How Long Does It Take to Fix a Crack in the Foundation of a House?

Cracks in your home’s foundation aren’t just ugly-they’re warning signs. A hairline crack might look harmless, but if it’s wider than a credit card or growing over time, it could mean serious trouble. The big question isn’t just how to fix it, but how long it takes to get your foundation back to solid ground. The answer? It depends. Not on luck, not on guesswork, but on the type of crack, the cause, the soil, and what kind of repair method you need.

Not all foundation cracks are the same

You can’t treat a spiderweb crack the same way you treat a stair-step crack. Foundation cracks fall into a few main categories, and each has its own timeline.

• Hairline cracks (less than 1mm wide): These are usually from normal settling or concrete curing. They’re common in homes under 5 years old. Fixing these? Sometimes you don’t need to fix them at all-just seal them with epoxy or polyurethane. That takes a day, maybe two if the weather’s damp.
• Vertical cracks (1-5mm wide): Often from shrinkage or minor soil movement. These can be patched with injection resin. The repair itself takes a day, but the resin needs 48-72 hours to fully cure before you can walk on the area or paint over it.
• Horizontal cracks: These are serious. They usually mean the wall is bowing under pressure from wet soil. Fixing these requires steel beams or carbon fiber straps. This isn’t a weekend job. It takes 3-7 days, depending on wall size and access.
• Stair-step cracks (in brick or block foundations): These follow the mortar joints and point to uneven settling or heaving. If the foundation has shifted more than 10mm, underpinning might be needed. That’s a full-blown project.

Here’s what most homeowners don’t realize: the crack is just the symptom. The real issue is what’s causing it. If your soil is clay-heavy (common in Wellington), it expands when wet and shrinks when dry. That constant push-pull moves your foundation. Fixing the crack without fixing the soil problem? You’re just painting over a leak.

Soil and weather make all the difference

In Wellington, you get rain. A lot of it. And clay soil. That combo means your foundation is under constant stress. If you’ve had a wet winter before the repair, the ground might still be saturated. That delays everything.

Contractors won’t start underpinning or excavation work if the soil is too wet. It’s unsafe. They’ll wait for a dry spell. That can add 1-3 weeks to the timeline, even if the repair itself is simple. If you’re in a flood-prone area or near a steep hillside, they’ll also need to check drainage before touching the crack. Installing French drains or regrading the yard? That’s another 2-5 days on top of the foundation work.

Temperature matters too. Most epoxy injections need at least 10°C to cure properly. In winter, if your basement is cold, they might need to use heaters or special cold-weather resins. That adds cost and time.

Repair methods and their timelines

There’s no one-size-fits-all fix. Here’s what each method looks like in real time:

Foundation Crack Repair Methods and Timeframes

Method	Best For	Time to Complete	Notes
Epoxy Injection	Vertical hairline cracks	1-2 days	Strongest bond. Doesn’t expand. Lasts 20+ years.
Polyurethane Foam Injection	Cracks with water leakage	1 day	Expands to seal gaps. Good for active leaks but less durable than epoxy.
Carbon Fiber Straps	Horizontal cracks, bowing walls	3-5 days	Non-invasive. No excavation. Reinforces wall without adding bulk.
Steel I-Beams	Severe bowing or large horizontal cracks	5-7 days	Requires interior access. May need to move drywall or flooring.
Underpinning	Significant settling, stair-step cracks, sinking corners	1-3 weeks	Excavation under foundation. Most invasive. Requires permits and engineering plans.

Most homeowners expect a quick fix. But even the fastest repair-epoxy injection-needs drying time. You can’t rush concrete or resin. If you try to paint over it too soon, the seal fails. And if you skip the inspection? You might think it’s fixed… until the crack reappears next winter.

What slows things down the most

The biggest delays aren’t the repairs themselves. They’re the stuff you can’t control:

• Permits: In New Zealand, any structural repair that affects load-bearing elements needs a building consent. That’s not optional. Processing can take 10-20 working days, especially in busy councils like Wellington City. If you don’t have one, you can’t legally complete the work.
• Access: If your foundation is under a tight crawl space or surrounded by landscaping, it takes longer to set up equipment. Some contractors charge extra for tight access.
• Hidden damage: They open up the wall and find rot, termite damage, or a broken pipe. That adds days. Or weeks. And cost.
• Weather delays: Rain delays excavation. Wind delays crane use. Cold slows curing. In Wellington, winter means slower progress.

One client I worked with thought their 2mm crack was simple. We started on a Monday. By Wednesday, we found the footer had shifted 30mm because of a leaking downpipe. The original plan? One day. The actual fix? Two weeks, two permits, and a new drainage system.

When to act fast (and when to wait)

Not every crack needs immediate action. But some do.

Call a pro right away if:

• The crack is wider than 5mm
• It’s horizontal or stair-step
• Doors or windows stick suddenly
• You see gaps between walls and floors
• Water is seeping through

You can monitor if:

• The crack is thinner than 1mm
• It hasn’t changed in 6 months
• It’s only on one wall, not all around
• No other signs of movement

Use a simple trick: tape a piece of paper over the crack. Mark the edges with a pen. Check it every month. If the lines don’t line up anymore? That’s your signal to call someone.

What happens if you ignore it

Ignoring a foundation crack isn’t like ignoring a leaky faucet. It’s like ignoring a broken leg. The damage keeps getting worse.

Over time, cracks widen. Water gets in. Mold grows. Floors slope. Walls tilt. Insurance won’t cover foundation damage from neglect. And when you try to sell your house? Buyers walk away if they see foundation issues-even if they’re "just a crack."

Worst case? You end up needing full underpinning. That’s $30,000-$80,000 in Wellington. A simple epoxy repair? $800-$2,500. The difference isn’t just money. It’s peace of mind.

What to expect during the repair process

If you’ve never had foundation work done, here’s what happens day by day:

1. Day 1-2: Inspection and quote. A structural engineer or licensed foundation specialist comes out. They measure the crack, check for moisture, and look at drainage. They’ll take photos and maybe use a laser level.
2. Day 3-7: Permit application. Your contractor handles this, but you need to sign off. Wait for council approval.
3. Day 8-10: Prep work. Move furniture, cover floors, shut off utilities if needed.
4. Day 11-15: Repair work. Injection, strapping, or excavation. Dust, noise, disruption.
5. Day 16-21: Cleanup and inspection. Final sign-off from the council. You get a certificate of compliance.

Most repairs take 2-4 weeks from start to finish. If you’re lucky and the crack is small, you might be done in 10 days. If it’s complex? Plan for a month.

How to pick the right contractor

Not all foundation repair companies are equal. In Wellington, you’ll find plenty of general builders who say they "do foundations." Don’t fall for it.

Look for:

• Specialization in foundation repair-not just "general contracting"
• License from the New Zealand Building Practitioners Board
• Insurance for structural work
• Written warranty (minimum 10 years)
• Before-and-after photos of actual jobs

Ask for references. Call past clients. Ask: "Did they show up on time? Did they explain what they were doing? Did the crack come back?" If they hesitate, walk away.

Bottom line: Time isn’t the only cost

Fixing a foundation crack isn’t about speed. It’s about doing it right. Rushing leads to failure. Waiting too long leads to disaster.

Most small cracks can be fixed in under a week-with the right method and good conditions. But the whole process, from noticing the crack to getting the final sign-off, usually takes 2-4 weeks. If you’re dealing with major damage, plan for a month or more.

The key? Don’t wait for the crack to get bigger. Don’t assume it’s "just settling." Get it checked. Document it. Act fast if it’s serious. Your house isn’t just wood and concrete-it’s your home. And it’s worth protecting.