Learning these skills will make or break you in a flooring installation. It is the base structure after all that your new floor will be built upon. There are a lot of different actions that are categorized as floor prep. I’ll explain a few.
Skim coating:
This is the process of applying a thin light coat of floor leveling compound with a flat trowel edge held at almost a 90 degree angle to the floor dragging it across the floor in a side to side S-like pattern. This technique is used to cover old adhesive residue, like the black glue used to glue down old 9″X 9″tiles. Also when laying a sheet vinyl floor you can skim coat over an existing vinyl floor, to fill in the old pattern, so it does not show through, to the new floor. This is helpful especially if the underlying floor is concrete, and you don’t want to rip the vinyl off the floor.
Self-Leveling:
This kind of prep is taking a bag of self leveling compound (SLC), mixing it with water to the ratio stated on the bag, and pouring the mixture on your sub floor. The Self-Leveling technique is used when your floor is beyond the scope of skim coating. Usually when you have a height difference in the floor greater than an inch, or if it is a concrete floor that is severely pitted. I’ve also used this method to level a ceramic floor before installing a new floor over the top. Once you start pouring, it is helpful to have a friend mixing up another bucket of leveler, so you can keep the mixture flowing at an even rate over the whole floor. If you let too much time elapse between pours you can end up with ridges in the cement that you have to smooth out later with floor leveling compound. It’s very important to follow the manufactures directions on the bag to the letter. Not following these directions can result in a mixture that will not perform right, causing more problems than helping.
Sanding and screwing:
Sometimes when installing underlayment on your sub floor, or installing a hardwood floor directly to your sub floor you will come across high spots in your sub floor where two pieces of plywood sheets come together. This is called a “high joist”. You must sand these flat before laying down your new flooring. If you don’t, you will transfer this peak in the floor to your new floor, causing a host of problems. A good belt sander is recommended to do the job. While you’re at it, go around and check for screws and nails that are sticking up beyond the surface of the floor, and countersink them by hammering or screwing them down.
Eliminating squeaks in the floor
This is also part of this type of floor prep. Make sure everything is quiet in the house and walk around the floor to find the “offending squeaks”. I usually have a permanent marker in hand and mark it with an X. When I have found all the squeaks I go around with a screw gun and drive deck screws into the floor joist, that runs closest to the mark for the squeak. Most houses are built with the floor joists running 16″ on center, but it’s a good idea if you go down to your basement and check out the spacing before wasting time driving screws into nothing but the sub floor and air. I have actually found cases where the floor joists were 24″ on center!