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Installer & Pro Supplies

Self-Leveling Compound and Underlayment

A new floor is only as flat as what's under it. Self-leveling compound (also called self-leveling underlayment, SLU or floor leveler) is a pourable cement-based mix that flows out to create a flat, smooth surface before you set tile, click down luxury vinyl or install engineered wood. Our team can help installers and serious DIYers across the Flathead Valley match a leveler and primer to the floor.

Request samples & a quote

Samples carry a shipping charge and a deposit, confirmed by our team before anything ships.

What self-leveling compound is (and isn't)

Self-leveler is a high-flow cementitious underlayment. You mix it with water, pour it, and it spreads and settles to a smooth plane with minimal troweling. UZIN, for example, describes NC 150 as a "high flow self-leveling compound" for interior floors, applied from 1/16" to 1" thick.

It is not the same as outdoor "self-leveling concrete" or resurfacer for driveways and patios. If you're searching for self-leveling concrete to flatten an interior slab before new flooring, an interior self-leveling underlayment is usually the product you want. Always confirm on the product data sheet.

When you need a self-leveler

Under luxury vinyl plank

Rigid-core and glue-down vinyl telegraph dips and humps. Most LVP manufacturers publish a subfloor flatness requirement; if your floor misses it, level first. See our luxury vinyl collection.

Under tile, especially large-format

Big tiles bridge low spots poorly, which leads to hollow spots and uneven edges (lippage). Flatten the floor first, then pair it with a tile leveling system. Browse tile and stone.

Under engineered hardwood

UZIN lists engineered wood among the coverings NC 150 can go under. Check your wood manufacturer's flatness and moisture requirements too. See engineered hardwood.

Over old floors

Some levelers go over well-bonded existing tile, terrazzo or adhesive residue. UZIN lists "well-bonded adhesive residues (including cutback adhesive)" as suitable for NC 150.

For small dips or ramps, a patch may be faster than a full pour. Ask about Uzin #888 Extreme Patch, #886 Feather Patch and 182 Deep Patch Ramp.

How to use self-leveling compound: prep and priming basics

Every product has its own data sheet. Treat it as the rulebook. The general sequence:

An uneven subfloor with primer and a poured self-leveling layer creating a flat surface on topFlat surface for flooringSelf-leveler
Illustration: primer on the substrate, then a poured leveler to a flat plane.
  1. Get the substrate sound and clean. Remove loose material and vacuum. On bare concrete and other surfaces you know are suitable, grind or scrape high spots. Do not sand or grind unknown old flooring or adhesive; have suspect material assessed before disturbing it. Leveler bonds to the surface, not to dust.
  2. Control the pour area. Seal gaps, dam off doorways and set perimeter foam so the mix doesn't run under walls.
  3. Prime. Primer controls absorption and improves bond. UZIN's PE 260 is made for "priming substrates prior to the application of cement or gypsum based UZIN patching or self-leveling compounds," and UZIN states it is "ready for self-leveling after 60 – 90 minutes" at 70°F and 65% humidity.
  4. Watch temperature. UZIN lists a minimum application temperature of 50°F at floor level for NC 150. Montana shoulder-season jobs in unheated spaces need a plan.
  5. Mix and pour to the data sheet. Use the specified water ratio, pour in continuous ribbons and use a spiked roller or gauge rake as directed.
  6. Respect cure times before flooring. UZIN rates NC 150 walkable in 2–3 hours, with time-to-cover set by its coverage chart and depth.

Self-leveler over plywood

Wood subfloors can be leveled, but they move more than concrete, so product choice and priming matter. UZIN lists APA Exposure 1 plywood and OSB as suitable substrates for NC 150, and its PE 260 data sheet calls for applying the primer undiluted on plywood and OSB. Check the data sheet for any minimum thickness, reinforcement or subfloor stiffness requirement before you pour. UZIN also makes NC 150F, a fiber-reinforced version.

Self-levelers and primers to ask about

Manufacturer product information. Availability, colors, sizes and quantities are confirmed in your written quote.

Not sure which one fits your floor? Tell us the substrate, the depth you need to fill and the flooring going on top, and we'll help you match a leveler and primer.

Source: manufacturer data. UZIN product data sheets

Outside the Flathead Valley? We ship flooring and tile.

Northern Lights Design supplies flooring and tile to homeowners, builders and designers in markets without a local showroom. Start with samples, get a written quote, and we'll arrange shipping to your project. Terms are confirmed in your written quote.

Our approved shipping covers flooring and tile. Ask our team about setting materials such as grout, levelers and spacers when you request your quote.

How regional project delivery works

Start with samples

Tell us about your tile, substrate and project, and our team will review the products and put them in a written quote. Northern Lights Design supplies materials only; we do not install.

Request samples & a quote

Samples carry a shipping charge and a deposit, confirmed by our team before anything ships.

Self-Leveling Compound FAQ

In most flooring use, they mean the same thing: a pourable, cement-based product that creates a flat surface before the finished floor goes down. Manufacturers use both names.

Yes, with the right product and prep. UZIN lists APA Exposure 1 plywood and OSB as suitable substrates for NC 150 and specifies PE 260 primer applied undiluted on plywood and OSB. Follow the data sheet for any reinforcement or thickness requirements.

Yes, in nearly every case. Primer controls how fast the substrate pulls water from the mix and helps bond. Use the primer your leveler's manufacturer specifies.

It depends on the product. UZIN NC 150 is rated from 1/16" to 1". For deeper fills, check the data sheet or ask us about other options.

Check the data sheet for your product and depth. UZIN rates NC 150 walkable in 2–3 hours, with time-to-cover based on its coverage chart.

Northern Lights Design supplies materials only and does not provide installation. Always follow the manufacturer's current product data sheet.