How Much Floor Slope is Acceptable?

Floor slope is quite a common issue among old houses, but it is something of concern when purchasing new homes. It is also an important issue when building or renovating houses. Certain levels of slope in the floor are acceptable, while some could be dangerous. If you find uneven surfaces on the floor, check the level to identify whether it indicates some major issue. If you are not sure about the situation in your house, contact a flooring specialist to find what is acceptable floor slope in your case.

floor slope

How to Identify a Sloping and a Sagging Floor?

If you identify that the floor is angled in one specific direction, then the floor is sloping. But a sagging floor is uneven on all sides. A house could have both a sloping floor and a sagging floor. However, they are two separate issues. The following signs are most likely to give away a sloping floor.

  • Doors and windows stick out, causing difficulty in opening and closing them.
  • There could be water puddles in your house forming in a specific area at the lowest level.
  • If you notice recent shifting or cracks in ceramic wall tiles, it could be a sign of a slanted floor.
  • Visible diagonal cracks on walls from the corners of the door or window frames towards the ceiling also indicate a structural issue.

How to Measure the Floor Slope?

The best way to check whether your floor is angling is to check it with a level. Place the level on various places on the floor and see whether it is in level. If you find that the floor is not level, you need to find how much slope it has and its direction.

You can measure the floor slopes using torpedo levels, digital levels, and also some smartphone apps. Use a tape measure to check the unevenness. Measure from one corner to another of the room. Check this in a few places and see whether there are any differences. You can also check it with a small ball with a smooth surface or a marble. Place the ball in different places on the floor and see whether it moves. If it seems to move downhill, then you are sure to have a floor slope. 

You can also use a laser level that uses a laser beam to determine the slope more accurately. It is useful in finding the level to mount items on the wall without having to check by sight. The laser levels are easy to use, and you can read the readings yourself.

Reasons for Sloping Floors

There are various reasons for sloping floors, most of them being damage to the structure. The following issues could be the possible reasons behind this issue.

Foundation Settling

The soil under the foundation can compress over time, causing the foundation to sink slowly. This is not noticeable at first but becomes more noticeable as the floor sags and slopes. This is the most common cause and also the most difficult one to fix. The solution includes lifting up the foundation to level the floor. You should get the support of a professional to fix foundation shifting.

Damaged Floor Joist

The floor joists are the beams that run perpendicular to the ceiling joists to support the floor. Damaged floor joists may not provide the required support and cause the floor to sag. The main reasons behind this are water damage, mold, and pests. 

Poor Floor Installation

Uneven floors are also a result of poor installation with unleveled subfloors and floorboards. So, when getting the work done, make sure that the contractors do not work carelessly and rush the process. If you find that your floor installed recently is sloping, contact the company and ask them to fix the issue. Always get house renovations done by a reliable company with positive feedback.

Ground Shifting

If there was a recent change in the ground around the house due to some excavation or construction, it may cause the house to settle. It is not something that you can fix yourself. So, get a professional to examine the situation and recommend a remedy. 

What is an Acceptable Floor Slope Level?

what is acceptable floor slope

The acceptable floor slope level might differ with the opinion as some people find it acceptable for the floor to have a slight slope. However, some others need the floor to be at a proper level. According to most standards, the floor slope of less than ½ inch per 20 feet is acceptable. Measure the slope from one end to another of the space and check whether it suits the value stated here. Nevertheless, it is important to have the floor as level as possible. Uneven floors cause various issues including difficulty in closing doors. A slight slope is not a big deal, as there are almost no floors with perfect levels. 

Signs of a Major Concern

Sometimes, you may not identify the floor slope unless something obstructs the usual way of the house. This often comes as inconveniences in opening or closing the doors. Here are some signs that a sloping floor has become a major issue in the house. 

Cracks in Walls and Ceiling

You may find cracks in the foundation, ceiling, or walls as a result of the sloping floor. But it could also be due to some other structural problems. 

Doors and Windows Sticking Out

The doors and windows refusing to open or close properly is another thing that you will notice. It is usually due to the uneven floor causing stress on the door frames. Check the possibility of debris collected around the door or window before concluding that it is a floor-level issue.

Slanted Walls

Walls leaning to a side is another visible problem due to floor sloping. However, it may also be due to some other major foundation issue. Take immediate action in case you see any slanted walls in the house.

Can You Repair a Sloped Floor?

You can repair a sloped floor through expensive foundation work. The other option is to level the floor on the foundation to avoid damage to the doors, windows, and walls. This is the simplest and most convenient way. It only requires new subfloor installation. If the problem is with floor joists, get a professional contractor to repair that. There are a few methods of repairing a sloped floor:

  • Replacing the floor and subfloor which is a less invasive method. But it is quite expensive than other methods.
  • Replace the whole foundation if it is a major issue that cannot be solved in another way. 
  • The next option is to replace the wooden joists or sills. It is a complicated process that requires manipulations of structural support.
  • You can also shim the floor, which is one of the most common methods. It is relatively simple and requires putting shims under the floor joists to level them.

Frequently Asked Questions

How Much Floor Slope is Noticeable?

Usually having a slope of about ½ inches or less for 20 feet is not an issue. But having a slope of greater than 1 inch per this distance could be a problem. Floors with a slope of 2 inches or more for 20 feet will be a major concern as they will give away signs.

Should I Buy a House With Sagging Floors?

You need to be more concerned when purchasing a house with sagging floors. The slope of the floor may be a minor cosmetic issue or something else. It could indicate water damage or major issues with the structure or foundation of the house. Consider the age of the house in making the decision. If the house is relatively new (within 5 – 10 years), it may indicate a bigger problem.

How Much Floor Slope is Too Much?

The amount of slope you consider too much varies with the type of flooring. Hardwood or tile floors need to have more level than floors with carpets. Consult a professional to find the proper floor level in your case.

How Much Does It Cost to Fix Sloping Floors?

The normal cost for repairing sagging floors will be between $1000 and $10,000. The average rate of fixing this is around $300 per square foot. If you are looking for leveling the floor, it costs around $3 – $5 per square foot. So, this will cost something between $300 and $500 for an area of 100 square feet.

How Do I Know if My Floor is Sagging?

Moist and rotting wood infected with mold is the main reason behind the sagging floor. You can identify it easily with skewed or unleveled door and window frames. Sagging, uneven upstairs floors, cracks in the interior drywall, and sinking crawl space support also point to this issue. In addition to being very unappealing, sagging floors can be dangerous since there is a possibility of collapsing if not fixed soon enough. 


Now you know how to identify the floor slope and fix any related issues. Make sure to avoid any activities that cause structural damage leading to tilted floors. Although you can fix these problems, it is always better to identify them early. It is also cheaper to fix minor issues early before they cause bigger problems. Follow the preventive measures to keep it from happening again.