How to Drill a Microllam Beam

Microlam is a generic name for laminated veneer lumber.

Holes Between One and One and One-Half Inches in Diameter

Mark microlam before drilling it.Mark microlam before drilling it.
This composite wood is made of thin veneer sheets held together with glue. In microlam, the highest grade wood veneer strips make up the outer layers. The lowest grade wood veneer is in the innermost layers. Drilling disrupts the bond of the quality veneer and reduces its structural integrity. You can drill horizontal holes through the width of the microlam beam, but only in low-stress areas. Before you start drilling, map out the low-stress areas to guide your work.

Step 1

Lay the beam flat.

Step 2

Measure the length and width of the beam. Record those measurements.

Step 3

Draw a horizontal line near the top of the front face of the beam with the top quarter of the beam's width above it. For example, if the beam is 8 inches wide, draw a horizontal line on the front face of the beam with 2 inches of space above it all along its length.

Step 4

Measure in one-eighth of the beam's length in from the left side of the beam. Mark a vertical line from the top of the beam down to the bottom of the horizontal line you made in step three. Repeat on the right side of the beam. For example, if your beam is 8 feet long, you should have two 1-foot-long sections on either side of the beam. Mark these sections with a check mark to indicate that it is OK to drill in these two small areas.

Step 5

Draw a horizontal line near the bottom of the front face of the beam with the bottom quarter of the beam's width below it.

Step 6

Draw a vertical line on the left side of the face of the beam with one-quarter of the length of the beam to the left of it. Start the vertical line at the top horizontal line and down to the bottom horizontal line. Repeat the process on the right side of the beam. Draw a check mark on the rectangle made between the two horizontal lines. It is OK to drill holes in this area.

Step 7

Drill a hole in one of the three checked sections made in steps 1 through 6. The hole's diameter must be under 1 1/2 inch, or one-tenth of the beam's width, whichever diameter is smaller. Place the hole at least four hole-diameters from the nearest top and bottom beam edge and 8 hole-diameters from left and right edge of the beam. Measure hole-diameters from the nearest edge of the hole.

Step 8

Spray water-repellent sealer over each hole to seal it.

Holes Smaller than 1 Inch in Diameter

Step 1

Lay the beam flat.

Step 2

Measure the length and width of the beam. Record those measurements.

Step 3

Draw a horizontal line near the top of the front face of the beam with the top quarter of the beam's width above it. For example, if the beam is 8 inches wide, draw a horizontal line on the front face of the beam with 2 inches of space above it all along its length.

Step 4

Measure in one-eighth of the beam's length in from the left side of the beam. Mark a vertical line from the top of the beam down to the bottom of the horizontal line you made in step three. Repeat on the right side of the beam. For example, if your beam is 8 feet long you will have two 1-foot long sections on either side of the beam. Mark these sections to indicate that it is OK to drill in these two small areas.

Step 5

Draw a horizontal line near the bottom of the front face of the beam with the bottom quarter of the beam's width below it.

Step 6

Measure and mark the point 6 inches away from either side of the support beam or the location where the support beam will go. Extend the line between the top and bottom of the horizontal lines made in steps three and fie. Do not drill in these areas.

Step 7

Drill holes anywhere in the top two areas made in step four, and the central rectangle bordered by the top and bottom horizontal lines, excluding the 6-inch sections marked out in Step 6. Place each hole at least eight hole-diameters away from the top and bottom edge of the face of the beam and eight hole diameters from any neighboring holes. Use the diameter of the largest hole when measuring between two holes of different sizes. Drill no more than one hole per 5 feet of microlam beam length.

Step 8

Spray water-repellent sealer over each hole to seal it.

Things You Will Need

  • Measuring tape
  • Pencil
  • Straight edge
  • Level
  • Water-repellent sealer

Tips

  • The rules for holes 1 inch in diameter or smaller only apply if the beam is at least 7 1/4 inches wide. If the beam is more narrow, follow the rules for larger holes in section one.
  • Do not drill vertical holes in microlam beams.

About the Author

Based in Houston, Texas, Meg Butler is a professional farmer, house flipper and landscaper. When not busy learning about homes and appliances she's sharing that knowledge. Butler began blogging, editing and writing in 2000. Her work has appered in the "Houston Press" and several other publications. She has an A.A. in journalism and a B.A. in history from New York University.