Thin shrinkage cracks and uneven color in the first weeks are normal. Ponding water, a crumbling surface and wide or uneven cracks are not. Here is how to tell them apart and what to do under California's contractor rules.
Why is my new concrete already cracking? Is the contractor responsible for a crack that appears weeks later?
Concrete shrinks as it dries, and that pulls thin cracks into it during the first weeks. Joints are meant to catch them. Is the contractor responsible? It turns on the cause and the contract. A hairline crack is generally accepted in the trade. A crack that is wide, stepped, or clearly due to missing joints, a soft base or early loading is a workmanship matter. Photograph it with a coin for scale, note the date and write to the contractor.
Why does my new concrete have dark and light patches?
Dark and light patches come from the slab drying at different rates. In Oakland a part shaded by the house or a tree, or kept damp by fog, stays darker for weeks. Other causes are a second truckload from a different batch, water added on site, and plastic sheeting touching the surface during curing. Give it two or three months. Most blotches fade. Any that remain are a matter of looks, not strength.
What happens if it rains on fresh concrete?
Timing decides it. When it rains on fresh concrete before it has set, the water weakens the top layer and can leave it dusty, pitted or prone to flaking. After the surface has hardened, usually several hours on, rain does no harm. Our rain comes mostly between November and March, so winter pours are booked around the forecast and covered if a shower arrives early.
The finish has footprints, rough spots or a wavy surface with low spots. Do I have to accept it?
No. Footprints, drag marks and birdbaths that hold water are finishing errors. Run a hose over the slab and photograph where water stays after ten minutes. Small rough patches can be ground. A low spot may need a bonded topping or that panel replaced. Send the photos to the contractor with a written request to correct it before you make the last payment.
Are control joints really necessary? My contractor says he will saw-cut them a week later.
Control joints are necessary, and a week is far too long to wait. They are planned weak lines that tell the slab where to crack. Saw-cut joints need to go in as soon as the concrete can be cut cleanly, which is normally within the first day. After a week the slab has already chosen its own crack lines. Ask for joints to be tooled during finishing or sawn that day or the next morning.
I found out my slab was poured without rebar or mesh. What should I do?
Read the contract first. If it specified steel and the slab was poured without rebar or mesh, the job does not match what you paid for, and you should say so in writing right away. If nothing was specified, you have less to stand on. Plain concrete on a good base can serve as a patio. On clay, on a slope or under vehicles, a slab without reinforcement is more likely to separate at its cracks. Keep your photos and any delivery tickets.
My new stamped concrete is slippery. Can that be fixed?
Yes. Stamped concrete turns slippery when a glossy sealer is applied without a grip additive. The cure is to recoat with a sealer carrying fine grit, or to strip and reseal if the film is too thick. Ask for this before winter, especially on a slope or steps.
Why is my stamped concrete fading, cloudy or peeling?
A cloudy or white sealer means moisture is trapped under it. That happens when sealer goes on too thick, on a damp slab or on a foggy morning. Peeling follows from the same cause. Fading is the sealer and surface color wearing in sun and traffic. A cloudy film can sometimes be reflowed with solvent. Otherwise it is stripped and resealed in thin coats on a dry day.
The surface is flaking within the first year. Whose fault is that?
Flaking in the first year or first winter points to how the slab was placed, since Oakland does not get the hard freezes that cause it elsewhere. Likely causes are excess water, finishing too early, rain on the wet surface or no curing. Raise it in writing with photos. The usual repair is to grind and resurface, or to replace if the weak layer runs deep.
It was poured in extreme heat and now it looks bad. Is it ruined?
Not always. Concrete poured in high heat and dry wind loses surface water quickly, which causes a web of fine cracks, a rough finish and uneven color. Oakland is seldom very hot, but offshore winds in September and October dry a slab fast, and the inland valleys do reach high temperatures. Fine surface cracks are mostly cosmetic. Deep or wide cracks, or a weak dusty surface, should be inspected.
The stamped pattern is crooked and uneven, and I still owe the final payment. What are my options?
Put the defects in writing before you pay or withhold anything. List each one with photos and ask for a correction plan and date. California's Contractors State License Board says payments should not get ahead of the work completed, so holding back a part of the final payment that matches a real, documented defect is reasonable. Withholding everything over a minor flaw tends to end in a dispute. This is general information, not legal advice.
The crew left ruts in the lawn, washout and splatter. Should they fix it?
Yes, unless your contract says otherwise. Ruts, concrete washout dumped in a bed and splatter on walls or a neighbor's fence are damage, and a careful contractor repairs them. Photograph them before anything is cleaned. Splatter comes off most easily in the first days. In Oakland, washout must also be kept out of the street gutter and storm drains, which lead to the creeks and the bay.
My new pad is out of level, and the forms were left on and are stuck. What now?
First check what it was meant to do. Outdoor slabs are built with a slight fall so water runs off, so a patio that is out of level by design is correct. A shed or hot tub pad specified as level should be level. Put a long straightedge and level on it and note the gap. If it is off from the agreed plan, ask in writing for it to be corrected.
For the forms, ask the contractor to come and strip them. Wood forms are normally pulled within a day or a few days. Left longer, they swell and grip the concrete, and prying them off can chip the edge. They can still be removed by cutting the stakes and working the boards loose with care. Wood left against a slab also holds moisture and attracts termites.
What can I do if the contractor will not come back to fix it?
If the contractor will not come back, send a dated letter or email that lists the defects and sets a reasonable deadline. Then:
- File a complaint with the Contractors State License Board at cslb.ca.gov or on 800-321-CSLB (2752). The board accepts complaints for up to four years.
- Ask about the board's arbitration program, which is mandatory for disputes of $25,000 or less.
- Look up the contractor's licence bond on the licence record.
- Use small claims court for smaller sums.
- Get a second contractor's written opinion of the defect.
The board says plainly that filing a complaint does not guarantee you will be paid.