Harbor Costa Mesa Concrete pours indoor floors over a barrier on compacted sand and trowels them dense enough to shrug off the marine layer, since a floor here gets wet from both sides.
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How a floor is built here
A floor in Costa Mesa is wetted from two directions, and only one of them is the ground. Below it the sand carries moisture up as vapor, which a barrier under the slab stops. Above it the marine layer rolls in most mornings from May to August as air holding more water than a cold slab can keep off its face, and it condenses on the concrete the way it does on a car. No barrier stops that. What stops it is a floor finished dense and sealed, in a room that is heated like a room.
Harbor Costa Mesa Concrete was founded in 2019 by Julian Mercado, after 15 years on crews across coastal Orange County, and he runs the trowel on every indoor pour. The floors asked for here are the garage becoming a rental unit under the state's accessory dwelling law, the studio going up behind a 1950s ranch house, and the shop or workroom in one of the small industrial units on the Westside, where the floor is also the finish and there is nothing to hide a bad one under.
Floors are built to the California Residential Code under CSLB C-8, with liability insurance on every job. A floor inside a building takes a building permit from the City of Costa Mesa, and a garage becoming a dwelling takes the conversion permit with it, so the barrier and the edge insulation are inspected before the truck is called. We file it and meet the inspector. Every floor carries a written workmanship guarantee against defects in how it was built.
Signs to look for
A garage or shop floor that is dark and slick at breakfast and dry by noon is sweating, not leaking. The marine air has laid its water on a surface colder than itself. Once that floor is a bedroom the damp sits under the carpet instead, and the room smells of it within a winter.
A garage floor was poured a few inches below the house so a car could drop onto it, and it falls toward the door so a wash runs out. Framed into a unit as it is, the room has a step at the threshold and a floor running downhill. The new floor is poured level with the house.
A covering laid on a slab that was never given a barrier lets go from the edges inward as the adhesive takes on water from below. The floor was flat and looked dry the week it was laid. The slab has to be replaced with one built dry, or a second covering fails like the first.
A white bloom drying on a slab is efflorescence, minerals carried up through the concrete by water rising from the sand and left on top as the water leaves. It says the ground under the room is wet and the slab has no barrier. Nothing goes over that floor until a new one is poured.
In every floor
Eight things go into every indoor floor at no separate line, in the order they happen, and each answers one of the two ways a floor here gets wet, from the sand beneath it or from the air that settles on it before the sun burns through.
The old garage or shop slab is sawn into pieces the crew can carry, lifted out and hauled the same day, down to the sand it was poured on.
The subgrade is probed for old planter fill and compacted under a plate, since a floor that will carry a wall load cannot settle at its edge.
4 inches of crushed gravel, compacted, breaks the path water takes upward through sand and gives the barrier a bed that will not puncture it.
A 15-mil sheet lapped and taped at every seam and turned up at the walls, so the sand's moisture stops under the slab rather than in the carpet.
Rigid foam at the slab edge on a garage becoming a dwelling, because a warmer floor is a floor the marine air cannot condense on.
The slab is set to the house floor's height and screeded flat, not to the old garage fall, so the door has no step and the room takes flooring.
The surface is power-troweled dense, then sealed once cured, which is the finish that gives a damp morning nothing to soak into.
We check the floor with you against the estimate, barrier, gravel, thickness and flatness, and the written guarantee is handed over before we go.
