How to Self Level a Floor 

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How to Level a Floor Before Putting Down Hardwood Flooring
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Transcript:
Just recently, I converted my porch to this Four Seasons room, I insulated the walls, put in state of the art windows so that I could use this room year round. Now it's time to deal with the floors. I want to put in something that will blend with the rest of the house and insulate the room from the cold that's coming through the existing floor.
Not too long ago, I installed a pre-finished oak floor in my kitchen. I love the way it turned out and I want to use the same product out here. Here's my game plan. First, I want to level the existing concrete, then lay down a subfloor and finally install the pre-finished oak on top. The existing floor is made of precast concrete pavers laid on a concrete slab.
Now the existing surface is very uneven and before I can lay anything on top, I'll need to flatten it out. I decided to try a self leveling underlayment, a sort of concrete slurry that I'll pour on top. To make sure the underlayment will bond properly I'm going to use a latex primer or bonding agent. I apply it first around the edges with a wide paintbrush, then mop it on the rest of the floor. I've asked Matt Grandinetti, product specialist with Custom Building Products, to drop by and give me a few tips on how to get the best results. He suggested I set up a production line for mixing. So I pressed a few friends into service. Water is poured into a five gallon bucket, then the dry underlayment is added and mixed using an electric drill. If you need to add a precise amount of water to mix a dry material, you can create a self measuring bucket by simply boring a couple of holes in the side. When the water reaches the prescribed level, the excess simply runs out, guaranteeing a consistent quantity each time since this material sets up in about 20 minutes it's important to mix and pour in a more or less continuous operation. Scott keeps blending the ingredients while Charles carries the buckets into the room.
Yeah, you just want to pour it down. Poured out, it'll flow by itself. What's nice about this product is its very non- labor intensive. It does all the work for you.
I start at the lowest point. The material is sort of like a thick milkshake and it naturally seeks its own level. Each bucketful flows into and blends with the one before, creating in effect, one continuous pouring that can be as flat as the surface of a pond. Now, I suppose it's obvious, but there's one bit of advanced planning that's crucial, I need to finish up near a doorway, a few strokes from a garden rake gets rid of any lumps or voids.
Well, this turned out great. And as you could see, it was really simple to do. I've got a flat and level floor now with just a couple of little problems. Got a hole right here, I think that's caused by the material flowing into a hole or break in the grout underneath and then a little ridgeline running down here. I think this began to set up by the time we poured this. So I'm going to fix those right now.
This is another type of underlayment used to smooth and prepare floors for a variety of floor coverings. Instead of water I mix it up using an acrylic additive, again with a drill. The material is troweled on and can be fitted out to a very thin edge without the risk of chipping or cracking.
Well, the floor is flat and level now, I could put a floating floor system out here right on top of what I've got, but I want as much insulation value as possible and the product that I'm going to finish with is a nail down wood strip. So I'm going to install a subfloor and I'm going to use this material right here. It's called dry core. It's chipboard with a moisture barrier on the back, comes in two by two foot squares. It's got an interlocking tongue and groove edge and as you'll see, it goes down very easily.
I start by placing a spacer strip along the wall and setting the first panel in place. A few taps with a hammer and a block of wood interlocks, the tongue and groove edges. At the end of the first row, I measure to the wall, deduct three eighths of an inch for an expansion gap, then cut the panel on the table saw. This tool, called a pole bar, drops into the gap between the flooring and the wall. By hammering on the striking surface I can drive the joint together. When putting down individual panels or planks like this it's important to stagger the joints so I begin the second row with a half panel. With no nails, glue or master to slow me down, I'm almost finished in practically no time at all. Once the sub-flooring is down, I remove the spacer strips, leaving an expansion gap all the way around the room.