Garage Floor Slope – Everything You Need to Know

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You have decided to turn your dream project into reality and build your own home. For this, you have hired an architect. But while designing the blueprint of your dream house, the architect said that the garage floor would have a 0.0512 pitch.

You started wondering why do my garage floor is required to have a slope? Why can the garage floor not be straight?

In many states, while constructing the garage, having a garage slope is a must. According to the garage floor slope code, the maximum garage floor slope can be half-inch per foot.

garage floor slope code

Garage Floor Slope Code & Why It’s Necessary

Here is why having a garage slope is important.

Why Having a Garage Slope is Crucial?

People build a garage to keep their vehicles safe. But if the vehicles are damaged by stagnant liquid or water in the garage, there is no point in having a garage.

As water or liquid moves downwards, if we can build something that can move the liquid to the downward direction, this issue can be solved. And that’s how the concept of constructing a garage slope came.

If you don’t have a basement, most probably, you’ll be installing the water tank in your garage area. But for some reason, if the water tank leaks, water will be all over your garage space and damage your cars.

However, while constructing your garage, if you build a slope, water will flow out of your garage, and as a result, your vehicles will be safe.

Is There Any Specific Garage Floor Slope Building Code Recommendation?

No, there is no recommended garage slope, and IRC doesn’t prescribe any either. But the IRC recommends to construct garage slope. However, one-fourth of an inch per foot is considered a norm for garage slope. 

And in terms of percentage, this would be around 2%. Again, many constructors or architects will suggest a garage slope of one-eighth of an inch per foot. And if it’s expressed in percentage will be around 1%.  

As IRC continuously updates its building code, and the municipal building code follows the IRC, while constructing the garage, you should check the building code again.

3 Reasons Why There is No Standard for Garage Floor Slope  

As I mentioned earlier, there is no standard garage floor slope. But why is that?

1.  Different Soil Types

Soil type can vary from state to state and even sometimes from one neighborhood to another. If the soil in your area is sandy, it’s likely to shift, and it’ll require different treatment than hard soil. Again, you’ll have to consider the compactness of the soil to have a garage slope.

2.  Difference in Water Table  

Like the soil type, there is a difference in water tables everywhere. As a result, if you live in Louisiana, you’ll require a different garage slope compared to Arizona

Again, if you live in an area where standing water is a norm, you’ll have to increase the garage slope. Otherwise, the water will easily enter your garage and damage your vehicles. It’s advised to consult with a professional constructor to decide the right garage slope.

3.  Environment

Yes, the environment has an impact on the garage slope as well. For example, if you live in an area where there is snow in winter, you’ll require a different garage slope compared to garages in a warmer climate.

Because in those areas, during winter, there is frost inside the soil, which makes the soil damp. But when the summer arrives, the soil becomes hard. That means there is constant soil contraction and expansion throughout the year, which demands different garage slopes.

Practiced Garage Slope

Usually, the minimum garage depth is around 18 feet. But many constructors prefer to build a garage with having a depth of 20 to 24 feet.

If you build a garage, which has 18 feet depth, the slope per foot will be around 0.5-inch (maximum). So, the garage slope will be 18 x 0.5= 9-inches.

The 9-inch garage slope may sound a bit odd to many. But don’t worry, it’s not as steep as you think.

Size of the Garage in FeetSlope/footTotal Slope in inches 

That’s how you can measure the slope of your garage. However, if you’re planning to hire a professional constructor for building your garage, you can leave all these measuring and calculation to the professional.

Alternatives to Garage Slope

As the main purpose of having a garage slope is to drain the water, you can replace the garage slope by constructing a drainage system in your garage. However, you still need to construct a minuscule garage slope so that the water flows to the drain. 

But for constructing a drainage system in your garage, you’ll have to plan it before building the garage. Because you’ll have to install pipes and connect them with the drainage or sewerage line. You cannot add drainage in an existing garage.

That’s why it’s crucial to decide whether you want to have a garage slope or a drainage system inside the garage.

FAQs about Garage Slope

1.     How to check the garage slope?

You can easily check the garage slope by using a six-foot level. However, if you don’t have a six-foot level, you can use a self-leveling laser to check the garage slope. Check u003cstrongu003eu003ca href=u0022;linkCode=ll1u0026amp;tag=garagestoragelab1971-20u0026amp;linkId=2a9094f83af11c1060fbb6d8930920f3u0026amp;language=en_USu0026amp;ref_=as_li_ss_tlu0022 target=u0022_blanku0022 rel=u0022noopeneru0022u003eself-leveling laser from Klein Toolsu003c/au003eu003c/strongu003e. With this tool, you can easily measure the slope of your garage.

2.     Do I need a garage slope for my detached garage?

Whether you have attached a garage to your house or a detached garage, you should have constructed a garage slope.

3.     What is the recommended garage slope by the IRC?

IRC doesn’t recommend any measurement for constructing a garage slope. For better understanding, contact a professional constructor.

4.     What is the practices slope per foot for a 24 feet deep garage?

For a 24 feet deep garage, the practiced slope is around one-eighth of an inch per foot.


There is no specific guideline or fixed measure on constructing a garage slope. That’s why while constructing a garage slope, consult an architect or a professional constructor to understand what the slope should be.

Hi, I am Brent Hartman. I am a DIY enthusiast and love to improve and organize the garage in the most innovative way. I created this website out of my passion for helping people organize their garages.

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