What slab lift is and how you start the first year

Last updated 2026-08-21

What is slab lift?

Slab lift raises a sunken concrete slab by pumping material under it until the panel moves back toward the elevation you marked. Crews drill a grid of holes, inject cement grout or two-part polyurethane foam, watch the lift, then patch the holes. That is the method. It is a repair. It is not a new foundation.

People also call it slabjacking, mudjacking, foam lifting, or polyurethane injection. The names fight about the material. The job is the same idea. You fill a void, then use pressure or expansion to put the slab closer to where the original pour sat.

A typical residential candidate is a driveway panel that dropped at a joint, a sidewalk that now trips people, or a garage floor that ponds. Warehouse aisles and some highway slabs get the same treatment at a different scale. You are usually fighting washed-out base, poor compaction, a leaking line, or freeze-thaw. You are not fixing a house that is dropping on its footings. That is a different trade with piers, and mixing the two in a sales pitch is how you inherit a structural complaint.

Code still cares about the slab you leave behind. The 2021 International Residential Code sets a 3.5 inch minimum thickness for concrete floor slabs supported on the ground ^[1]. A lot of exterior flatwork sits in that same range. A 4-inch driveway panel that is cracked but still acting as one piece can often take a lift. A panel that is rubble cannot.

I would not sell a lift on a slab you can kick apart. Replacement is cleaner. You will not get the spring callback when the next freeze finishes what the last one started.

How do you start slab lift?

You start on paper, not with a pump. Confirm whether your state or city treats this as concrete contracting, foundation repair, waterproofing, or general contracting. The label changes the test, the bond, and who will issue a permit. Then form an entity, get an EIN, open a bank account that is not your rent account, buy insurance, write a contract a homeowner can read, and train on the two hazards that actually show up on this work: respirable silica from drilling and isocyanates from foam.

The IRS lets you apply for an Employer Identification Number online at no charge ^[8]. Do that before you print invoices. The U.S. Small Business Administration walks through entity choice (sole prop, LLC, S corp) on its business-structure page ^[9]. I would form an LLC in most states if you are about to put expanding chemicals and a truck on other people's property. Talk to a local CPA on the tax election. Do not take entity advice from a foam salesman.

Do not buy a rig in week one. Rent or subcontract a few jobs if your license and insurance allow it. You need to see how long a driveway actually takes when the homeowner's car is still in the garage and the HOA wants the holes invisible. Buying a proportioner before you have a bid process is a fast way to finance a trailer that sits.

Permits are local. Some building departments shrug at a driveway lift. Some want a permit, photos, and a note that you will match the existing slope. Call them. Ask who licensed this work last month. Write down the name of the person who answered.

Hiring comes later. If you add employees, most states require workers compensation. Texas is the loud exception for private employers, and even there the statute is specific, so read it or have counsel read it before you assume you can go bare ^[13]. I-9s, a written safety talk, and SDS on the truck are not optional once a second person is on the drill.

Is slab lift the same as mudjacking or foam lifting?

Mudjacking (also called slabjacking) is slab lift with a cementitious slurry. Foam lifting is slab lift with expanding polyurethane. Both raise a panel. Both leave patched holes. The differences that matter on a real job are weight, cure time, hole size, and what happens if you overshoot.

Slurry is heavy. That can help when you want mass in a large void. It can also add load to weak soil. Foam is light and expands. It fills irregular voids and sets in minutes, which is why it shows up on driveways that need cars back that afternoon. Foam is also less forgiving if you keep injecting after the slab is already high. You can crack a panel or create a hump you then have to grind.

I treat them as two tools, not two religions. Interior warehouse slabs with tight downtime often point to foam. Large exterior voids with cheap access sometimes still point to grout. If a manufacturer tells you one material never fails, they are selling. Ask for the SDS, the in-place density range, and a written procedure for stopping a lift.

Neither method is piering. If the real problem is a footing going down, injecting under a 4-inch slab will not save the house. Say that out loud before you take the deposit.

Do you need a contractor license for slab lift work?

Often yes, and the only safe answer is the one your state or city board gives you for the address on the job. Many jurisdictions treat paid concrete repair above a dollar threshold as contracting. Florida's construction licensing statute says a person who wants to contract statewide must establish competency and be certified, and a person who wants to contract on other than a statewide basis must be registered unless an exemption applies ^[6]. California makes it a misdemeanor to act as a contractor without a license. Business and Professions Code section 7028 states: "It is a misdemeanor for a person to engage in the business or act in the capacity of a contractor within this state without having a license therefor" ^[7]. New York City runs a separate Home Improvement Contractor license with its own checklist if the work is on a residential building there ^[15].

