Every structure starts underground.
Post-tension and conventional slabs, spread footings, grade beams and caissons — poured to the soils report, inspected at every hold point, and cured before a single stud goes up. If the foundation is wrong, everything above it is wrong.
CA General Building License #1138219 · Bonded $25,000 · Workers'-comp insured
Post-tension deck, tied out pre-pour · Los Angeles
Five ways to hold up a building
Which one your lot gets isn't a preference — it's what the soils report, the slope and the load path allow. Here's what each system is actually for.
Post-tension slabs
Steel tendons run through the slab in sleeves, then get stressed with a hydraulic jack after the concrete gains strength. The slab ends up in compression, which is what keeps hairline cracking under control on the expansive clay that shows up all over the LA basin. Designed per PTI DC10.5.
Best on: expansive soil, tight infill lots, slab-on-grade homes
Conventional slabs
Mild-steel reinforced slab-on-grade — typically #4 bar on an 18-inch grid over a capillary break and a 15-mil vapor retarder. Simpler and faster than post-tension when the soil is stable enough not to need it, and easier to cut into later for plumbing revisions.
Best on: stable soil, garages, additions, ADUs
Spread footings
Continuous or isolated pads that spread a column or bearing-wall load across enough soil to stay under the allowable bearing pressure in the report. Depth is set by frost-free and competent-soil requirements, not by convenience — we dig to the bearing stratum the engineer called out.
Best on: raised-floor structures, point loads, steel columns
Grade beams
Deep reinforced concrete beams that span between caissons or piers and carry wall loads across soil we don't want to rely on. On a stepped hillside pad, the grade beam is what ties the whole foundation into one rigid element instead of independent pieces that can move separately.
Best on: hillside pads, poor upper soil, caisson tie-together
Caissons & drilled piers
Drilled shafts taken down past the unstable surface material into bedrock or dense bearing soil, cased where the hole won't stand open, then reinforced and filled. This is the answer on the steep lots in the hills where there's no competent soil to spread a footing on at grade.
Best on: steep hillside lots, fill soil, downslope construction
Bare lot to a cured slab
Excavated cut on the left, poured deck on the right. Drag the handle across to see the stage change.
Real FRAMO jobsite photography — no renders, no stock. Confirm final matched pairing per lot before launch.
What you never see again after the pour
A slab is five layers doing five different jobs. Skip one and the failure shows up years later as a cracked floor, a damp finish or a settled corner — long after anyone can see who built it. This is the build-up we pour on a typical LA slab-on-grade.
Governed by CBC Chapter 18 (soils & foundations) and ACI 318 for the concrete itself. Compaction verified before anything goes on top of it.
Eight stages, in the order they actually happen
Scroll the sequence
Soils report review
We read the geotechnical report before we price anything — bearing capacity, expansion index, over-excavation depth. That document sets the whole design.
Layout & staking
Corners, offsets and setbacks staked to the survey. A foundation out of square by an inch here costs a week of framing later.
Excavation & grading
Cut to depth, over-excavate where the report requires, then re-compact and test. On hillside lots this is where the shoring goes in.
Rebar & formwork
Forms set to line and grade, steel tied to the schedule with correct cover and laps, tendons sleeved, embeds and hold-downs placed.
Pre-pour inspection
A hard hold point. LADBS or the deputy inspector signs off the steel, depth and vapor retarder. Nothing gets poured over an unsigned card.
The pour
Placed, vibrated, screeded and floated in one continuous operation, with slump checked and cylinders cast on delivery for testing.
Cure & stress
Kept wet or sealed while it gains strength. On a PT deck the tendons get jacked once the cylinders hit the specified strength — usually a few days in.
Final inspection
Forms stripped, anchor bolts and hold-downs verified against the plan, inspection signed off, and the deck handed to the framing crew.
