Fontana Concrete Pro pours engineered slabs on ground a soils report has proved, over a 10-mil vapor barrier, steel signed off before a truck is booked. Every estimate is measured and written on site.
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Foundations for Fontana ADUs
Most slabs we pour in this city are the floor of something somebody is going to live in: a detached ADU at the back of the lot, or a bedroom and bath added onto the house. That makes it structural work rather than flatwork. It is designed by an engineer, checked by the city, and inspected with the steel in the ground before any concrete is ordered.
Fontana Concrete Pro was founded in 2019 by Andre Whitfield, who had 18 years of Inland Empire work behind him, and he is on the pad for the steel inspection and again for the pour. Room is the first question in Fontana. Deep lots on the steel-town blocks south of Valley Boulevard usually have space at the back for an 800 square foot unit, while a 1990s tract lot north of the 210 is often near its lot coverage once the side setbacks and a pool are counted.
A habitable slab is engineered work, so it is designed to the California Residential Code, built by a CSLB C-8 licensed crew and covered by liability insurance on every job. Plans, the soils report and every inspection go through the Building and Safety Division on the Build Fontana portal, booked and met by us rather than by you. The finished foundation carries a written workmanship guarantee against defects in how it was built.
Before you build
A slab foundation cannot be poured on top of a patio. That concrete is 4 inches on light base with no footing under its edge, and a plan checker will not pass a habitable floor sitting on it. It comes out first, and the ground beneath is then dug and compacted.
A shallow trough through the garden, often greener than the grass either side of it, marks where a wash once crossed the lot before the streets went in. The material filling it is loose, so that is where the borings go and where a footing has to reach past.
Yards get leveled with whatever was to hand, and a foot of undocumented fill is worth nothing to an engineer. No paper says how it was placed or how it was compacted, so it is either taken out and replaced in tested lifts or the footings are carried through it.
A pad sloping back toward the building has to be regraded before it is built on. A habitable slab stands above the ground around it by design, and a yard running the wrong way puts every February storm at the base of the wall rather than out toward the street.
What's included
Standard on every foundation we build, on one estimate rather than added afterward. Each line is something a plan checker, an inspector or this ground asks for before the concrete is allowed to arrive.
Borings and a bearing value for your lot, or an update to the tract report where the subdivision was graded to one.
A stamped foundation plan sized on that report, so depth, steel and slab thickness are a signed decision rather than a habit.
The plan set goes into Build Fontana under our license, and the plan check comments come back to us instead of to you.
Loose surface material is stripped and the pad rebuilt in compacted lifts, then proof rolled, so the fan gravel below does the bearing.
The edge is turned down into undisturbed ground at the depth the plan calls for, since that is the part carrying the walls.
The rebar mat sits at its designed height instead of on the dirt, with a Ufer ground bonded in for the electrical service.
Under any floor somebody lives on, lapped and taped at every penetration, because moisture through a slab ruins what is laid over it.
We book the setback, under-slab and steel inspections and stand on the pad for each, then hand over the written workmanship guarantee.
Your options
Four foundations we build here, set against what is going on top of them and what the report says is underneath. The engineer picks the row in the end, and the pad your lot gives him is most of that decision.
| Option | Best for | Reinforcement | Ground it suits | Days on site |
|---|---|---|---|---|
| Monolithic slab | A detached ADU of 400 to 800 square feet | Rebar mat with a thickened edge, poured as one | Compacted fan gravel with no fill below it | 6 to 9 days, 7 more before framing |
| Slab on stem walls | A room addition beside an older raised floor | Footing steel with dowels up the stem | Pads that step, or a cut and fill line | 10 to 14 days across two pours |
| Post-tensioned slab | Building over deeper placed fill | Tendons stressed a few days after the pour | Ground the report calls uneven in bearing | 8 to 12 days, stressed before framing |
| Garage or shop slab | A detached garage or workshop, not lived in | Rebar mat, thickened where a wall lands | Any pad compacted and proof rolled | 4 to 6 days, 7 more before walls |
A monolithic pour is one day of concrete and the least digging; stem walls mean two pours and are the only answer on a pad that steps.
Local knowledge
The ground under this city is better news for a foundation than most of Southern California, and the risk it does carry is not the one people arrive expecting.
Fontana sits on the alluvial fan below Lytle Creek, so the soil is sand, gravel and rounded stone. It does not swell and shrink the way the clays do further west, which is what breaks a slab through a season of drought and then rain, and compacted it will take a house without argument. What it hides instead is the occasional soft seam where a wash once ran, and that has a local answer: the borings find it and the footing is taken through it to firm ground.
Which half of the city you are in changes the paperwork more than it changes the pour. North of the 210 the subdivisions were graded to a filed soils report, and an engineer can often update that document for one lot rather than send a drill rig out for fresh borings, which takes the best part of a week off the front of the job. On the older streets south of Valley Boulevard nothing of the kind was ever filed, so the holes are drilled and the pad is designed on whatever they bring up.
Our process
Five stages, and the long one is the plan check rather than the concrete. Most of an ADU foundation is drawings and inspections; the pour itself is a morning. You get honest dates for both halves at the visit.
Andre Whitfield measures the footprint, checks the setbacks against the lot line and opens the ground to see what the pad is made of.