The classification name will not say "slab lift." Look for concrete, masonry, foundation repair, or a specialty you can actually test into. Some states let a registered general contractor subcontract the injection. Some cities still want the person on site to hold the card.

There is usually a small-job exemption. The dollar figure moves. Do not quote a blog's number on a contract. Confirm the current threshold, the test book, the bond, and the application fee with the board that will print the license. Nobody honest can promise you an approval date.

Working without the right card turns a simple driveway dispute into a citation and a lost claim. If a GC asks for your license number before they ask for your foam brand, that is the grown-up part of the market. Give them a real number.

What insurance do you need before you take a job?

You need a commercial general liability policy that actually describes concrete raising or concrete repair, plus auto coverage on the truck that hauls the chemicals. If you have employees in most states, you need workers compensation. If a general contractor is hiring you, they will also ask for additional insured status, a waiver of subrogation, and sometimes an umbrella. Inland marine (equipment) coverage matters once the proportioner costs more than the truck.

Do not invent a premium in your head from a forum post. Carriers price this by state, claims, and whether you cut, weld, or go inside buildings. Get a quote from someone who has written concrete or foundation repair, not a personal-lines shop that is guessing.

Read the exclusions. Pollution and "your work" exclusions are where foam and grout claims go to die. If you over-lift a slab and crack a tile floor, you want to know before the claim whether the policy treats that as a covered occurrence. Ask in writing.

Certificates are part of the job packet. Keep them with the contract. For a fuller walk-through of what policies show up on this trade and how people budget them, see what slab lift insurance you need and what it costs. Related notes on the same paper trail sit in slab lift guide 11 and slab lift guide 23.

I would not step on a customer's driveway without a current COI in the cab. Pride is cheaper than a slip-and-fall story.

What equipment do you actually need on day one?

On day one you need a way to locate utilities, a drill that opens clean holes in 4-inch concrete, a pump or foam proportioner you know how to shut off, injection ports, a level you trust (laser or a good digital level), PPE, cones or barricades, and a patch material that matches the slab well enough that the homeowner stops staring at the holes. You also need water, extra hose, and a written mix or ratio sheet taped inside the door.

For grout, that means a mixer and a slurry pump. For foam, that means a two-component proportioner, heated hoses if the manufacturer requires them, and a way to keep A and B at the temperatures on the technical data sheet. Cold material that is off ratio is how you inject sticky junk that never expands and still bills like foam.

Skip the giant used rig with mystery hours until you have ten jobs behind you. A clean rental and a helper teach you more than a bargain machine with a cracked heater. Buy traffic control gear before you buy extra guns. A driveway that dumps onto a collector street is a traffic job, not a chemistry job.

Measuring tools are not optional toys. If you cannot show the customer a before-and-after reading, you are arguing about feelings. I mark joints, take photos with a tape in the frame, and write the lift target on the work order. That habit saves more money than a second proportioner.

What safety rules apply when you drill and inject?

Two federal rules show up on almost every slab lift: silica from drilling concrete, and isocyanates if you shoot polyurethane. OSHA's construction silica standard says: "The employer shall ensure that no employee is exposed to an airborne concentration of respirable crystalline silica in excess of 50 μg/m3, calculated as an 8-hour TWA" ^[2]. OSHA also published a construction fact sheet (OSHA 3681) that restates the 50 μg/m3 PEL and the 25 μg/m3 action level ^[14]. Use wet methods or a shrouded vac rated for silica. Do not dry-sweep dust into the customer's flower bed and call it cleanup.

OSHA Table Z-1 lists a ceiling of 0.02 ppm for methylene bisphenyl isocyanate (MDI), the family of chemicals in many slab-lift foams ^[3]. Read the SDS. Wear the gloves and respirator the SDS names, not the ones that were on sale. Hazard communication is its own standard. You must keep the SDS available and train people on the hazards in the workplace ^[12].

Construction PPE is not a suggestion. OSHA requires PPE wherever hazards of process or environment can cause injury, and the employer pays for it ^[11]. Hard hats on active sites, eye protection on the drill, hearing protection on a long day of coring, boots that survive wet slurry. Simple.

Traffic and pedestrians are the other injury source. Sidewalk work is public-facing. If you leave a 1-inch lip overnight, you built a trip. Cone it, plate it, or do not leave it.

