Slab foundation building in Orinda CA - built to suit the ground under your house
Planning a new home or addition on Orinda's hills? We check how your ground behaves first, then form and pour a slab matched to it.
- Licensed and fully insured.
- Free quotes on site.
- Expect a reply within 1 business day.
What goes into building a slab foundation in Orinda?
Slab foundation building is forming, pouring and finishing a concrete foundation that the ground itself holds up under your house, and at Cornerstone Orinda Concrete we start every one in Orinda by learning how that ground behaves.
Most folks who call us are planning a new house, an addition or a garage, and they want the foundation explained in plain words before any concrete shows up. The price mostly comes down to the size of the slab, how much digging and fill your lot needs, which slab type suits the soil and whether old concrete has to be broken out and hauled off. The schedule turns on the permit steps, the weather and the cure time the slab needs before heavy loads go on it. Your written estimate spells out what's included, so you can see where the money goes before you decide. If the house you have has settled and you'd rather lift it than rebuild, foundation raising may be the better place to start.
How do you know you need a new slab foundation?
Cracks that keep growing
Hairline cracks in an old slab or garage floor are normal, but cracks that widen or step up on one side usually mean the ground underneath moved or the base was never packed. The longer you wait, the more water gets in and the more the edges break apart.
Water sitting by the walls
If rain pools against the house after a storm, the ground likely falls toward the house instead of away from it. A new slab poured without fixing that ends up sitting in wet ground, and every winter you put it off soaks the soil a little more.
Dirt that cracks, then swells
When the dirt on your lot opens wide cracks in late summer and turns soft and sticky in winter, you're likely looking at soil that changes volume with moisture. Designing a slab without knowing that is the costly mistake, because the soil keeps moving after the concrete is in.
How we handle slab foundation building
Before I settle on a slab design, I want to know how the ground under the house behaves, because soil that swells and shrinks with moisture gets treated differently than stable ground or soft ground that squeezes down under weight. Once the design is set, our crew digs down to the subgrade, the native ground the slab rests on, and packs it firm instead of raking it level, since a raked base settles right along with the dirt. We set forms, make sure the finished grade sheds water away from the house and place the rebar, steel bars that hold the slab together if it cracks. We pour early in the day so midday heat doesn't leave a weak, dusty top, then finish it and cut control joints, shallow grooves that give the concrete a place to crack where we chose instead of wherever it likes. Here's the trade-off I'll name up front. The base is buried on day one, so it's the first place folks want to trim the budget, but I'd rather spend your money under the slab than on top of it because no finish fixes ground that moves. We also plan the schedule so the new slab has time to cure, the slow hardening that gives it strength, before heavy loads go on it.
A slab is often one piece of a bigger job. When a house needs perimeter footings and walls or a raised floor instead, that's foundation installation, and we sometimes do both on one addition. The same dig-out, packed base and drainage planning carry over to wide pours like concrete parking lot building, where the slab takes cars all day long.
Conventional reinforced slab
This suits stable ground and most garages and additions, because rebar and a well-packed base are enough to keep it together. It's the simplest to form and pour, which usually keeps the cost down.
Post-tensioned slab
This suits lots where the soil shrinks and swells, since steel cables are tightened after the pour to squeeze the slab together. The trade group for this kind of construction says these slabs hold up better than regular ones on that ground and calls them cost-efficient, so it's worth asking about.
Slab with thickened edges
This suits additions and garages where the plans put the footing in the floor itself, so the slab and its footing go in as one piece. It can save a separate footing pour when the design allows it.
Get a written estimate for your slab foundation
We reply within one business day, and most of the time it's me calling you back. The estimate is free, done on site and comes with no obligation. I walk the lot with you, ask what the slab has to carry and put in writing what's included, like whether hauling old concrete away is part of it.
(925) 257-6590Slab foundation building in Orinda and what the city asks for
Orinda requires a building permit before anyone builds or alters a building or structure, and those permits are issued by the Contra Costa County Building Department. A project that needs a building permit also needs review and approval from the city's Planning Department unless it's on the city's exempt list, so on a new slab that planning step is one of the first things to sort out. The city's building permit page lays out what applies, and on your job we check with the right office before we start rather than guess. When your job needs a permit, we can pull it as your contractor and handle the paperwork for our part of the work. If an engineer or architect is involved, we build from their plans and stay in touch with them as we go.
We're based in Orinda and pour on both sides of the hills, and lots around here tend to be sloped, with tight access and water running downhill toward whatever we build. So I spend extra time on where the water goes and how we get forms and the truck in, and we see the same kind of hillside lots on jobs in Moraga and Lafayette.
What happens after you call about a slab foundation in Orinda?
Call and I walk the lot
You call or send the form, and I come out to hear what you're building and look at the ground, the water and anything in the way. I'll also ask what the slab has to carry, since a garage floor and a house foundation aren't the same job.
Get your written estimate
You get it in writing with the slab type, the size, the digging and whether hauling is included, so nothing turns up as a surprise later. If the number is more than you planned, we can talk through which choices move it.
Line up permits and marking
Once you're ready, we line up any permits and get underground utilities marked before anyone digs. Nobody wants to find a gas line with a shovel.
Prep, pour and walk through
Our crew preps the base, forms, pours and finishes the slab, and when it's done I walk the finished work with you before we pack up. We'll go over when it's ready for foot traffic and when it's ready for heavier loads.
Frequently asked questions
How much does a concrete slab foundation cost in the Bay Area?
A concrete slab in the Bay Area usually costs about $9 to $18 per square foot, and that's the going market range, not a quote from us. Where your job lands depends on the size, the slab type, how much digging and fill the lot needs and whether old concrete gets hauled away. The written estimate from our visit gives you your own number.
How long does a new concrete slab take to cure before I can use it?
One Bay Area guide says a new slab should be walkable within 48 hours but takes a month to fully cure. The same guide suggests waiting a week before heavier loads go on it, and we build cure time into the schedule before heavy loads are planned.
When does slab site work in Orinda need a grading permit?
Orinda requires a grading permit when a project digs out 50 cubic yards or more, digs more than 5 feet below natural grade, or places 200 cubic yards or more of fill. So it comes down to how much dirt comes out and goes in at your slab site, which is part of what I look at on the walk. When a grading permit applies, a qualified professional has to design, stamp and sign the grading plans.
Can I build a slab foundation near a creek in Orinda?
Sometimes, because the city says building near a creek may be possible within its creek setbacks or the guidance of its Public Works and Engineering Department. Work inside a creek setback will require an Exception Permit, so tell us how far the slab would sit from the creek and we'll check with the city before planning anything.
What causes a new concrete slab foundation to crack?
Small cracks in a new slab usually come from the concrete shrinking as it dries, which is normal, while the bad ones come from ground that settles or moves underneath. A base raked level instead of packed, water running under the slab and joints cut late or skipped are the usual culprits. We plan for a little cracking with rebar and control joints so the cracks that show up stay small and land where we chose.
Do I have to recycle construction debris on an Orinda home addition?
Yes, in Orinda a residential addition that makes the home bigger must send at least 65% of its construction and demolition debris to an approved recycling facility. If old concrete is coming out for your slab, ask how we'll haul it, and your estimate will say whether hauling is part of the job.
Orinda, CA
Plan your slab foundation, starting with the ground
Call (925) 257-6590 or use the form with your lot address, the slab size in square feet and how far the work sits from any creek, and I'll show up ready to talk about your ground.