• Installing pre-finished hardwood flooring is similar to the process of installing traditional hardwood flooring. The main difference is that, once it's installed, you're done, with no need to sand, stain and varnish. Most pre-finished systems will have small grooves along the seams, to hide the fact that the floorboards won't be completely even (since they won't be sanded smooth after installation). You'll have to be more cautious with the boards while installing them, taking care not to scratch them up, since you won't be taking off that top layer as with unfinished wood flooring.
  
  

Preparing

• If there's floor trim around the edges of the floor, you'll need to pry it off. Floor trim is a necessity at the end of the project, so if you want to avoid having to buy and cut new trim, keep the old trim intact as you remove it, so you can re-use it. Plywood is the best underlayment for wood flooring, though a previous wood-floor installation will work as well. Either way, staple down a layer of paper or felt underlayment, overlapping the edges slightly. Let your flooring sit in the room for at least a week before you install it, so it can adjust to the environment, which will minimize its movement after installation.
  
  

Getting Started

• All wood flooring, including pre-finished wood flooring, needs to be laid with a gap running around the perimeter of the floor, next to the wall, to allow for floor expansion. Use a chalkbox to snap a starting line 1/2 inch out from the wall where you want to begin, and start flooring at that line. The grooved side of the tongue-and-groove sides of the boards should face the wall, on the line. The first course of flooring needs to be nailed through the top to provide a solid base for the subsequent courses to press against. Use your floor nailer to sink nails in pairs, every foot or so. Connect the boards end to end along the line, cutting the end board on a miter saw as needed.
  
  

Laying the Courses

• Install the boards for the subsequent courses by setting them alongside the previous course, setting a scrap of floor boards against the outer edge, then using a hammer to tap the board into place, hitting scrap to protect the side of the board. Nail the subsequent courses through the sides, using the floor nailer to shoot the nails at a downward angle just above the tongue, which will hide the nail head when the next course is laid. Make sure there ends of the boards don't line up between courses (the flooring will come in varied lengths to give you choices). Work your way across the floor, then length-cut the final course on a table saw to fit against the wall with a 1/2-inch gap. Install (or re-install) floor trim to cover the gaps.