Confined crawl spaces under porches are a different animal. If you are in a space that meets OSHA's confined-space rules, stop freelancing and follow that program. Most driveway work is open air. Do not pretend every job is open air.

How do you price a slab lift job without guessing?

You price from yield, access, and risk, not from a national average you saw in an ad. Measure the area, estimate void depth, decide grout versus foam, then convert that to material units you actually buy. Add drill time, patch time, travel, disposal, and a contingency for a hidden void that eats a second set of sets. Then add overhead and a profit number you can defend when the job runs long.

Per-square-foot bids only work after you know your material yield on your soil. A 200-square-foot panel with a 1-inch void is not the same job as a 200-square-foot panel sitting on a washed-out trench along a downspout. Bid those the same and one of them teaches you a lesson.

I would refuse lump-sum work on a slab you have not sounded or scanned in some way. A hammer and a careful walk still find hollow spots. Write allowances for extra material in the contract so a surprise void is a change order, not a fight in the driveway.

Do not copy another city's price list. Labor, dump fees, and foam freight move. Keep a simple job-cost sheet for the first 20 lifts. If a worksheet helps, SlabLiftPath sells a $149 one-time Mix + Bid-per-Sqft Kit at /start. A notebook and honest quantities also do the job.

Change orders are part of pricing. Photos and a signed extra before you shoot more foam. That is the whole trick.

What chemicals and paper follow polyurethane foam?

Two-component slab-lift foam is a reaction in place. Part A is typically an isocyanate. Part B is a polyol blend with catalysts and a blowing agent. Off-ratio material can stay tacky, shrink, or generate heat you did not plan for. Follow the manufacturer's temperature window. A cold drum in January is not "close enough."

Keep the SDS for every lot on the truck and in a shop binder ^[12]. Train anyone who opens a drum. Store chemicals the way the SDS says, including segregation and temperature. Do not leave drums in a closed van in July and then act shocked at the pressure relief.

Waste is a real line item. Unused reacted foam is usually a solid you have to dispose of as construction waste under local rules. Unreacted liquid is not something you pour in the alley. Ask your landfill or hazardous-waste contractor before the first job, not after you have a half drum you cannot use.

Some blowing agents fall under federal HFC rules. If a supplier changes a formulation, get the new SDS and ask them in writing whether the blend is legal to use in your state this year. You are the contractor on the invoice. "The salesman said it was fine" is not a defense you want to test.

Grout jobs have their own paper: mix design, washout location, and a plan that does not send slurry into a storm drain. The clean crew is the one that still has municipal work next year.

How thick is a typical slab and when should you not lift it?

Many house slabs and a lot of exterior flatwork sit right around the residential code minimum of 3.5 inches, or a 4-inch driveway pour with welded wire that nobody can find later ^[1]. You will also meet 5- and 6-inch commercial slabs and the occasional 8-inch dock approach. Thickness changes drill time and how the panel bends when you inject.

Do not lift when the slab is no longer acting as a slab. If it is shattered, if joints have faulted so far that adjacent panels are independent rubble, or if the surface is already scaled to aggregate, replacement is the honest bid. Do not lift when you cannot see what is under it and the owner will not let you look. Post-tension slabs are the classic trap. Those cables are not a rumor. Drilling one is a serious event. If the building is post-tension, get drawings or stay off the slab.

Radiant heat, electrical conduit, and old plumbing sleeved in the slab are the other reason you locate before you drill. Call 811 for site utilities, then treat the slab itself as a second locate problem. A cheap inspection camera in a test hole has saved more warranties than a fancy foam gun.

Interior slabs with brittle tile need a conversation, not a sales script. The lift can work and the tile can still telegraph every old crack. Say that. Put it in the contract.

If the owner needs a new pitch to a drain, a lift that only "makes it flatter" can leave the water in a new bad place. Walk the drainage with them before you mark holes.

When is replacement cheaper than a slab lift?

Replacement wins when the panel is broken into small pieces, when the surface is already failed, when you need a new thickness or reinforcement, or when the drainage design is wrong. It also wins when access for a saw-cut and a small pour is easy and the customer wants a new look, not a patched grid.

Public sidewalks add another test. The 2010 ADA Standards say the running slope of walking surfaces shall not be steeper than 1:20 ^[10]. If your lift leaves a sidewalk steeper than the rule the city enforces, you did not finish. Some cities also have a local trip-hazard height. Confirm that number with public works before you bid municipal walk work.