Which foundation your lot actually needs
Side by side, in the terms that decide it. Bring us your soils report and we'll tell you which column you're in.
| System | Post-tension slab | Conventional slab | Spread footing | Caisson + grade beam |
|---|---|---|---|---|
| Soil it suits | Expansive clay, moderate-to-high expansion index | Stable, low-expansion soil | Competent bearing soil near grade | Fill, unstable or steeply sloping ground |
| Typical LA lot | Flat infill lot, Valley basin | Garage, ADU, single-storey addition | Raised floor, steel column lines | Hillside & downslope lots |
| Build-up | 8–10 in ribbed or uniform deck | 4–5 in slab, thickened edge | Pads or continuous strip below grade | Drilled shafts tied by deep beams |
| Reinforcement | Stressed tendons, PTI DC10.5 | #4 bar at 18 in on centre | Caged mild steel, ACI 318 | Full-depth cages in shaft and beam |
| Relative cost | Moderate | Lowest | Moderate | Highest — drilling and spoil removal |
| Cuts into later? | No — tendons must never be cut | Yes, with care | Not applicable | No |
| Handles seismic drift | Rigid diaphragm, very good | Good with proper edge detail | Depends on tie-together | Best on slopes — anchored below |
The soils report decides. We execute it.
Seismic is not optional here
Most Los Angeles lots fall in Seismic Design Category D. That drives the reinforcement, the hold-down schedule and how the slab ties to the frame above — detailed to CBC Chapter 18 and ASCE 7, not to habit.
Expansive soil moves — plan for it
Clay soils across the Valley swell wet and shrink dry. Depending on the expansion index we either post-tension the slab, over-excavate and replace with engineered fill, or deepen the perimeter — whichever the geotechnical engineer specifies.
Water gets handled at the foundation
Below-grade walls get waterproofed, drained with perforated pipe in gravel, and daylighted or pumped away. On hillside lots this is the difference between a dry garage and an annual problem.
Hillside and infill is our normal
Tight access, neighbours a few feet away, pump trucks on narrow streets, stepped pads on a slope. We work out of Van Nuys and pour within roughly a 60-mile radius, so these are the conditions we build in every week.
What owners ask before we dig
On a straightforward flat lot, excavation through final inspection is usually two to three weeks — the pour itself is one day, and most of the calendar goes to layout, steel, waiting on inspection slots and curing. Hillside work with caissons runs longer because of drilling and spoil removal. We give you a stage-by-stage schedule with the estimate rather than one vague date.
Concrete shrinks as it cures, so fine hairline cracking is normal and not a structural problem. Differential settlement is the real issue, and it comes from soil that was never properly prepared. That is why we over-excavate and re-compact where the report calls for it, test compaction before anything goes on top, and post-tension the slab on expansive clay. Cracks that matter are a soil and reinforcement decision made before the pour, not something you fix afterwards.
Yes — foundation work is permitted structural work, and in the City of Los Angeles it goes through LADBS with an engineered plan and a soils report. We coordinate the permit and the inspection schedule, including the pre-pour hold point where the inspector signs off steel, depth and the vapor retarder before any concrete is placed.
Four things, in roughly this order: how much dirt has to move and leave the site, the foundation system your soils report requires, access for concrete trucks and pumps, and how much shoring the lot needs. A caisson-and-grade-beam foundation on a steep hillside costs multiples of a conventional slab on a flat pad — same house above it. We itemise these so you can see where the money is going.
Regularly — hillside and infill lots are most of what we pour. The answer is usually drilled caissons taken past the fill into competent bearing material, tied together with grade beams, plus shoring during excavation and a proper drainage and waterproofing detail behind any below-grade wall. Send us the geotechnical report and we'll tell you what the lot needs before you spend anything.
Send us your soils report.
Free estimates across Los Angeles. We'll read the report, walk the lot, and come back with the foundation system it calls for and a clear number — same-day response.
framoconstruction.inc@gmail.com · 15321 Saticoy St, Van Nuys, CA 91406