Turning a two-car garage into a workshop: epoxy floor and LED bench lighting

Dana's two-car garage has held two cars, a lawnmower and a pile of boxes for eight years. The plan is to move the cars to the drive and turn it into a woodworking and repair shop: a coated floor that sweeps clean and shrugs off oil and glue, and proper light along the 12-foot bench wall, where the single bare bulb in the ceiling throws Dana's own shadow over every cut. Two calculators cover the numbers: the epoxy flooring cost calculator for the floor and the LED strip power calculator for the bench lighting. The order the work happens in is not the order you might expect, so that comes first.

Sequence: walls and ceiling before the floor

The floor is the most expensive and slowest single job, so it gets planned first. It does not get done first. Anything that involves a ladder, a drill over your head or a drip of paint should happen before the coating goes down, because ladder feet scratch a fresh coating and a dropped screw leaves a dent. Dana's order of work is:

1. Empty the garage and test the slab (below).
2. Any new receptacles or circuits, by an electrician if they are hardwired.
3. Mount the LED channels, drivers and wiring along the bench wall.
4. Grind, clean and coat the floor, then keep off it until it has cured.
5. Move the benches, tool chest and machines back in.

Before buying any epoxy: two quick slab tests

Coatings fail on garage floors for two reasons far more often than for any product fault: a slab that was sealed years ago, and moisture coming up through the concrete. Both are cheap to check. Sprinkle water on a few spots; if it beads rather than darkening the concrete, there is a sealer or a hard trowel finish that has to be ground off. Then tape an 18 × 18 inch sheet of clear plastic tightly to the slab and leave it for at least 16 hours (the plastic sheet method, ASTM D4263). Condensation under the plastic or darkened concrete means moisture is coming through, and that needs a moisture-tolerant primer or a different plan before any kit is opened. Concrete poured recently should have cured for at least 28 days; most kit instructions say so.

Dana's slab passes both tests, but water soaks in unevenly near the door where years of road salt have come in. That settles the primer question in favor of using one.

The floor in numbers

The garage measures 22 × 22 ft, so 484 sq ft. Dana compares kits by what each one covers per coat at the film thickness its maker designed it for, and settles on an example kit at $135 that covers 250 sq ft per coat. These are the inputs:

Input	Value	Note
Floor area	484 sq ft	22 × 22 ft
Number of coats	2	Base coat, then a top coat
Epoxy kit cost	$135	Example price
Kit coverage	250 sq ft	Per coat, from the kit label
Primer	On, 200 sq ft/gal at $40/gal	Example price
Decorative flake	$0.10/sq ft	Light broadcast, example price

The calculator multiplies area by coats, 968 sq ft, and divides by kit coverage: 4 kits for $540.00. Primer is 484 ÷ 200 rounded up, 3 gallons for $120.00. Flake adds $48.40, and the total is $708.40, or $1.46 per sq ft.

One thing to know about the tool: the kit count depends only on the kit coverage figure, taken as the area one kit covers in one coat. If your kit is labelled by coverage per gallon rather than per kit, multiply that by the number of gallons in the kit and enter the product as kit coverage. That is the number that drives the order.

How tight is four kits?

Four kits at 250 sq ft give 1,000 sq ft of coverage against 968 needed, which leaves 32 sq ft, about 3%, for everything that goes wrong: a rougher patch near the door that drinks more material, a batch that starts to gel before it is all spread, a thicker second coat. The primer coat absorbs most of the porosity problem, which is one reason to use it, but 3% is still a thin margin. The tool has no allowance for porosity or roller loss; it assumes the label coverage is what you get.

Dana's answer is to buy a fifth kit from a store that takes unopened kits back, and return it if it is not needed. That costs nothing if the floor goes to plan and avoids a stop halfway through the top coat with a mixed batch already curing. The general case of rounding up to whole kits is covered in the post on epoxy kit counts; this is the practical version of it.

Two more limits of the model. Flake is priced per square foot of the whole floor, so a partial broadcast needs a lower per-foot figure rather than a smaller area. And if your system uses a separate clear top coat that is a different product at a different price, run the calculator twice, once per product with one coat each, and add the results.

Cure time is part of the schedule

A coated floor is not usable as soon as it is dry to the touch. Retail listings for a common DIY kit give about 24 hours before foot traffic and 3 days before vehicles, while the same maker's technical data sheet puts full hardness at about 7 days at 20°C. Most kits also give an application range of roughly 50 to 90°F for both air and slab, and a cold slab slows everything down. Dana plans on a full week before the rolling tool chest and the table saw on its mobile base come back in, because heavy point loads and steel casters are harder on a young coating than tires are. Check the instructions for your own kit, since these figures vary between products.

