Ontario Concrete Pro pours driveways, barn pads and walls on the acre lots of El Sobrante, down the 15 from Ontario and out Cajalco Road. Every estimate is measured and written on site.
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El Sobrante is built on the granite hills that rise toward Lake Mathews. The ground is decomposed granite over solid rock, with boulders at the surface on most lots, and that is what a slab rests on.
Decomposed granite is a good subgrade when it is undisturbed. It drains, it does not swell, and it compacts hard. The trouble comes where a pad was cut and filled to make a level lot on a slope, which describes most of the houses here, because the fill side of the pad is loose granite sand that was never compacted to the standard of the cut side. A slab poured across the two settles on the fill side and cracks along the line between them, usually in the first 2 or 3 winters.
So the first thing we do on a lot in El Sobrante is find that line. The subgrade is probed along the whole slab, the fill side is dug out and recompacted in lifts, and 4 inches of base goes over both. Number 3 steel on an 18 inch grid ties the slab together across the change, and a boulder that sits in the way is broken out rather than poured around, because rock left under one corner of a slab is a hinge.
El Sobrante is horse property and half-acre lots above Lake Mathews, in the county rather than in any city, so the work here is long drives, pads for barns and shops, and walls that hold a cut in decomposed granite. Little of it is a small job.
A driveway in El Sobrante is long, often 100 feet from El Sobrante Road to the house, and most of it is the gravel the builder left. We grade it, compact 4 inches of base on the decomposed granite, and pour 5 inches with steel where a truck and a trailer turn on it.
Patios here look out over the hills toward Lake Mathews, which puts them on the fill side of the pad more often than not. We dig out the loose granite sand, recompact it in lifts, and pour on 4 inches of base with steel on an 18 inch grid, so the outer corner does not drop away.
Stamped work in El Sobrante is asked for around pools and at the entry, and the pattern owners choose is a flagstone in the color of the granite on the lot, because a slab that matches the boulders in the yard belongs there. We cast it 4 inches thick and seal it in 2 coats.
There is no city sidewalk in most of El Sobrante, so a walk here is the path from the drive to the door and the run from the back door to the barn. We pour it 4 inches thick on compacted base, wide enough for a wheelbarrow, and pitch it away from the house on the granite.
Garage and shop floors in El Sobrante carry a tractor, a trailer and a lift, which is more than a house garage slab was ever poured for. We take a cracked one out to the footings, compact base, lay a vapor barrier and pour 5 inches with steel, flat enough to coat after 28 days.
Decorative work here is an exposed aggregate finish more often than a stamp, since the stone in the mix sits well against the boulders and the dry planting the lots keep. We seed the surface, wash it at the hour the mix allows, and seal it against the dust of a granite lot.
Retaining walls are the job the ground in El Sobrante asks for, because nearly every pad was cut into a slope and the cut wants to come down in the first wet winter. We foot the wall 18 inches into undisturbed granite, drain behind the stem, and engineer anything over 4 feet.
Interior slabs in El Sobrante are for the barn, the shop and the unit the state's ADU rules allow on a lot this size. We pour over a 10 mil barrier on compacted base, 4 inches for a room and 5 for a shop, trowel it flat, and lay the joints out to the room rather than to the crew.
Our yard is on Holt Boulevard in Ontario, and a crew reaches El Sobrante down Interstate 15 to the Cajalco Road exit and east past the lake. That is the better part of an hour, so we book the town in full days rather than half. Because El Sobrante is unincorporated, there is no city hall. Plans and permits go to the Riverside County Building and Safety Department, and a wall or a cut into a slope is reviewed as grading before a permit is issued.
The houses are newer than the land looks. Most of El Sobrante was built from the 1980s on, on lots of a half acre and up along El Sobrante Road and the streets running off La Sierra Avenue toward the lake, with the gated tract at Victoria Grove the one part laid out on city-sized lots. So the work is rarely a tear-out. It is the drive the builder left as gravel, the pad for a barn or a shop, and the wall where a pad was cut into the hill.