Tree heave is a judgment call. If the slab is up because a root is still growing, a lift without dealing with the root is a rental on borrowed time. I would rather replace a small walk panel and cut the root with an arborist than inject under a war the oak is going to win.

Do the math in front of the customer. Lift plus patch plus risk of tile damage versus saw, haul, base repair, and a new pour. If the numbers are close, replacement is usually the calmer warranty.

What first-year paper should you keep?

Keep the signed contract, the scope, the lift targets, change orders, before-and-after photos with a tape in the frame, invoices, proof of utility locate, SDS, training records, COIs, and the mix or ratio sheet for that day. If you have employees, keep I-9s and your state's new-hire and workers-comp records. That pile is the business.

Write the scope in plain language. "Raise the three driveway panels at the garage joint toward the existing garage elevation, fill visible voids, patch holes to match as close as field conditions allow. Not responsible for existing cracks reopening or tile interior of garage." Ugly sentences prevent pretty lawsuits.

Warranties should match physics. A one-year workmanship warranty on a lift is common talk. A lifetime warranty on soil that is still washing out under a downspout is marketing. If you offer any warranty, write what voids it. Standing water from a disconnected downspout should void it.

Invoicing should match the contract units. If you bid per square foot, do not switch to "per hole" on the final bill. People notice.

For more on the insurance certificates that sit in that same folder, slab lift guide 35 and slab lift guide 47 are next reads.

How do you confirm local rules before you bid?

Call the building department for the job address. Ask if a permit is required to raise an existing driveway or sidewalk. Ask which license class they accepted on the last similar job. Ask if they want photos or a pre-pour inspection on the patches. Write the answers in the job file with the date and the person's name.

Call 811 before you drill. Then walk the site for private lines the public locate will not mark: landscape lighting, well lines, invisible fence, irrigation. Those are your problem after the locator leaves.

HOAs and property managers have their own paper. Some want a certificate of insurance naming the association. Some ban weekend compressors. Get that in email before you schedule.

If the work touches a public walk, talk to public works about traffic control and the city's trip standard. ADA running slope is 1:20 on walking surfaces ^[10]. Local inspectors may be stricter on faulted joints than on running slope. Ask.

Confirm every fee and class with the board or department that will actually stamp the form. SlabLiftPath is an independent publisher, not a law firm and not a service company. No article can promise an approval or a processing time. If a salesperson promises both, they are not the board.

Related insurance checklists that people ask for after this call are in slab lift guide 59 and slab lift guide 71.

Frequently asked questions

What is slab lift?

Slab lift is raising a sunken concrete slab by injecting grout or expanding polyurethane foam under it through drilled holes, then patching. It fills voids and moves the panel back toward the original elevation. It is not piering and it is not a new foundation. Broken rubble is usually a replace, not a lift.

How do you start slab lift?

Start with the board that licenses contractors at the job address, then an entity, a free IRS EIN, a bank account, insurance, and a written contract. Train on silica and isocyanates before you drill. Rent equipment for the first jobs if your license allows it. Confirm permits locally. Do not buy a foam rig until you can bid from yield, not from hope.

How much does slab lift cost per square foot?

There is no honest national per-square-foot number that survives contact with void depth, access, material choice, and travel. Price from estimated yield plus labor, patching, and a contingency for hidden washouts. Two 200-square-foot driveways can take very different material. Keep job-cost notes on your first 20 lifts and throw out forum averages.

Do I need a license to lift a driveway?

In many states and cities, paid concrete repair above a local dollar threshold is contracting. Florida requires certification or registration to contract unless an exemption applies. California treats unlicensed contracting as a misdemeanor. Confirm the class, bond, and current small-job threshold with the board for that address. Do not rely on a blog for the dollar figure.

Is polyurethane better than mudjacking?

Neither is always better. Foam is light, expands into odd voids, and can set fast. Slurry is heavier and can make sense in large voids when access is easy. Foam is easier to overshoot. Pick the material from soil, downtime, and the SDS you are willing to train on, not from a brand war.

How long does a slab lift last?

A lift lasts as long as the soil and water conditions you left behind. If the downspout still dumps under the slab, the void can return. Nobody has a clean national survival study that covers every soil. Write warranties that match workmanship, and exclude ongoing washout the owner will not fix.

Can you lift a post-tension slab?

Not as a casual drill-and-shoot. Post-tension cables can sit in the slab, and hitting one is a serious failure. Get drawings, use a locator method the engineer accepts, or decline the job. If the owner cannot produce information, replacement planning or an engineer is the next step, not a grid of guess holes.

