Flooring Preparation

Good floors start underneath — we make sure yours do.

Good floors start underneath — we make sure yours do.

Proper preparation is the difference between a floor that lasts two years and one that lasts twenty. We handle grinding, leveling, moisture testing, and subfloor repairs before a single plank goes down.

What's Included

  • Floor Grinding: Diamond-grind removal of old glue, paint, thin-set, and residue. We get slabs down to clean, bondable concrete.
  • Subfloor Leveling: Self-leveling compound rated for 1/2-inch depth correction. We check flatness to ASTM standards before pouring.
  • Subfloor Repair & Reinforcement: Screw-down for squeaky plywood, sister joists where needed, and OSB replacement for water-damaged areas.
  • Moisture Barrier Installation: 6 mil poly vapor barriers on every slab install, plus moisture-mitigating primers when RH probe readings exceed manufacturer specs.

Why Inland Empire Slabs Need Extra Prep

Temecula, Murrieta, and Menifee sit on expansive clay soil. When it rains, clay swells. When summer hits 110°F, it shrinks. That seasonal movement transfers directly to your concrete slab — hairline cracks appear in nearly every home south of Rancho California Road. This prep work is essential before any flooring installation can begin. Before installing any flooring, we fill cracks with flexible polyurea filler — not rigid epoxy that will crack again in six months. For slabs with significant deflection, we use self-leveling underlayment rated for half-inch depth correction. We check flatness to a 3/16-inch tolerance over 10 feet, which is the threshold most LVP and hardwood manufacturers require for warranty coverage. This prep work adds a few hours to the job. It also prevents your new floor from telegraphing every crack and dip within the first year.

Moisture Testing: The Step Most Installers Skip

Concrete is porous. Even in dry climates, slabs wick moisture from the ground below — especially in homes without a proper vapor barrier under the foundation. Excess moisture causes adhesive failure, mold growth under floating floors, and warping in engineered hardwood. Homes in Lake Elsinore near the lake basin are especially prone to elevated moisture readings. We run two types of tests on every slab: calcium chloride tests (measuring moisture vapor emission rate in lbs/1000 sq ft/24 hrs) and in-situ relative humidity probe tests at 40% depth. If readings exceed the flooring manufacturer's threshold — typically 3 lbs MVER or 75% RH — we apply a moisture-mitigating primer or epoxy before proceeding. This is not optional. It is the single most important step in flooring prep, and the one most commonly skipped by installers trying to save time.

Plywood Subfloors: What We Check

Second-story and raised-foundation homes across the Inland Empire have plywood subfloors that develop squeaks, soft spots, and delamination over time. Before installing new flooring, we walk every square foot and mark problem areas. If old flooring needs to come out first, our demolition team handles the tearout and gets the subfloor ready for evaluation. Squeaky spots get screwed down to the joists with coarse-thread screws at 6-inch intervals. Soft or water-damaged sections get cut out and replaced with matching-thickness plywood or OSB. We check joist spacing and condition — if a joist is cracked or undersized, we sister a new one alongside it. For floating floor installations, we also check flatness. Plywood subfloors develop humps and valleys over time, especially at panel seams. We sand high spots and fill low areas to bring the surface within tolerance. Once the subfloor is solid and flat, we move into product installation with confidence that the foundation underneath will hold.

Frequently Asked Questions

Do I need subfloor prep if I'm installing over existing flooring?

It depends on the existing surface. We can install LVP over flat, well-bonded tile or vinyl. But if the existing floor has cracks, loose tiles, or moisture issues, we remove it and prep the subfloor properly.

How long does floor grinding take?

A typical room takes 2–4 hours depending on what is being removed. Whole-home grinding for thin-set or carpet glue usually takes a full day.

Is moisture testing really necessary in Southern California?

Yes. Even in dry climates, slabs wick moisture from the soil below. We see failed moisture tests regularly in Temecula, Murrieta, and Lake Elsinore homes — especially those built on clay soil without proper sub-slab vapor barriers.

What is self-leveling compound?

It is a cement-based product that flows into low spots and cures flat. We use it to correct uneven slabs up to 1/2 inch deep, bringing the surface within the flatness tolerance required by flooring manufacturers.

Get your subfloor evaluated free — we check before we quote.

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