The floor joist are now installed. The next step that we will take is to install the sub flooring. The sub flooring consist of 3/4 inch 4ft x 8ft sheets of plywood. What ever you do please DO NOT CUT CORNERS while installing the sub flooring. there are alot of grades and brands of plywood on the market. I personally prefer vantek plywood above all the others. No matter what you are going to use for the finish flooring DO NOT USE 1/2 inch plywood you will have problem.
The importance of nailing your sub flooring correctly will mean the difference between a squeak and a quiet floor. My personal opinion is to screw the sob flooring down this will allow the highest quality possible. However if you decide to nail the plywood down use 8d nails. The nailing pattern that is recommended is 3 inches apart on the seams and 4 to 6 inches on all other joist located at 16 inches on center.
The sub flooring should be glued at every floor joist with construction adhesive. The purpose of applying construction adhesive is to help insure that you will have a quiet floor and a stronger flooring. The use of construction adhesive is code in most counties the general rule is a 1/2 inch bead of construction adhesive down the center of the floor joist. When you lay the sub flooring in place the construction adhesive will spread across the floor joist applying evenly under the weight. This process will secure the flooring with great strength.
The process for laying your sub flooring is to start with an 8ft piece at the straightest and longest part of the floor. With the next run or your 2nd row of sub flooring you will start with a 4ft piece of sub flooring and continue this process until finished.