Hawthorne Torrance Concrete pours the slab an ADU stands on, with a footing under every wall and a sheet beneath, where the tract left a 3-inch floor. Every estimate is measured and written on site.
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The slab as foundation
A garage floor and a slab foundation are two different things, and the difference is at the edge. A floor is 3 or 4 inches of concrete laid on the dirt to keep a car off the mud. A foundation has a footing turned down 12 to 18 inches under every bearing wall, steel through all of it, and a sheet under it so the room stays dry. The garage slabs poured across the Torrance tracts in the 1950s are the first kind, and a bedroom cannot be permitted on one, so the slab is poured new.
Hawthorne Torrance Concrete was founded in 2017 by Kenji Okamoto, after 19 years on South Bay crews, many of them on foundation work, and he sets out every slab from the plans himself. The crew has poured slabs on the open pad behind a house and inside the standing walls of a garage, where the old floor is cut out and carried through the door and the footing dug under the wall still holding the roof up. Each is set to the engineer's drawing, not to the floor that was there.
Every slab is built under our CSLB C-8 license with the California Contractors State License Board, with liability insurance on every job, to plans the City's Community Development Department approved. The inspector sees the trench, the steel and the sheet before the truck is ordered, and the bolts before the framers come. The thickness and footing depth are on the estimate, and the slab carries a written workmanship guarantee against defects in how it was built.
Before the plans
Look at the slab edge where the driveway meets the garage. A foundation shows a thickened edge dropping below grade, and a floor shows 3 or 4 inches of concrete and then dirt. Nearly every 1950s garage here shows the second, and the City will not permit a bedroom on it.
A garage floor poured at grade seventy years ago now sits an inch or two below the lawn and the drive, because the yard has been built up with every new lawn and load of mulch. Water runs to the lowest point. A dwelling slab has to stand above the ground, so the new one sits higher.
A dark stain that comes back with each storm and dries over a week is water rising through the slab, and it means there is no sheet under it. Under a car that is a nuisance. Under a floor finish in a bedroom it is mold inside a season, which is why the code asks for a vapor retarder.
A crack where one side stands higher than the other means the ground has moved and the slab, with no steel in it, has gone with it. That is the urgent one. A conversion on such a slab inherits the movement and its walls crack the same way, so it comes out and the ground is probed.
In every slab
Eight things are in every slab we pour for an ADU, a conversion or an addition, and none is a separate line. Each answers something the old garage floor lacked, from a footing under the walls to a sheet under the room and bolts to hold the frame down.
The garage floor is sawn into panels, broken and carried out, inside standing walls or on the open pad, and the ground under it exposed.
The pad is probed at the corners and the middle, soft topsoil dug out, and the subgrade compacted before any base goes down.
Footings dug under every bearing line to the depth on the drawings, 12 inches or more below the finished grade outside the wall.
Waste and supply lines trenched, sleeved where they pass the footing and pressure tested, because they cannot be reached later.
Compacted rock, a vapor retarder lapped and taped, then rebar in the footings and in the slab held up on chairs at mid-depth.
Bolts and holdown hardware set in the wet concrete on the layout marked from the plans, which is what ties the walls down in a shake.
Troweled to the flatness the floor finish needs, joints cut where the plan allows them, and the slab kept wet for seven days.
The slab checked with you against the estimate, the inspection card handed over, and the written guarantee with it before the framers arrive.
Four ways to pour it
Four slabs for four situations on a lot here, set against where the old floor sits, how the plumbing gets in and what the walls above have to carry. The steel, the sheet and the inspection are the same in all four, so the table is about the shape of the pour.
| Option | Built for | Footing | Old floor | Framers on it |
|---|---|---|---|---|
| Detached ADU slab | A new unit on the open pad behind the house | Turned-down edge, 12 inches or more | None, poured on cleared ground | 7 days after the pour |
| Conversion slab | A garage kept standing and made a home | Dug under the wall still holding the roof | Cut out in panels and carried out | 7 days, walls already up |
| Addition slab | A room added to the back of the house | Doweled to the house footing | Patio or walk broken out | 7 days after the pour |
| Stepped slab | A pad on the Riviera or Walteria slope | Stepped down the fall, deeper into clay | Whatever the cut exposes | 7 days, 28 for a load |
A slab inside standing walls is the most work of the four, because everything leaves through a door, and one on the open pad the least. The stepped one is for slopes.
Tract lots and garages
The garage floor the tract poured in the 1950s decides this job, and the fence line 4 feet from the new wall decides where the pour goes. Neither is changed by the size of the unit.
The tracts of West, North and Southeast Torrance went up on former farmland in the decade after the war, and their garages got 3 inches of concrete on the dirt as it lay, with no footing, no steel and nothing under it, because a garage was for a car. The state's ADU law now lets that garage become a home, and the City permits it as one, which means a foundation under it. So the old floor is cut out and the slab built from the ground up, inside walls held on posts.
The yard sets the rest. A detached unit behind a tract house goes 4 feet off the rear and side fences, which on the flat plain is the low corner of the lot where winter runoff collects, so the slab is set 6 to 8 inches above the lawn and the ground graded away from it. The sewer lateral runs under the house, so the waste line is trenched across the yard before the slab. On the Riviera the footing is stepped into the clay, and where the cut needs holding, retaining walls go in with it.
From plans to framers
Five stages, the same crew at each, and Kenji Okamoto sets out every one from the approved plans. The building permit is in hand before the saw touches the old floor, and the inspector sees the trench before the concrete is ordered.
Kenji Okamoto walks the pad with the drawings, probes the ground at the corners and the middle, checks the old floor's edge and writes the figure.