How it can be finished
Four finishes a room here can take, set against what the floor is for and how it handles a damp morning. The slab under all four is the same, barrier, gravel and 4 inches of concrete, so the table is about the surface you will live on.
| Option | Suits | Surface | Damp mornings | Ready to use |
|---|---|---|---|---|
| Troweled and sealed | A converted garage taking carpet or plank | Dense, smooth, penetrating sealer | Sealed face sheds condensation | 7 days, flooring at 28 |
| Polished concrete | A Westside shop or studio, no covering | Ground to a sheen, densified | Densifier closes the pores it would enter | About 3 weeks with the grind |
| Acid-stained floor | A backyard unit poured to be the floor | Mottled color under two coats of sealer | Sealer does the work, recoat every few years | 7 days, then stained and sealed |
| Broom finish under tile | A bathroom or kitchen taking tile | Textured for the thinset to grip | The tile and its membrane take the damp | 28 days before tile goes down |
A broom finish costs least and is meant to be covered, a polished floor most and is meant to be seen, with troweled and stained between. The sealer fights the air.
Ground and air
Two things wet a floor on this mesa, and the sand is only the first. The second is the marine layer, which settles its water on any slab colder than the morning air from May through August.
The sand under the city drains, which is why the ground here moves so little, but drained sand is not dry sand. Below the room it holds moisture that rises as vapor through anything porous, and a garage slab from the 1950s is a sponge sitting straight on it, poured before anyone put plastic under a floor. The State Streets, Halecrest, Mesa del Mar and Mesa Verde were all built that way. So the first job of a floor here is the barrier, and the second is the gravel that protects it.
The air is the part an inland crew does not think about. From late spring the marine layer sits on Costa Mesa until late morning, and a slab that spent the night at the ground's temperature is colder than the air that arrives. Water condenses on it as it does on a windshield. A finished floor answers that with a dense troweled face, a sealer, and edge insulation on a converted garage so the slab runs nearer room temperature. The same barrier goes under a garage floor that stays one.
Call to sealer
Five stages with one crew, and the person who checks the old slab and the sand under it is the one on the trowel at the pour. A floor inside a building is permitted first, so the barrier is inspected before the concrete is called.
Julian Mercado takes the house floor height, tests the old slab for damp, probes the sand and notes what the room will be, then writes the figure.
You pick a finish against what goes over the floor, and take a date. The building permit, and a garage's conversion permit, go to the City first.
The old slab is sawn and lifted, the sand compacted, gravel laid and compacted, then the barrier taped and turned up, and the City inspects it.
Concrete placed in one pour, screeded to the house floor height, then power-troweled as it sets until the surface is dense and closed.
The floor is kept damp seven days, the sealer or polish goes on once it has dried through, and the paperwork is handed to you on the walk-through.
What moves the figure
The room's size starts the figure and what the floor has to become finishes it. A garage staying a garage and one becoming a bedroom are different jobs on one slab, so nothing is quoted from a photo. Every estimate is measured and written on site.
A two-car garage becoming a unit is the common job, the old slab out, barrier and insulation in, and the new floor raised to the house.
A floor in a rented unit is poured around the tenant's move, on a day the City can inspect, and each unit is written as its own estimate.
A Westside workroom floor carries a bench, a rack or a lift, so it is poured thicker and ground or polished, and the grind is a line of its own.
A polish, an acid stain or an integral color in place of a sealed gray floor adds days of finishing, and each one is priced as its own item.
The visit and the written figure cost nothing, and the call that books it comes within 1 business day. A landlord with more than one unit gets a figure for each. (949) 541-4812 or send us a message.
Send the form or call, and someone rings back within 1 business day to fix a time. Julian Mercado checks the old slab, probes the sand and writes the figure at your property, with the permit and the finish as their own lines on it.
Floors we poured
Three reviews left on Google, Facebook and the BBB, each about an indoor floor rather than a driveway or a patio, and each naming the room it became or the damp it stopped.
“Our garage in College Park was becoming a rental unit and the old floor was wet every gray morning. They cut it out, laid the barrier and the foam at the edge and poured the new floor level with the kitchen. The tenant has been in through a full winter and the carpet is dry.”
“I rent a small unit on the Westside for a woodshop and wanted a floor I could leave bare. Julian Mercado poured it at 5 inches, ground it and polished it over about three weeks. Sawdust sweeps off it, the bench has not marked it, and it is dry when the fog is in.”
