Slab foundation building in Redwood City CA - a house that starts on solid ground
Planning a new house, addition or ADU and need a foundation under it? We dig to firm ground, pack the base and pour a slab built to carry it.
- Licensed and fully insured.
- Free quotes on site.
- Replies within 1 business day.
What goes into building a slab foundation in Redwood City?
Slab foundation building in Redwood City, CA, means forming, pouring and finishing the flat concrete slab your house sits on, built over ground we've dug out and packed so it doesn't settle under you. It's the first thing built and the last thing you'd want to redo.
Most people who call about a slab have plans for a new house, an addition or an ADU, or an old slab that's cracked past saving. The price comes down to the slab's size, how much dirt has to come out to reach firm ground, how much steel it needs, whether a post-tensioned slab makes sense and how easily a concrete truck can reach the lot. The schedule turns on the weather, inspections and the wait before the slab can take weight, and I'll write up an estimate with your own numbers once I've seen the lot.
How do you know it's time for a new slab foundation?
Plans ready, lot still dirt
You've got drawings for a new house, addition or ADU and nothing but bare ground to put it on. Everything above sits on the slab, so this is the step where rushing costs you for as long as you own the house.
Wide cracks in the old slab
Cracks that keep growing, or one side sitting higher than the other, usually mean the ground under the slab moved or the base settled. The longer it waits, the more water gets underneath and the wider the gap gets, and I'll tell you whether it needs a new slab or something less.
Water running toward the house
Puddles against the wall after rain or damp along the floor's edge usually mean the ground or the old slab falls toward the house. Every storm soaks the soil under your foundation again, and wet clay is what swells and shrinks.
How we handle slab foundation building
We start under the slab, because that's where slabs fail. Our crew digs down to firm subgrade, the native ground the slab rests on, then brings in base rock and packs it in layers so it won't sink later the way loose dirt raked flat does. Before the forms go up, I check where the water runs and grade the lot so it drains away from the house. Then the steel goes in, either rebar, the steel bars that hold a slab together if it cracks, or post-tensioning cables, and we pour early in the day so midday heat doesn't leave a weak, dusty top. We cut control joints, shallow grooves that tell the concrete where to crack, before it picks its own spots, then keep the slab damp while it cures so it gains strength instead of drying out. If the budget gets tight, I'd rather spend it on the base than the finish, because nobody sees the base on day one and everybody sees it in year ten.
Some lots need more than a single flat slab, and when a house needs stem walls and footings, that's our foundation installation work. Builders and property owners putting up something bigger often need paving around it too, and our concrete parking lot building starts with the same dug-out, packed base.
Conventional rebar slab
A grid of rebar inside a slab on a well-packed base suits most lots where the ground stays put. It's the straightforward choice, and on stable soil there's no reason to pay for more.
Post-tensioned slab
Steel cables run through the slab and get pulled tight once the concrete hardens, squeezing it together so it holds up better when the ground shifts. On ground that moves, we'll talk through whether it makes sense for your house, and if it doesn't, I'll tell you.
Get a free on-site estimate for your slab foundation
Send the form and you'll hear back from me within one business day. I'll come out, look over the lot, ask a lot of questions and write up a free estimate with no obligation.
(650) 587-4028- Based in
- Redwood City, CA 94063
- Hours
- Mon–Fri: 7 AM–11 PM, Sat–Sun: 6 AM–10 PM
What happens after you call about a slab foundation?
Here's how a slab job runs from your first call to the final walk-through, and who you'll be dealing with at each step.
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Call or send the form
You call (650) 587-4028 or send the form, and you hear back from me. We pick a time for me to come see the lot.
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I look the job over
I walk the lot, ask about your plans, the drainage and the ground, and write up an estimate. If your job needs a permit, you'll hear it from me then.
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Our crew builds the slab
Our own crew does the work, and I check it as it goes. In Redwood City, each inspection comes with a 2-hour window from its listed time, so we plan the day around it.
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We walk it with you
When it's done, we walk the finished slab together and go over when it can start taking weight. Then it's yours to build on.
Why Redwood City homeowners call Elite Redwood City Concrete for slab foundations
If you've got plans for a slab, tell me about the project or call (650) 587-4028, and I'll come take a look.
