Slab foundation building in San Rafael CA - a dry, level base for your home
Planning a new home, addition or garage on bare ground? We build the slab on a packed base with a sealed moisture barrier underneath.
- Licensed and insured.
- Free in-person estimates.
- We respond within 1 business day.
What does it take to build a slab foundation in San Rafael?
Slab foundation building in San Rafael means forming, pouring and finishing a concrete base that sits right on the ground and carries your house, addition or garage. At Premier San Rafael Concrete Company we've done this work since 2017, here and in the cities around it, from Petaluma down to Berkeley.
Most people call us with plans for a new home, an ADU, an addition or a garage, and a bare patch of ground where it's going. The price moves with the slab's size and shape, how much digging and base rock the lot needs, which slab type and how much steel the plans call for, and how easily a concrete truck can reach the spot. The schedule turns on the city's permit review, the weather on pour day and the cure the slab needs before the framing goes up on it. I can't give you your number from a phone call, so I come out, look at the site and send a written estimate that lays out each step.
How we build a slab foundation
We lay out the slab from your plans and dig down to firm subgrade, the soil the slab actually sits on, then bring in base rock and pack it in layers instead of raking loose fill flat, because a slab only stays level if what's under it doesn't settle. Once the base is level and packed, we lay the moisture barrier over it with every seam taped and walk the whole sheet looking for tears before any concrete goes in, since one hole lets ground moisture wick up into the floors you'll put down later. Then come the forms and the rebar, the steel bars that hold the slab together if it cracks, set to the plans. We pour early in the day so the top doesn't dry out in the afternoon heat and turn weak and dusty, finish it flat, and keep it damp while it cures, which is the slow hardening that gives concrete its strength. If the budget gets tight, I'd rather you spend on the base than on anything you'll see, because the base gets buried on day one and you can't fix it afterward.
A slab is one way to put a house on the ground. If your project needs perimeter walls, a crawl space or a raised floor instead, that's our foundation installation work, and I'll tell you at the site visit which one your plans point to. The same packed base and drainage planning go into concrete parking lot building, where the slab carries cars every day instead of a house.
A slab for a new house
This suits a new build or a rebuild where the whole ground floor sits on one slab. Plumbing and electrical lines that run through the slab have to be in place and checked before the pour, so we line that up with your other trades.
A slab for an addition
This suits a new room or wing built beside the existing house. The new floor has to meet the old one at the right height, so I measure the existing floor first and set the forms to match.
A slab for a garage or ADU
This suits a detached garage, workshop or backyard unit, where the slab is often the whole foundation. A garage floor usually falls slightly toward the door to shed water while a living space stays flat, so we settle that before the forms go in.
Call while your plans are still being drawn, not after, because slab type, floor height and where the water goes are cheaper to settle on paper than in the ground.
What happens after you call us about a slab foundation in San Rafael?
Here's how a slab job runs with us, from your first call to a finished slab. I'm the one you'll see at the estimate and on pour day, and our own crew does the work.
Call or send a message
Tell us your address, what you're building and roughly how big the slab is. We get back to you and set a time for me to see the site.
I measure and price it
I come out myself, measure, and ask what the slab has to carry and what goes on top of it. You get a written estimate that lays out each step from digging to finish, so you can compare it line by line with other bids.
Settle permits, layout and drainage
Before the pour we settle permits, the layout and where the water goes. The city says its first plan review can take up to 3 weeks, so we set the pour date around that wait.
Form, pour and finish
I'm on site with our crew from the first form board to the last pass on the surface. When we're done, we strip the forms, clean up and tell you when the slab is ready to walk on and to build on.
Get a written estimate for your slab foundation
Send the form and we'll reply within one business day to set a time. I come out myself for a free on-site estimate, and there's no pressure to book.
(628) 234-2042What changes slab foundation building in San Rafael
The City of San Rafael's General Permit Requiring Plan Review covers residential work like new single family homes, ADUs, additions, garages and accessory buildings, and that list doesn't name slab work on its own. That means the list doesn't settle whether your slab needs a permit by itself, so I check with the city's building division for your address, and when a permit is needed, we handle the application and the inspections. The building code in effect when a complete application goes in stays with your project from start to finish, so a complete set of papers locks in the rules you'll build to.
On jobs around San Rafael we see plenty of sloped lots and narrow streets, which changes how much digging the base needs and whether the truck can reach the forms or we pump the concrete in. I plan access at the estimate, and we work the same kind of tight sites on jobs in San Anselmo and Mill Valley.
Slab foundation questions from San Rafael homeowners
How much does a slab foundation cost in San Rafael?
A concrete foundation in the San Francisco area usually costs about $9 to $15 per square foot, and that's what the market charges, not our price. Where your slab lands depends on the things covered at the top of this page, and I put your own figure in writing after I've seen the site.
What is the best slab type for a house foundation?
The best slab type is the one your plans call for, and a post-tensioned slab is worth asking about if your ground moves. The post-tensioning trade group calls these slabs a cost-efficient answer for homes on soil that shrinks and swells, because built-in compression lets the slab resist the strain when the ground shifts. The group says they're also used on stable ground to cut down cracking and reduce or skip control joints, the lines cut so a slab cracks where you choose, and that they can make a slab easier to build. Ask early which type your plans show.
How do I apply for a plan review permit in San Rafael?
You apply online, because all new San Rafael permit applications go through the city's OpenGov system. Plan on the review wait I mentioned in the steps above, and when your slab needs a permit, we file it for you.
How long before I can walk on a new concrete slab?
A new slab should be walkable within 48 hours, and waiting a week before heavier loads is the safer choice. Concrete takes a month to fully cure, so build that month into your plan before the slab carries the full weight of the house going up on it.
What vapor barrier should go under a slab foundation?
Ask your contractor which below-slab barrier they plan to use, because the concrete industry's slab guide says ordinary polyethylene sheeting falls short of the industry standard and shouldn't be used for moisture protection under a slab. A barrier is only as good as its weakest seam, which is why we lay ours the way I described earlier.
What license does a concrete contractor need in California?
California's contractor license board has a concrete contractor class for people who form, pour, place and finish flat and other concrete, and slab foundation work falls under it. It's fair to ask any contractor you're comparing about their license and insurance, and we're licensed and insured.
Related services for your slab project
If you're building on a slope or over a crawl space, perimeter walls and footings may suit your lot better than one slab, and we build those too.
For a shop, office or apartment building, we pour parking areas on the same packed base, laid out so rainwater runs off instead of pooling where people park.
Plan your slab before the permit goes in
Call (628) 234-2042 or use our contact form with your address, what you're building and the slab's rough size, so the first call gets straight to what your site needs.