The plans go to the City's Community Development Department, and the pour is booked for the week after the permit comes back with the depth marked.
The old floor is sawn and carried out, walls held on posts where they stay, trenches dug to plan depth and the plumbing trenched and tested.
Base compacted, sheet laid, rebar tied and chaired, the inspector signs the card, and the concrete is pumped in one morning, bolts set in the wet.
The slab kept wet seven days, the anchor bolts checked against the layout, and the inspection card and guarantee handed to you on the walk-through.
Behind the figure
The plans start the figure and the old floor finishes it. Two slabs drawn the same size can be a day apart in work once the garage floor is cut, which is why nothing is quoted from a drawing alone. Every estimate is measured and written on site.
A detached unit on cleared ground is the plainest job, and the trench depth and the run of the waste line to the sewer set most of it.
A conversion means cutting the floor out through a door, posting the walls and digging a footing under them, the slowest work on this list.
On clay the footing steps down the fall and goes deeper, the cut is drained, and whatever holds the cut back is poured with the slab.
A slab left as the floor is troweled to a tighter flatness and sealed, and the holdown hardware the engineer specified is priced by the piece.
The visit and the written figure cost nothing, and the call that books a day for it comes within 1 business day. Bring the plans if you have them. (424) 484-9860 or send us a message.
Send the form or call, and someone rings back within 1 business day to fix a time. Kenji Okamoto reads the plans on the pad, probes the ground and writes the figure at your house, and it is yours to keep whether you book or not.
Slabs we poured
Three reviews from Google, Facebook and the BBB, each about a slab foundation rather than a driveway or a patio, and each naming what was poured and how the inspection went.
“We converted the detached garage in North Torrance. They cut the old floor out in squares and carried every piece out the side door, dug a footing under the walls with the roof still on, and the City inspector passed the steel and the sheet in one visit. The framers had it eight days on.”
“A 480 square foot unit behind our house in Old Torrance. Kenji Okamoto laid it out from the engineer's drawings, set the slab 8 inches above the lawn because the back corner floods every February, and the waste line was trenched to the street before the pour. It came through the winter dry.”
“Our lot in Walteria falls about 3 feet across the pad. The footing was stepped down the slope in three drops, poured into the clay with a drain behind the uphill edge, and the slab went in over it in one morning. Two winters on and the door frames are still square.”
Before you book
What moves the figure on a slab, how long the pad is open, what the City inspects, what the engineer decides and what is guaranteed after the framers have built on it, answered for a lot here.
The old floor, before the square footage. Cutting a garage floor out through a door and posting the walls to dig a footing beneath them is more work than clearing an open pad, and the footing depth the engineer draws sets how much trench there is. After that it is the run of the waste line to the sewer, and whether the pad is on the plain or stepped down the Riviera clay. All of it is measured and written down.
About three weeks from the saw to the framers, of which one is the cure. Cutting out the old floor and digging the footings takes two to three days, the plumbing and its test a day, base, sheet and steel another, then the inspection, and the pour is one morning. The slab is kept wet for seven days and takes framing on the eighth. What stretches it is the City's review of the plans, which comes before any of this.
Yes, the trenching and the sleeves do. The waste and supply lines under a slab cannot be reached once it is poured, so their trenches, the sleeves where they pass through the footing and the backfill are in the figure, and the plumber's own work is timed so the lines are tested before the sheet goes down. The lateral to the street is a separate run and is named at the visit if it is needed.
The trench, the steel and the sheet, before any concrete is ordered. The inspector from Community Development checks the footing depth against the plans, the bar size and spacing, the chairs holding the mat up, the vapor retarder and the sleeves, and signs the card. The anchor bolts and holdowns are checked again after the pour. Every slab a person lives on takes this permit, a converted garage included.
No. A conversion is an improvement you have chosen, and the old floor being unfit for it is not a loss, so no policy covers the new slab. One case is different. A garage floor broken by a burst supply line or a vehicle can be a covered repair, and if you are converting anyway the claim can go toward the demolition. Photograph the damage before anything is cut and ask your carrier first.
How the slab was built. The footing depth, the compaction, the thickness, the steel, the sheet and the bolt layout, with those terms printed on the estimate before you sign. It is a written workmanship guarantee against defects in how it was built. Cracks inside a control joint, staining and ground movement beyond what the engineer designed for sit outside it. Where the fault is ours we come back and put it right.
What the engineer draws, and for most units here that is a 2,500 to 3,000 psi mix, number 4 rebar in the footings and number 3 or 4 in the slab on chairs at mid-depth, over a 10 or 15 mil vapor retarder on compacted rock. The mix and the bar sizes are printed on the estimate so what arrives on the truck can be checked against the drawings, and the inspector checks the same sheet.
Only for the measurement at the start and the walk-through at the end. Between them the crew needs power, water, the side gate open and the cars off the drive on pour day, when a pump truck stands in front of the house for a morning. If the garage being converted is where you park, plan to leave the cars on the street for three weeks, because the slab cannot take a car and will never be a garage again.
Towns we pour in
Eight towns, nearest first, each with its distance from the office on Hawthorne Boulevard beside it. The same crew pours slabs in all of them, and the figure is written at the property in every one.
Four jobs that tend to be booked with a slab foundation or straight after it, on the same base, by the same crew, and itemized on the one written estimate.
The footing alone, for a porch, a deck or a wall that does not need a full slab.
The wall that holds the cut where a Riviera pad is dug into the slope.
The path from the drive to the unit's door, poured after the framers leave.
The saw work that takes an old floor out in panels a person can carry.
Call or send the form and you hear back within 1 business day. Say whether the unit is a new build or a garage kept standing, and whether you have the plans yet, and the visit can be booked for a day inside the same week.