Borings are drilled or the tract report updated, and the engineer sizes the footings, the steel and the slab from what it says.
The set goes into Build Fontana under our license, we answer the comments, and you get the permit number the day it issues.
The pad is stripped and rebuilt in compacted lifts, footings dug, forms set, the barrier laid and the steel tied ready for inspection.
Concrete goes in on an approved pad, the slab is kept damp for a week, then you walk it with the owner and take the guarantee.
What moves the estimate
Footprint sets the floor, and the two things that move it after that are what the engineer asks for and how hard the back of your lot is to reach. Both are known before a figure is written. Every estimate is measured and written on site.
A square 600 square foot pad forms faster than the same area in an L, because footings, edges and steel all follow the outline.
Bearing depth, slab thickness and whether the design goes post-tensioned are the engineer's call, and each one adds material.
A pad reached only through a side gate is dug by mini excavator and poured by pump, which adds days a front yard never does.
Drain lines, water and electrical conduit are set and inspected under the slab before the pour, and the fixture count decides how much.
The visit and the written figure cost nothing, and you hear back within 1 business day once the form reaches the yard. (909) 697-3243 or send us a message.
Send the form or call the yard on Sierra Avenue. Andre Whitfield comes out, checks the setbacks and opens the ground, and writes the figure at your property before he leaves. Nothing is owed for that visit.
Reviews
Three foundations, three lots, and what the owners wrote afterward. All three are structural slabs with something built on top of them, rather than a patio or a drive.
“We were adding a two bedroom ADU at the back and had no idea where to start. They handled the soils report, the engineer and the whole plan check, and I had the permit in hand before I paid for any concrete. Steel inspection passed first time.”
“Our lot is off Merrill and the digger had to come through a six foot side gate. They pumped the whole pour over the roofline instead of taking the fence out. Six hundred square feet, and the framer measured it flat within a quarter inch.”
“The engineer found an old wash line running under our garden, so the footings had to go deeper on that side of the pad. Andre showed me the boring log and the revised drawing before he touched it, and the figure moved by what the extra concrete cost.”
FAQ
Permits, soils reports, vapor barriers and how long the city takes, answered for a foundation in this city rather than for concrete in general.
Footprint first, then the engineer's design. A 600 square foot ADU pad on ground that needs no fill taken out is the simple end of it; deeper footings through a soft seam, a post-tensioned design, a pumped pour to the back of the lot and the plumbing set under the slab each add to that. The report and the plan check are their own lines. Every estimate is measured and written on site, with the ground opened first.
Yes, always. An ADU is a habitable structure, so its foundation is part of a building permit taken out through the Build Fontana portal with a stamped plan set behind it. Inspections follow at the setbacks, at the under-slab services and at the steel, all before the pour. We file the set under our license and stand on the pad for each one, so no counter visit is yours.
For anything habitable, yes, because the engineer needs a bearing value before he can size a footing or a slab. North of the 210 the tract was graded to a report that already exists, and updating it for one lot is often accepted, which saves close to a week. On the older blocks the holes are drilled fresh. Either way the document comes before the drawings, never after them.
A residential slab is normally 4 inches through the field with the perimeter turned down to whatever depth the plan calls for, and a rebar mat tied on chairs so the steel sits where it was designed to sit rather than on the dirt. Bar size and spacing come off the stamped drawing for your lot. None of it is chosen on the day by whoever is holding the tie wire.
It stops ground moisture rising through the concrete. Fan gravel drains fast but it is still damp a foot down, and vapor moving up through a slab lifts flooring, blisters paint and grows mold behind a baseboard. A 10-mil sheet goes over the fill, lapped and taped where pipes come through, under any floor somebody is going to live on.
On site it is 6 to 14 days depending on the type. The wait in front of that is paperwork: borings and a stamped plan take a couple of weeks, and plan check takes as long as it takes, which is why we file early and answer comments the day they land. Once the steel passes the pour is a morning, and the slab cures a week before framing starts.
That is a setback and lot coverage question and it is the first thing measured at the visit. The deep lots on the older streets south of Valley Boulevard usually take a detached unit with room around it. A 1990s tract lot north of the 210 is tighter once the side setbacks, a pool and any patio cover are counted, and an attached addition is often the better answer there.
Rebar for most of what gets built here, because compacted fan gravel gives even bearing and a conventional mat handles it. A post-tensioned design earns its place where a pad sits over deeper placed fill, or the borings show bearing changing across the footprint, since the tendons stiffen the slab enough to bridge it. The engineer makes that call from the report.
Service area
Towns within reach of the yard on Sierra Avenue, nearest first, across 4 counties. The same engineer, the same crew and the same inspections wherever the pad happens to be.
Four jobs that go in with a slab or straight after it, measured on the same visit and itemized on one written estimate rather than quoted twice by two trades.
The footings under a stem wall, dug to the bearing depth the plan sets.
A full foundation for a new build, from the excavation up to the pad.
The finished floor inside the shell, poured level and ready to cover.
The step up to a new ADU door, cast to an even rise off the slab.
Call the yard on Sierra Avenue or send the form and you hear back within 1 business day. Tell us roughly how big the unit is and where on the lot it goes, and the visit can be booked inside the week.