Over time a loft can become unstable or wobbly. You may avoid these types of issues with the help of a friend during assembly.
Find the Studs
Viewing your loft structure, look for studs and areas where you can set support beams up. Use your stud locator to find the best places to install your support beams. If the loft is sagging, use temporary metal support beams to lift the flooring up enough to work. Once you have located the studs where you will secure your support beams, and you have taken the measurements from floor to ceiling under your loft floor, you are ready to prepare the support beams for installation.
Prepare the Support Beams
Each vertical support beam for your loft support will need to have the 3-inch bores into the wood to leave 1 inch of wood in the bottom of the holes. You'll use these holes to screw the vertical supports into the existing wall studs. You can deduct the width of your crossbeams from your ceiling-to-floor measurement to give them room to fit at the top, between your support beam and the underside of the loft floor. For example you would deduct 4 inches for the 4-inch beams, and you would deduct 6 inches if you're using 6-inch cross support beams. If you are a more advanced carpenter, you can also use a skill saw and dovetail or joint the wood where the cross beam and support beam come together.
Install the Vertical Support Beams
Once the verticals are prepared, go ahead and put one in place at a time; secure them into place with your wood screws by using the pre-bored 3-inch holes as your guide. Secure the first vertical support securely into place, and then put one end of your crossbeam into place at the top, with the other end touching the floor. Once the first end is in place, use your other support beam on the other end and raise it into the air. It is good to have a second person to help with this part of the project.
This method of raising the crossbeam is more effective if you have jointed the ends of your beams. Use your rubber mallet to lightly thump the beams so that they are even and straight. You can also use a level to check the balance of your loft supports as you go.
Secure the Crossbeam
Once you have both vertical supports in place below the loft, and the crossbeam secured above them, you can let down the temporary supports if you were using any. Then take your bore bit and drill a hole on each side of the crossbeam ends at 45 degrees. Put one on either side, right above the vertical support in the direction of the wall. Run screws through the ends of the crossbeam, and into the wall stud.