Crack In Garage Foundation

Cracks In A Garage Floor: Are They A Cause For Concern?

Miranda Crace5-Minute Read
August 31, 2022

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Whether you’re a regular homeowner going about your business or interested in listing your home soon, the thought of finding a crack in the garage floor may be enough to make your stomach drop.

But don’t let some cracked concrete send you into a tailspin. Let’s breakdown the causes of garage floor cracks, when they could be cause for concern and of course, how to solve the unsightly blemish.

Know That Cracks In A Garage Floor Are To Be Expected

Due to the very makeup of most garage floors – concrete – cracks are to be expected. The good news is that a majority of the damage you’ll encounter is likely purely superficial. Most garage floor cracks don’t point to a larger structural issue or severe foundation problems and are simply the byproducts of age.

What Causes Cracks In Garage Floors?

You should expect to eventually see cracks in your garage floor partially due to the fact that there are a lot of factors working against it. Both cosmetic and more severe damage is subject to the construction and installation of your garage floor, the conditions of the weather during installation, current weather conditions, aging, shifting soil and more.

It goes without saying that most anything constructed or installed poorly is more vulnerable to damage down the road. The way your garage floor was originally poured can play a role in its cracking – what materials were used, whether or not there was underground moisture present during installation or if the ground was properly leveled can all affect how your garage floor ages.

Concrete is an understandably inflexible material and can’t stretch or bend without breaking, so things like shifting soil, tree roots and changes in the weather can lead to cracks.

When it comes to weather, colder climates can freeze the soil underneath your garage and cause your concrete to contract and expand. The more moisture present in that soil, the more significant the cracks could be.

A more serious cause for cracked flooring could also be improper water drainage from your home. If you’ve noticed pools of water, the excess moisture could be causing your soil to shift and ultimately, lead to your concrete cracks. In this case, it’s probably a good idea to investigate your drain system and make sure everything is up to snuff.

How To Tell A Control Joint From A Crack

Before you even start stressing about how to handle a garage floor crack, be sure that the damage is even worth raising some concern.

Control joints, or contraction joints, are saw-cut grooves that contractors and engineers build into concrete slabs. Control joints actually encourage cracking to relieve stress on the concrete and are probably most recognizable as the lines or ‘cracks’ that divide sidewalks into squares.

While you can’t control whether or not your concrete will crack, control joints weaken specific areas in the concrete and encourage planned, intentional cracking along their grooves – usually in straight, nonrandom lines – rather than freely across the surface of the floor.

Any cracks in your garage floor along the control joints are usually just cosmetic and are rarely indicative of greater foundation problems in your home. Most control joints will split a two-car garage into four equal sections and are about 10 – 20 feet apart.

Know A Control Joint From A Crack

The best way to differentiate between an unintentional crack in your garage floor and a crack brought on by a control joint is to look at the location of the damage and how it’s shaped.

If you find cracking along a control joint that runs in relatively straight lines, those were most likely exactly what the original installers had planned for and shouldn’t be cause for any concern.

Know What To Ask For If You’re Having A New Floor Poured

In cases where you are getting a new garage floor installed, it can be very tempting to try to DIY and save some money, especially since the cost for a concrete garage floor averages $3,500.

However, most of the money for a garage flooring project typically goes directly toward the cost of necessary materials, so it’s probably a good idea to have a professional do the installation and ensure that it’s done correctly to hold up over time.

Good contractors will also know how to use concrete slab reinforcement methods which will reduce the potential for cracking and damage in the long run. In fact, concrete that’s poured without reinforcement not only produces more cracks but also wider, deeper and harder-to-manage damage.

Here’s a rundown on the most common concrete reinforcement methods you can discuss with your contractor in order to find what works best for you:


  • Rebar: Short for “reinforcement bar,” rebar is probably the most common tactic currently used in concrete installation. These metal bars provide additional support and strength to the concrete and lessens the possibility of cracking due to tension.
  • Wire mesh: Wire mesh is another reinforcement technique which looks pretty much what it sounds like: sheets of net-like steel are placed in the center of the concrete slabs in order to provide more strength and support to the concrete.
  • Post-tension slabs: You’ll see post-tensioning less frequently in residential concrete installations, though this method still works great for any homes built on expansive soil. Unlike with rebar, post-tensioning uses steel cables instead of rods, which can more easily navigate obstructions, while still providing extra support. However, hiring professionals to install is a must for post-tensioning.

When Do Cracks In Your Garage Floor Need Attention?

We’ve already discussed instances when cracks in your garage floor are probably not cause for worry, but at what point should you take action to fix a crack in your concrete?

Here are some signs that a crack in your garage flooring may be indicative of a foundational issue:

  • There are a significant number of cracks
  • The cracks are wide and deep
  • A crack runs from your floor up your garage wall
  • Cracks are worsening considerably or rapidly
  • You live on a hillside
  • Your garage has space underneath it
  • If the concrete on either side of the crack are unlevel
  • You notice water pooling in certain areas of your garage

In these cases, it’s best to have a professional assess the state of your cement. Most DIY approaches in these instances would serve as temporary fixes rather than long-term solutions, and a contractor will know if a concrete slab needs to be replaced or if there’s potential for structural damage.

House Hunting Tip: When Are Cracks In A Garage Floor A Red Flag?

Any glaring issues with garage cracks should easily be uncovered with a home inspection. However, it’s important that you understand what some garage cracks can mean and how to identify signs of foundational damage within a home.

Here are some red flags to look out for if you suspect any structural damage in a home:

  • Difficulty opening or closing windows or doors
  • Slanted or sloping floors
  • A sagging roof
  • Cracks in drywall, siding or the garage walls

How To Repair Cracks In A Garage Floor

While some DIY home improvements should be avoided, if you’ve identified the cracks in your garage floor as superficial and not something that might require a professional’s help, a DIY fix should be able to get the job done.

When filling a concrete crack, you’ll want to make sure that you use a sealant that is an epoxy-based material or a different sandable compound, like polyurethane or polyurea. You’ll also want to avoid the temptation of cheaper but worse-for-wear concrete crack fillers – this includes water-based and latex-based options. Although many home improvement stores will carry them, these options are usually a temporary fix – they’re un-sandable, won’t allow for painting over them, and most prominently, the material will shrink with time and agitate the repair.

Here are some popular floor sealant options that are garage floor safe: 

Miranda Crace

The Rocket Homes blog is here to bring you all you need to know about buying, selling and making the most of your home. Whether you’re thinking about becoming a homeowner, selling your current home or looking to keep your place in tip-top shape, our writers and freelancers bring their experience and expertise to meet you right where you are.