The lake sets the weather. Lake Mathews is the end of the Colorado River Aqueduct, and the open water and the reserve around it mean the afternoon wind reaches a pour here with nothing to slow it, which dries a slab faster than the same slab dries in Ontario. From June to September we pour at first light and keep the surface wet under cover for 7 days. In winter the granite drains within hours, so a dry week is a working week here even after a storm.
One crew, one measured figure, and a day planned around the drive from Ontario. On an acre lot the pour is usually the shortest part, since the cut and the compaction of a graded pad take the first days.
Victor Salgado measures the slab, probes the pad for the line between cut and fill, finds the septic and writes the figure before he leaves.
Fill is dug out and recompacted in lifts, boulders in the line are broken out, and 4 inches of base is laid over the whole slab.
A wall, a footing or a barn slab is filed with the Riverside County Building and Safety Department and inspected before the pour.
One morning to pour, joints cut the same day, kept wet under cover for 7 days in summer. Walk on it after 24 hours, drive after 7.
Call or send the form and we will call you back within 1 business day to set a morning for the visit. Victor Salgado walks the lot, probes the pad and writes the figure before he leaves, and the estimate costs nothing, walk or barn pad.
Reviews
Reviews left by homeowners across the towns we cover, El Sobrante among them. The drives, pads and walls behind them are the ones described above, built by the same crew from the same yard.
“Our place off Euclid is from the 1920s and the drive still ran back to the alley. They replaced 400 square feet at 5 inches, matched the fall to the alley apron and cut the joints the same day. Victor was there from start to finish.”
“We built an ADU in the back garden and needed the slab done properly. They over-excavated the old dairy ground, brought in engineered fill and poured to the soil report. It passed inspection first time, which is not what I expected.”
“The warehouse yard on Jurupa Street was breaking up under the forklifts and we could not shut down to fix it. Ontario Concrete Pro poured 2,800 square feet at 6 inches over two weekends so we never stopped shipping. A year on the joints are still tight.”
What people in El Sobrante ask before they book, covering the permit counter for an unincorporated lot, the cut and fill under a pad, septic lines, the long drive and how a job here is scheduled.
Scale, then the pad. A drive on a half-acre lot in El Sobrante runs 100 feet or more, and length sets the concrete and the crew hours before anything else does. Whether the pad was cut or filled sets the preparation, since fill is dug out and recompacted and cut is not. Every estimate is measured and written on site, so the figure comes off the tape and the probe, not off a chart.
Riverside County. El Sobrante is unincorporated, so there is no city counter. Flatwork at grade in your own yard needs no permit. A retaining wall over 4 feet, a footing that carries a roof, a barn slab and any cut into a slope go to the Riverside County Building and Safety Department, and we file the plans and meet the inspector on the lot.
Decomposed granite over rock, with boulders at the surface. Undisturbed it is one of the better subgrades in the county, since it drains and does not swell. The risk is a pad that was cut on one side and filled on the other to make it level, because the fill side settles under a slab. We probe for that line before we form anything and recompact the fill side in lifts.
Not over the tank or the leach field. Many lots in El Sobrante are on septic, and a slab over the field stops the ground breathing and puts a load on lines that were not built to carry one. We locate the tank and the field from the county's record or by probing, and lay the slab out around them, with the tank lid left at grade for the pumper.
Three to four days on site for a long drive or a barn slab, most of it preparation. The pour itself is one morning. Concrete takes foot traffic after 24 hours and a car after 7 days, and a horse trailer waits the same week. Joints are cut within 12 hours, and in the summer wind off the lake the slab is kept wet under cover for the first 7 days.
About an hour, down the 15 to Cajalco Road and east past Lake Mathews. We book El Sobrante in full days, so a crew arrives early and stays until the day's stage is done rather than driving back and forth. The same run covers Norco and Eastvale on the way down, which is how a small job here is fitted in beside a larger one.
El Sobrante lies between Riverside, Corona and the lake, and of the towns around it we cover Norco and Eastvale, both on the run down from Ontario. If your street is on a city line, the page for that town says which counter its permit goes to.
Open the Ontario Office in Google Maps Send the form and we will call you back within 1 business day. The estimate is free, and the work carries a written workmanship guarantee against defects in how it was built.