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LevelQuik RS Coverage Calculator: How Many Bags of Self-Leveler?
Enter your floor area and the average pour thickness to see how many 50 lb (22.68 kg) bags of LevelQuik RS (Rapid Setting) to buy. Custom's coverage chart gives 23–24 sq ft per bag at 1/4 inch; the calculator uses the lower 23 sq ft figure and scales it to your thickness, which matches every row of the chart. The figures come from Custom Building Products TDS-108, published 1/18/2024.
Custom LevelQuik RS coverage
| Thickness | US | Metric |
|---|---|---|
| 0.125 in (3.2 mm) | 46 sq ft | 4.3 m² |
| 0.25 in (6.4 mm) | 23 sq ft | 2.1 m² |
| 0.5 in (12.7 mm) | 11.5 sq ft | 1.1 m² |
| 1 in (25.4 mm) | 5.8 sq ft | 0.5 m² |
| 1.5 in (38.1 mm) | 3.8 sq ft | 0.4 m² |
Source: Custom Building Products Technical Data Sheet TDS-108: LevelQuik RS (Rapid Setting) Self-Leveling Underlayment, Published 1/18/2024, read 2026-10-16.
How the calculation works
bags = area × (1 + waste ÷ 100) × thickness ÷ (coverage at reference thickness × reference thickness), rounded up
Self-leveler volume scales with thickness: twice as thick needs twice as many bags. Low spots in the floor add to the real average thickness, so measure the deepest point and the average before you pour.
Worked example
A 200 sq ft floor poured 0.25 in thick with 10% extra: 220 sq ft to cover. One bag covers 23 sq ft at 0.25 in, so at 0.25 in it covers 23 × 0.25 ÷ 0.25 = 23 sq ft. 220 ÷ 23 = 9.57 bags, so buy 10 (500 lb).
Custom LevelQuik RS key specs
| Product type | Self-leveling underlayment |
|---|---|
| Bag size | 50 lb (22.68 kg) |
| Mixing water per bag (max) | 5.75 US qt (5.4 L) |
| Thickness range | 0.125–1.5 in |
| Coverage (data sheet) | 23–24 sq ft (2.1–2.2 m²) per 50 lb bag at 1/4" (6.35 mm); 46–48 sq ft at 1/8", 11.5–12 at 1/2", 5.75–6 at 1", 3.8–4 at 1.5" |
| Mixing water | 5.25–5.75 US qt (5–5.4 L) clean, cool water per 50 lb bag |
| Thickness | featheredge to 1.5" (3.8 cm) in a single pour; the coverage chart starts at 1/8" |
| Pot life (in bucket) | more than 15 minutes at 70°F (21°C), 50% RH |
| Healing time (ASTM C1708) | more than 18 minutes |
| Walkable | 2–4 hours |
| Install floor covering | ceramic tile and other non-moisture-sensitive coverings after 4 hours; moisture-sensitive coverings after 16 hours (4 hours at 1/8" nominal in moderate conditions) |
| Compressive strength | more than 4,300 psi at 28 days (ASTM C1708) |
| Flexural strength | more than 850 psi (5.8 MPa) at 28 days (ASTM C348) |
| Robinson floor test (ASTM C627) | Extra Heavy, on concrete and on wood subfloors with joists up to 24" (61 cm) o.c. |
| Installed dry density | 105–112 lb/ft³ |
| Temperature | ambient, substrate and product between 50°F (10°C) and 90°F (32°C) |
| Use | interior dry areas and limited covered exterior areas such as entryways and porches; not a wear surface; not for sloped drainage surfaces |
| Item codes | LQ50 (USA), CLQ50 (Canada), 50 lb (22.68 kg) bag |
What LevelQuik RS is for
LevelQuik RS (Rapid Setting) is a calcium aluminate-based self-leveling underlayment from Custom Building Products, the company behind VersaBond, Prism and RedGard. You mix it with water, pour it, and it spreads into a flat surface that is ready for floor covering within hours. It is an underlayment, not a finished floor: Custom says it is not a permanent wear surface and should not be used on sloped surfaces that need to drain.
The data sheet lists a wide range of floor coverings that can go on top: ceramic, mosaic, quarry and porcelain tile, glass tile, natural stone, terrazzo, carpet, wood and parquet, laminate, LVT and LVP, VCT, sheet vinyl and rubber. Suitable substrates include absorbent and non-absorbent concrete, lightweight concrete, gypsum-based underlayment, existing ceramic tile, cement and epoxy terrazzo, exterior-grade plywood and OSB, cutback adhesive residue, well-adhered resilient flooring and properly prepared steel and aluminum. It is meant for interior dry areas, plus limited covered exterior areas such as entryways and porches.
One detail matters for wood-framed houses: Custom rates LevelQuik RS "Extra Heavy" on the Robinson floor test (ASTM C627) over concrete and over wood subfloors with joists up to 24 inches on center.
How the calculator works out bags
For a self-leveler, the depth of the pour decides almost everything. One 50 lb bag makes a roughly fixed volume of material. Custom's chart gives 23 to 24 sq ft at 1/4 inch, which is about 0.48 cubic feet per bag. Pour twice as thick and the same bag covers half the area. That is why the chart reads 46 to 48 sq ft at 1/8 inch and only 3.8 to 4 sq ft at 1 1/2 inches.
