How to Use a Pulley to Lower a 4-by-8 from a Loft

Preparing the Lift

• 1

  Measure the length of the beam with a tape measure. Multiply the length of the lumber by 12. Multiply the result by its width and height in inches. Divide that result by 144. The answer is the number of board feet in the four-by-eight.

• 2

  Calculate the weight of the four-by-eight, based on its size and type of wood, using a lumber weight calculator. Use this information to select the size of the pulley and rope necessary to safely lower the four-by-eight. For example, if the four-by-eight is red oak and 26 feet long, it weighs about 333 lbs. Different woods and lengths affect the weight.

• 3

  Divide 333 by 2,000. Use a calculator; the result is 0.1665. Extract the square root of this result--the answer is 0.408. Divide the result by 0.75: the result is 0.544. Translated into inches, that means that the rope you should use is slightly more than 1/2 inch in diameter. Rounding up to the next common size of rope, use 3/4-inch rope.

• 4

  Multiply the diameter of the rope by three, the constant used to calculate pulley diameters when rigging a pulley with a fiber line rather than wire rope: three times 3/4 inch equals 2 1/4 inches. Rounded up (always round up for pulley sizes), this means a 3-inch pulley is required for the project.

• 5

  Attach the pulley in an area that's above the height of any obstruction you must lift the four-by-eight over. Plan to mount the pulley beyond the farthest extension of the loft to avoid conflicts with the loft while lowering the four-by-eight.

Making the Lift

• 6

  Run a stud finder across the ceiling to find a joist, past the edge of the loft, above the lower floor. Drive 3 1/2-inch wood screws through the mounting holes of the pulley and into the ceiling joist, using a drill. Pull one end of the lifting rope (equal in length to twice the distance from floor to ceiling) through the pulley.

• 7

  Make a loop in the rope 10 feet from the end in the loft. Wrap the end of the rope around the center of the four-by-eight twice. Pull 1/2 of the rope that peeks upward from beneath the lumber up, to form a loop.

• 8

  Push the end of the rope through the small loop around the back of the rope hanging before you and back into the small loop. Pull the end of the rope and the loop in opposite directions to tighten the knot.

• 9

  Cut two lengths of line (called tag lines), long enough to reach from floor to ceiling in the space where you're moving the four-by-eight. Tie one end of each piece onto the ends of the four-by-eight to maintain control the lumber as it's lowered from the loft.

• 10

  Have two friends above control the lift as you and other friends pull on the working end of the rope that comes from the pulley to the floor, to raise the four-by-eight above its location in the loft. Tell the people on the tag lines how to control the movement of the ends of the four-by-eight as you lower it to the floor by slowly playing out the rope you're holding.