Lighting the bench wall

The bench wall gets three runs of LED strip, each 12 ft long: one under the wall cabinets lighting the bench top, one along the top of the pegboard and one under the shelf over the miter saw. The strip Dana picked is a 24V high-output strip rated 4.4 W per foot. In the calculator: 12 ft per run, 4.4 W/ft, 24V, 20% headroom, 3 parallel runs.

It returns a total load of 158.4 W, a required supply rating of 190.1 W, a recommended 200 W supply, a current draw of 6.60 A at 24V, and no voltage-drop warning, because each run is well under the tool's 10 m (32.8 ft) single-feed limit for 24V.

Layout	Load	Required (20% headroom)	Tool's PSU	Current	Drop warning
3 × 12 ft at 24V	158.4 W	190.1 W	200 W	6.60 A	No
3 × 13 ft at 24V	171.6 W	205.9 W	240 W	7.15 A	No
2 × 18 ft at 12V	158.4 W	190.1 W	200 W	13.20 A	Yes
1 × 12 ft at 24V (one run per driver)	52.8 W	63.4 W	75 W	2.20 A	No

The second row is what happens if Dana extends each run by a foot to reach the corner: the padded requirement crosses 200 W and the tool steps up to the next standard rating, 240 W. Its size list is Mean Well's LED driver and supply ratings, and other brands step a little differently, so treat the recommendation as a minimum rating and check what the range you are buying from actually offers. The third row shows why the strip is 24V. The same light from 12V strip draws twice the current, and two 18 ft runs each pass the 5 m (16.4 ft) point where the tool recommends feeding from both ends.

The tool's drop warning is a length rule of thumb and nothing more. It does not look at watts per foot, and voltage drop depends on current, so a high-output strip like this one sags sooner than a 1 or 2 W/ft accent strip of the same length. Many installers treat about 5 m (16.4 ft) as the practical single-feed limit for 12V strip and roughly 8 to 10 m for 24V, depending on the strip's copper, so the 12 ft runs here have room to spare. Each run gets its own pair of feed wires back to the driver rather than being chained end to end; the multi-run wiring post explains why, and how to fuse each leg.

One driver or three

A single 200 W driver is the simplest wiring. It is also above 100 W, which is the limit for a Class 2 power source, and Class 2 output is what lets low-voltage strip wiring be treated more simply under the electrical code. Three Class 2 drivers, one per run (the last row of the table: 75 W is the smallest standard size that covers the padded 63.4 W), keep every run inside that limit and mean a failed driver only darkens one third of the bench. Dana goes with three plug-in drivers on a GFCI-protected receptacle, which garage receptacles need under the National Electrical Code anyway. Anything hardwired is a job for an electrician.

Strip is sold in 5 m (16.4 ft) reels, so three 12 ft runs take three reels, cut only at the marked cut points, with about 4 ft of offcut from each. Aluminum channel with a diffuser keeps the strip cooler and stops the individual LEDs glaring off a polished floor, which a new epoxy coat very much is.

The full example budget

Item	Quantity	Example price	Cost
Epoxy kits	4 (tool)	$135	$540.00
Primer	3 gal (tool)	$40/gal	$120.00
Decorative flake	484 sq ft	$0.10/sq ft	$48.40
Floor grinder rental	1 day	$160	$160.00
Crack filler, degreaser, rollers	allowance		$25.00
24V LED strip, 4.4 W/ft	3 reels of 5 m	$38/reel	$114.00
75 W Class 2 drivers	3	$35 each	$105.00
Aluminum channel with diffuser	6 lengths	$12 each	$72.00
Feed wire, connectors, inline fuses	allowance		$30.00
Total			$1,214.40
Fifth epoxy kit, returned if unopened	1	$135	(refundable)

The prices are examples to show the method, not current quotes; kit prices in particular vary a lot by brand, solids content and region, so use your own figures in both calculators. The floor accounts for about three quarters of the spend and the lighting for the rest.

What the two calculators leave to you

• Epoxy: no porosity or loss allowance, no separate top-coat product, flake priced only per square foot of the whole floor, and kit coverage is read as per coat, so a label that quotes total coverage across two coats has to be halved first.
• LED power: all runs are assumed identical in length, the drop warning is a fixed length threshold that ignores watts per foot and wire runs, and the supply sizes are one maker's standard ratings, so check the range you are actually buying from.

Inside those limits both tools give exact answers in seconds, and those answers are what turn a vague plan into a shopping list. For more on supply headroom on its own, see sizing an LED strip power supply.