The calculator takes your area, adds the waste allowance you choose, and divides by the coverage at your thickness. It uses the low end of Custom's range, 23 sq ft at 1/4 inch, because coming up short in the middle of a pour is the expensive mistake. Scaling 23 sq ft linearly gives 46 at 1/8 inch, 11.5 at 1/2 inch, 5.75 at 1 inch and 3.83 at 1 1/2 inches, which matches the low end of every row in the data sheet. Bags are always rounded up.
Enter the average thickness, not the deepest spot. If the floor has a few deep dips, measure them, estimate an average, or split the room into zones and run the calculator once per zone. A laser level or a long straightedge and a tape measure are enough to get a usable average.
Thickness range
The data sheet says LevelQuik RS can be applied from featheredge to 1.5 inches (3.8 cm) in a single pour. The coverage chart starts at 1/8 inch, so this calculator accepts 1/8 to 1 1/2 inches without a warning. Below 1/8 inch, the bag count still works out, but treat it as a rough figure because the chart does not cover it.
Over wood subfloors, Custom notes that the leveler may need to be 1/2 inch thick to replace cement backerboard under tile or to give a stiff enough base for the floor covering. If you need more than one layer, pour the second as soon as the first reaches walkable hardness. If the first layer has been drying for more than 12 hours, prime it again before the second pour.
Preparation and priming in brief
Every surface must be structurally sound, clean and free of grease, oil, dust, curing compounds, wax, sealers and efflorescence. Custom asks you to prime all surfaces before pouring, using LevelQuik Advanced Acrylic Primer on porous surfaces, MBP Multi-Surface Bonding Primer, or TechPrime E epoxy primer, depending on the substrate. Gypsum underlayment must be sealed or primed first, with a diluted primer coat followed by a second coat.
Plywood and OSB need to meet industry deflection limits, and the data sheet calls for 2.5 lb/yd² metal lath fastened every 6 to 8 inches over the primed surface. Open gaps should be blocked so the leveler cannot run into the next room. Cutback adhesive must be wet-scraped down to a transparent stain; Custom warns that old adhesives can contain asbestos and should never be sanded or ground. Expansion and cold joints are carried up through the leveler and the floor covering, not poured over.
Mixing and timing
Each 50 lb bag takes 5.25 to 5.75 quarts (5 to 5.4 L) of clean, cool water. Add the powder to the water while mixing with a heavy-duty 1/2 inch drill and an egg-beater paddle at 650 rpm or more, for about 2 minutes. Overmixing, or moving the mixer up and down, traps air and can cause pinholes. LevelQuik RS can also be pumped.
Work has to move quickly. Pot life in the bucket is just over 15 minutes and healing time is just over 18 minutes at 70°F (21°C), so keep a wet edge and have the next batch mixing before the last one runs out. Ambient, substrate and product temperatures must stay between 50°F and 90°F (10°C to 32°C); chill or warm the water to get there. The floor is walkable after 2 to 4 hours. Ceramic tile and stone can go down after 4 hours, and moisture-sensitive coverings after 16 hours.
Custom points out that some fine cracking in cement-based self-levelers is normal, especially near sharp wall corners, and that it can show through clear or semi-transparent coatings. Custom recommends pouring a test area first to check bond and appearance.
FAQ
How much does a bag of LevelQuik RS cover?
Custom's TDS-108 coverage chart gives 23 to 24 sq ft (2.1 to 2.2 m²) per 50 lb bag at 1/4 inch. Coverage scales with thickness: 46 to 48 sq ft at 1/8 inch, 11.5 to 12 sq ft at 1/2 inch, 5.75 to 6 sq ft at 1 inch and 3.8 to 4 sq ft at 1 1/2 inches. Custom says the chart is for estimating and real coverage depends on installation practice and jobsite conditions.
Why does the calculator use 23 sq ft and not 24?
The lower end of a coverage range means more bags, and running out halfway through a self-leveler pour is far worse than having a spare bag. Using 23 sq ft at 1/4 inch also reproduces the low end of every other row in Custom's chart exactly, so the result lines up with the data sheet at any thickness.
How much water goes in a bag of LevelQuik RS?
Mix the whole 50 lb (22.68 kg) bag with 5.25 to 5.75 US quarts (5 to 5.4 L) of clean, cool water. Add the powder to the water while mixing with a heavy-duty 1/2 inch drill and egg-beater paddle at 650 rpm or more, for about 2 minutes until it is lump-free. Custom warns against overmixing, which traps air and can shorten pot life or cause pinholes.
How thin and how thick can LevelQuik RS go?
The data sheet says it can be applied from featheredge up to 1.5 inches (3.8 cm) thick in a single pour. Its coverage chart starts at 1/8 inch, so the calculator shows a note if you enter less than that. If you need a second layer, pour it as soon as the first is walkable; if the first layer has dried for more than 12 hours, prime again first.
When can I tile over LevelQuik RS?
At 70°F (21°C) and 50% relative humidity it is walkable in 2 to 4 hours, and ceramic tile, stone and other non-moisture-sensitive coverings can go down after 4 hours. Moisture-sensitive coverings need 16 hours, or 4 hours for a 1/8 inch pour in moderate temperature and humidity. Cold or humid conditions slow this down.
Custom Building Products and Custom LevelQuik RS are trademarks of their owner. This page is an independent estimate based on the published data sheet; check the bag label before mixing.