Greenwood Village Stained Concrete

Big houses hide a lot of concrete. Walkout lower levels, three and four car garages, sunroom slabs, covered terraces off the back, workshop bays that never got finished because nobody could decide what to put down. In Greenwood Village that adds up to more square footage of bare gray slab per property than almost anywhere else we work.

Staining is what we'd do with most of it. Not because it's cheap, though it usually beats what people were pricing instead, but because the color goes into the concrete rather than onto it. There's no seam to lift, no plank to swell, nothing to peel off a slab that's sitting on grade taking on a little moisture the way every slab on grade does. Done right, it's the floor and the finish at the same time.

Where color goes in a house on a big lot

Lower levels come first, and they're the easiest sell once somebody sees a sample. A walkout in Greenwood Hills or Cherry Hills Farm typically has a big open slab that was poured flat, cured under a roof, and then buried under pad and carpet for years. Pull that up and the concrete underneath is usually in good shape and hungry for color. Garages are the second call, and they're a different animal, because a garage slab has spent its life under tires and oil and needs a lot more prep before anything reacts with it.

Outside, the covered terraces work well and the open ones need a harder conversation. Sun at this elevation is unforgiving, and a color that looks perfect on a shaded patio in The Preserve will shift on a west-facing slab that takes six hours of afternoon light. That's not a reason to skip it. It's a reason to pick a colorant that can take it, which is most of what the table below is about.

Newer construction around Sundance Hills gives us clean slabs with no history, which sounds ideal and comes with its own catch: a slab that's only a few months old still has curing compound on it, and that has to come off completely before acid touches anything.

What happens to the slab before any color goes down

• Everything comes up, including tack strip, pad staples, and the mastic ring around old tile
• Degrease the whole floor, then degrease the spots that came back darker after it dried
• Strip or grind off curing compound, cure and seal, paint, and any coating nobody can identify
• Mechanical profile with a diamond pass so the acid can get at the concrete instead of a polished skin
• Patch what needs patching, knowing full well that patch material takes color differently
• Water test in three or four spots, because a slab that won't absorb water won't absorb stain either
• Sample panel in a closet or a corner, cured and sealed, so you're approving the real thing

Acid stain is a reaction, not a paint

Here's the part most people never hear. An acid stain is metallic salts carried in a mild acid solution, and when it hits concrete the acid opens the surface and the salts react with free lime left over from the cement. What you end up with is a mineral deposit sitting inside the top layer of the slab. That's why the color is permanent, why it can't peel, and why it mottles: the reaction follows whatever the concrete has to offer, and no two slabs offer the same thing.

It's also why the step after the color matters more than the color. When the reaction stops there's spent acid and unreacted residue sitting on the floor, and if you seal over that you've bonded your sealer to powder. So the floor gets neutralized, usually with a baking soda solution, then rinsed and vacuumed and rinsed again until the water coming up runs clear and the surface reads neutral. Then it dries. Fully. Not overnight in a closed basement in February, but genuinely dry with air moving across it.

Water-based dyes skip the chemistry. They're pigment in a carrier that soaks in, they come in colors acid can't produce, and they go down faster with far more predictable results. They also don't have the same depth and they don't like ultraviolet light. Inside, dye is often the better answer. Outside, we reach for acid nearly every time.

Which colors survive outside at this elevation

People ask us to guarantee the color will match the sample. We guarantee it'll be in the family. Concrete decides the rest, and honestly that variation is the reason anybody wants this instead of tile.

Straight from the crew