What hole size do you drill for slab lift?

Hole size follows the method and the pump, not a single magic diameter. Grout ports are often larger than foam ports. Follow the equipment maker and patch so the homeowner can live with the grid. The hole pattern matters more than winning an argument about a quarter inch. Mark joints and utilities first.

Does homeowners insurance cover slab settlement?

Often it does not. Many homeowner policies limit or exclude earth movement, settlement, and wear. That is a policy-language question for the homeowner and their carrier, not something you should promise from the driveway. Bid the repair. Let their adjuster talk about coverage. Put that limit in your own contract language.

Do I need OSHA 10 to start slab lift?

Federal OSHA requires training on the hazards of the work. The OSHA Outreach 10-hour card is required by some states, cities, and general contractors, and it is optional at the federal level for many private residential jobs. Get the card if the GCs you want will not let you on site without it. Silica and chemical training still apply either way.

Can I start slab lift as a solo operator?

Yes, some people start alone on small residential panels. You still need the license your board requires, insurance, and a way to handle traffic and the drill. Foam and grout jobs go faster and safer with a second set of hands on the level and the shutoff. Solo is possible. Solo on a busy sidewalk is a bad plan.

What happens if you over-lift a slab?

You can hump the panel, open cracks, pinch a door, or throw drainage the wrong way. Foam is fast, so overshoot happens in seconds. Stop early, re-measure, and take another small shot. If you already went high, grinding or replacement may be the repair. Write a stop rule into the crew card before the first injection.

Is slab lift the same as foundation piering?

No. Slab lift injects under a concrete panel. Piering supports a footing or foundation element that is moving at depth. Selling a driveway foam job as a fix for a settling house is the wrong scope. If floors inside the house are out and doors rack, bring in someone who does foundations, or walk away.

Where do I confirm my contractor class for slab lift?

Confirm with the state contractor board and the city or county that issues the permit for that address. Ask which class they accepted for concrete raising last month. Florida uses Chapter 489 classes. California uses CSLB classifications. New York City uses a Home Improvement Contractor license for much residential work. Get the answer in writing when you can.

Sources

1. ICC 2021 International Residential Code, Chapter 5 Floors (R506): IRC sets a 3.5 inch (89 mm) minimum thickness for concrete floor slabs supported directly on the ground.
2. OSHA 29 CFR 1926.1153 Respirable crystalline silica: Construction silica PEL is 50 μg/m3 as an 8-hour TWA; employers must ensure no employee exceeds that concentration.
3. OSHA 29 CFR 1910.1000 TABLE Z-1: Table Z-1 lists a 0.02 ppm ceiling limit for methylene bisphenyl isocyanate (MDI).
4. BLS Occupational Outlook Handbook, Cement masons and concrete finishers: BLS maintains the national occupational profile and current median wage series for cement masons and concrete finishers.
5. Florida Statutes 2023, section 489.113: Florida requires certification to contract statewide, or registration to contract on other than a statewide basis, unless an exemption applies.
6. California Business and Professions Code section 7028: California law makes it a misdemeanor to act in the capacity of a contractor in the state without a license.
7. IRS, Apply for an Employer Identification Number (EIN) online: The IRS issues EINs online at no cost to eligible applicants.
8. U.S. Small Business Administration, Choose a business structure: SBA outlines sole proprietorship, partnership, LLC, and corporation choices for new firms.
9. U.S. Access Board / DOJ 2010 ADA Standards for Accessible Design, section 403.3: The 2010 ADA Standards limit the running slope of walking surfaces to 1:20.
10. OSHA 29 CFR 1926.95 Criteria for personal protective equipment: Employers must provide and require PPE where process or environmental hazards can cause injury.
11. OSHA 29 CFR 1910.1200 Hazard communication: Employers must maintain SDSs and train workers on chemical hazards in the workplace.
12. Texas Labor Code Chapter 406, Workers' Compensation Insurance Coverage: Texas Chapter 406 sets the state's workers' compensation coverage rules, including the private-employer election framework.
13. OSHA publication OSHA 3681, OSHA's Crystalline Silica Rule for Construction: OSHA 3681 restates the construction silica PEL of 50 μg/m3 and the action level of 25 μg/m3.
14. NYC DCWP, Home Improvement Contractor license checklist: New York City requires a Home Improvement Contractor license for covered residential improvement work, with a published application checklist.