates, versus the wood section alone? I usually figure 1.5x is safe, and may be able to go up to 2x. If your support is small, say 4x4 post, and your beam shallow, you may not be able to achieve the required load transfer. Make sure you have adequate number of bolts over the support to transfer all the shear from the steel to the wood. I would agree with that, where your flitch beam extends over the support.

Lvl flitch beam span table