Small horizontal holes are permitted only within the designated middle half span and center vertical zone of glulam beams subjected to uniform loads. Hole diameters must not exceed one and one-half inches or one-tenth of the beam depth, whichever is smaller, with round holes exclusively allowed and no penetrations permitted in cantilevers or in spans less than ten times the beam depth. The maximum number of holes in the designated zone is restricted to one hole per five feet of beam length, and the minimum clear distance between adjacent holes must be at least eight times the diameter of the largest hole.
NOTES 1. SMALL HORIZONTAL HOLES ARE PERMITTED IN "HOLE ZONE" IN BEAMS SUBJECT TO UNIFORM LOADS ONLY. 2. HOLE DIAMETER SHALL NOT EXCEED 1 1 2 " OR 1 10 x BEAM DEPTH, WHICHEVER IS SMALLER. SEE TABLE FOR MAXIMUM HOLE DIAMETER IN "HOLE ZONE". 3. HOLES ARE NOT PERMITTED IN BEAMS WHERE SPAN IS LESS THAN 10*D. SEE TABLE FOR MINIMUM SPAN. 4. MAXIMUM NUMBER OF HOLES IN ZONE 1 SHALL NOT EXCEED 1 HOLE PER 5 FT BEAM LENGTH. 5. ROUND HOLES ONLY. SEE TABLE FOR MAXIMUM HOLE DIAMETER. 6. NO HOLES ARE PERMISSIBLE IN CANTILEVERS. 7. MINIMUM CLEAR DISTANCE BETWEEN ADJACENT HOLES SHALL BE 8x THE DIAMETER OF THE LARGEST HOLE IN THE BEAM. MIDDLE 1 2 SPAN SEE NOTES 3 & 4 GLB "HOLE ZONE" SEE NOTE 7 D SPAN BEAM DEPTH SMALL HOLES IN GLULAM BEAMS MAXIMUM HOLE DIAMETER (IN HOLE ZONE) 12"-13 1 2 " 1 1 8 " 15"-24" 7 1 2 "-10 1 2 " 3 4 " 1 1 2 " 14 D 14 D 14 SPAN 14 SPAN
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