Flitch beams depth

[Beau]

Help >> Flitch beams, mentions
"D, being the depth of the flanking timber (D-25 or similar is acceptable"

What does D-25 mean, is this depth minus 25mm? %? other meaning?

[Tony Bryer]

Yes, D is the depth [height] of the flanking timbers in mm, so if you've entered a timber depth of 220mm, D-25 is evaluated as 195mm The normal practice for flitch beams is to use a reduced depth plate (typically D-20 or D-25) so as to allow for any timber shrinkage. If you ask the program to calculate the required depth (by putting a ? in the depth column), as the program steps through the timber depth list, the plate depth automatically increases accordingly. If you know the size or are checking an existing structure you can just enter the plate height in millimetres, e.g 165 or 195.