“The studio behind our Mesa del Mar house was going to be my mother's, so the floor had to be warm and dry underfoot. They poured it on plastic over gravel, troweled it smooth and stained it a brown that we sealed rather than covered. Nothing has lifted and the room does not smell damp.”
Asked at the visit
What moves the figure, how long a room is out of use, what the estimate covers, which floors the City permits and what is guaranteed once the sealer is on, answered for a room on the mesa.
What the room is becoming, and then its size. A floor under a bedroom carries a barrier, edge insulation and a permit that a workshop floor does not, and a floor that will be seen takes days of grinding or staining that a floor under carpet skips. Then the area, the thickness the use needs, and the old slab that has to come out first. Each is measured at your property and written as its own line.
About two weeks for a sealed floor, and three or more for a polished one. Two days to cut out the old slab and prepare the sand, gravel and barrier, a day for the City to inspect, a morning to pour and an afternoon to trowel, then seven days of curing before anyone walks on it for long. Flooring goes down at 28 days, when the slab has dried through, and a polish takes its own week of grinding after the cure.
Yes. Sawing the old slab, lifting it out and hauling it, along with the dig-out of any soft fill found under it, are written into the figure, and so are the gravel and the barrier. What sits outside it is named at the visit rather than added later, the building permit fee, the framing and plumbing the unit needs, and a slab found thicker than a garage floor usually is. The number you sign is the one on the bill.
Yes, inside a building it does. A slab under a room takes a building permit from the City of Costa Mesa, and a garage becoming a dwelling takes the conversion permit that the state's accessory dwelling law lets a homeowner apply for. The City inspects the gravel, the barrier and the insulation before the pour, and the floor is signed off with the rest of the unit. We file the paperwork and meet the inspector.
Almost never. Policies here treat a slab sweating in the marine layer, damp rising through sand and a covering lifting from it as maintenance rather than as a sudden loss, so the floor is the owner's to replace. A slab broken up by a burst supply line under it, or by a vehicle coming through the garage wall, is the exception. Photograph the floor before anything is cut, and ask your carrier before you book.
How it was built. The barrier and its seams, the gravel, the thickness poured, the flatness, the finish and the sealer, with those terms printed on the estimate you sign. It is a written workmanship guarantee against defects in how it was built. Condensation in an unheated room, wear, staining and a covering laid before the slab had dried sit outside it. Where the fault is ours, we come back and put it right.
A 3,500 psi ready-mix placed the morning it is batched, 4 inches thick under a room and 5 under a shop, over a 15-mil polyethylene vapor barrier lapped and taped to ASTM E1745 and 4 inches of compacted crushed gravel. Welded mesh sits at mid-depth, and rigid foam runs along the edge of a converted garage. The mix, the barrier and the sealer are named on the estimate you sign.
Only for the measurement at the start and the walk-through at the end. Between them the crew needs water, power for the saw and the trowel, and a way in that does not cross the fresh floor, and the room stays empty for the week it cures. If the floor is in a rented unit, the tenant's things come out before the saw arrives, and we pour on the day the City can inspect so the room is not opened twice.
Towns we pour in
The eight nearest towns on the list, with the straight-line distance from the office on Newport Boulevard beside each. Every floor is measured in the room before a figure is written.
Four jobs that tend to be booked with an indoor floor or straight after it, on the same barrier detail, by the same crew, and itemized on the one written estimate.
The same slab on the same barrier, for a garage that stays a garage and stops sweating.
The floor and the footing in one pour, for a new backyard unit rather than a converted one.
The saw work to take an old slab out in pieces, or to open a trench for the unit's plumbing.
A stained or polished finish on the floor you have just poured, so it needs no covering.
Call or send the form and you hear back within 1 business day. Say what the room is now and what it is becoming, a unit, a studio or a shop, and the visit can be booked for a day inside the same week.