I look at your lot myself
I come out to see the job in person and ask the questions about your plans and your ground. The person pricing your slab has stood on the dirt it goes on.
In business since 2013
I ran crews and pours as another contractor's right hand for years before starting this business in 2013, which makes 13 years under our own name. You get someone who's seen what happens when the base gets skipped.
Licensed in California, fully insured
We're licensed and fully insured. The state licensing board has a concrete contractor class for firms that form, pour, place and finish flat concrete like a slab, so that's the kind of license to look for in whoever you hire.
Known for the ground work
Most of our calls come from homeowners in Redwood City and the cities around it, plus builders who've used us before, and what they know us for is getting the ground and the base right before any concrete shows up. Every job is backed by our satisfaction guarantee.
Slab foundations, permits and soil around Redwood City
Permits for work in Redwood City go through the city's Building Department, which handles them online for contractors who hold a Redwood City business license. Whether your particular job needs one is something I sort out for your lot, and if it does, we handle the paperwork and inspections with your city or the county. State rules add a step on some lots. Inside the state's mapped seismic hazard zones, a city or county has to require a site-specific investigation by a state-licensed engineering geologist or civil engineer before it issues a development permit. Those state rules exempt a single-family frame home of up to two stories that isn't part of a development of four or more units, though a city can set stricter rules than the state does.
Then there's the clay. About 18% of San Mateo County's mapped soil acres rate high for shrink-swell and another 1% very high, meaning ground that swells when it's wet and shrinks when it dries. We meet that kind of ground on jobs from San Carlos to Menlo Park, so I look at how wet a lot gets and where the water goes before I price a slab.
Questions about slab foundations in Redwood City
How much does a concrete slab foundation cost in the Bay Area?
A reinforced concrete slab in the Bay Area usually runs about $9 to $16 per square foot, going by one Bay Area cost guide, and that's the area's going rate, not our price. Reinforced slabs cost more per square foot than plain concrete pads, and the things covered near the top of this page decide where yours lands. I'll write up your own number once I've seen the lot.
How long does a new concrete slab take before it can hold weight?
A slab should be walkable within about 48 hours, but concrete takes a month to fully cure, according to one Bay Area guide, which allows a week before heavier loads go on. We plan the build so trucks, stacks of lumber and other heavy loads stay off the new slab until it's ready for them.
Is a post-tensioned slab a good choice on expansive soil in Redwood City?
Often, yes. The Post-Tensioning Institute, a national trade group, calls post-tensioned slabs a cost-efficient answer for homes on ground that swells and shrinks, because the tightly squeezed concrete resists soil movement better than a slab without it, and it says they can often go in faster, with fewer pieces and less concrete than a comparable rebar or wire mesh slab. Whether it fits your house depends on the lot and the plans, which is what we talk through at the estimate.
How do I know if a contractor's deposit is too high in California?
For home improvement projects, including accessory dwelling units, the state licensing board caps the down payment at $1,000 or 10 percent of the contract price, whichever is less. Every other payment has to be listed in the contract and tied to work done or materials delivered, so you're paying as the job moves along.
What causes a new concrete slab foundation to crack?
Concrete shrinks as it dries and the ground under it moves, so some cracking is normal, and the American Concrete Institute's national slab guide says completely crack-free floors aren't realistic even with the best design and proper construction. What a good build aims for is cracks in planned places that stay small, which is the job of the base, steel and joints described above.
Who places the rebar in a slab foundation?
On our jobs, our own crew sets the steel, and I check it before any concrete covers it. It's worth asking any contractor, because the state's concrete contractor class leaves out firms whose only business is placing reinforcing steel, and nobody gets a second look once it's buried.
Other concrete work around a new foundation
When the house needs stem walls and footings instead of a single flat slab, or the lot slopes too much for one, this is the foundation for it.
Builders and property owners putting up a new building often need paving around it, and a lot that carries cars every day needs the same careful base.
Service areas around Redwood City
Elite Redwood City Concrete is based in Redwood City, California, and works up and down the Peninsula and into the South Bay. The 12 cities below have their own pages, from San Mateo to Mountain View, and we work in the cities around them too.
Get your slab foundation priced on site
Have the property address and the planned slab size and use handy when you call (650) 587-4028 or send the form, and the first conversation covers a lot more ground.
Redwood City, CA