Floors out of level - do your sloped floors need attention - Where to begin - Bedroom with hardwood flooringMost homes eventually will have floors out of level with the passage of time, but they shouldn’t feel like The Mystery Spot. How much sloping or crowning is too much? What should be done about it? And most importantly, what is the cause of it?

In Belwood, Belgatos, Surmont, and nearby, having issues with unwanted slopes is not unheard of, unfortunately. Most of Los Gatos close to the hills can experience foundation and drainage issues that result in floors that aren’t flat. But those aren’t always the causes.

What causes uneven floors?

A number of causes can make floors out of level. Often it’s related to water, weight, and soil.

  • Water Leaks: Tub or shower water that gets under bathroom flooring can cause the particle board or plywood underneath it to swell, making the floors squishy feeling or unlevel. That shouldn’t be ignored, as water damage can lead to things like mold, fungus, and dry rot.
  • Rain or Ground Water: Sometimes hardwood floors get cupped and unlevel when there’s moisture in the crawl space below. A couple of our clients saw buckling floors begin to flatten out on their own after they sealed their crawlspace against groundwater intrusion. (The moisture could have several possible sources, or a combination of them. All sources will need to be addressed.)
  • Excessive Weight: Excessive weight can wreck havoc, too. A home’s components are designed for a particular load, but if that area is overweight, there can be bowing beneath it.
    • For example, a client who is also a contractor pointed out cracked tiles in a bathroom floor and remarked that the room was probably designed with a lightweight vinyl floor and when home owners upgraded, they installed tile without additional support in the crawl space for the extra weight.
    • A similar result could happen if a house was designed for a lightweight roof and later on a heavier one, such as concrete tile, was added without structural reinforcements.
    • You might see this in other parts of the structure as well. We frequently see framing around garage doors sag across the top when occupants store heavy items in the garage attic area, which is not built for it – the span from one side of the garage to the other makes it prone to sagging if weighty things are stored in the middle.  Drive down almost any residential street and you are likely to see at least one or two droopy garage door frames across the top.
  •  Foundation Movement: Foundation issues can be especially costly to rectify.
    • Foundation problems often are related to water mixing with expansive clay soils (this type of soil expands when wet and shrinks when dry) , so foundation and drainage work often go together hand in hand. (See this helpful video from Bear Engineering for more info.)
    • Tree roots and erosion can also cause problems with foundations, and those may result in uneven floors, too. (This is not an exhaustive list.)
    • Flooring can also go out of level due to additions to the home and uneven settling between the new and old footprint of the home. Clients of ours in this situation chose to replace the flooring (which was worn anyways from active use and settling) and have the installer use a leveler before installing the new material.


Isn’t settling normal?  When should we be concerned about floors out of level?

Homes do settle, particularly when they are first built. Ideally, that settlement would be even, and the entire structure may sink into the soil by the same amount. If your floors are out of level enough to be bothering you, pay attention. Is it just one spot? Is it somewhat even, is there a pattern to it?

Floors out of level - few things to check, consider a floor level surveyIf your abode is not settling evenly, or if the amount is more than a little bit, it might be time to have a closer look at house the structure is performing generally.

Are windows or doors sticking, or stiff and difficult to open or close?

Are there diagonal cracks in the walls? (Often these are spotted at doors or windows.) Are wall cracks greater than 1/8 of an inch?

Are there noticeable dips or humps in the floor? Is there cupping, or worse do they feel “spongey”?

These are all potential red flags.

How much slope in floors is acceptable?

I have attended many home inspections and quite a few foundation inspections, and there does not appear to be one set standard that is universally accepted for when floors out of level must be corrected.

Some inspectors quote an amount out of level that is in tolerance per year of the structure (x inches over y feet for every z number of years). Others state that 1 inch (or 1/2″ or 1.5″) over 20 feet is acceptable, but at 2″ there is a problem.

The best person to speak about with this is a structural engineer, probably someone who focuses on foundations. Of course if there’s another issue that could be making it worse, or putting you and your home in danger, such as water intrusion or tree roots, that should be taken care of!

How are measurements done for floors out of level?

Floor level survey results may be by hand or typed
If you’ve ever put up a framed piece of artwork on the wall, you may have employed the use of a bubble level to make sure that you weren’t hanging it crooked.

Those kind of bubble levels are too small for measuring a home’s flatness (or lack thereof), but it is a similar technology – a device with fluid in a hose that gets spread around the home by a structural engineer or foundation inspector (if anyone else also does this, I’m unaware of it) to check for deflection. The device used is called a manometer.  Measuring for evenness is called a floor level survey.

The floor level survey is often done as part of a foundation inspection. If there’s a crawlspace or basement, the inspector will go through those areas also, noting any issues with the foundation such as cracks, spalling, piers out of plumb, exposed rebar, and other things that homeowners may not be aware of.

Most of the time, the inspector will sketch out a floor plan of the home on grid paper, and then will manually write in the number or fraction of inches. A spot is chosen to be the baseline or reference point, and everything else is measured against it.

In the image to the right, this client had a floor plan available, so the inspector typed in the readings when done (at the office, not on site). The lowest area shown is -.5 and the highest is .3, so the range is 80% of an inch for this area.

Please note that some of the numbers are positive, and others are negative. These are in  reference to the baseline spot chosen. Some areas are higher and some lower than that corner of the house.

What can be done about uneven or sloped floors?

The plan of action on correcting the sloping floors will depend on what the cause is. Inspections can be crucially helpful in figuring this out.

If the problem is a leak that is causing the nearby floor to crown or sag, once the leak is corrected, the floor will probably need to be replaced and new underlayment put down. That’s pretty straightforward.

If the load is too heavy, as with the tile floor where a lighter material previously had been laid, you may need a contractor or engineer to figure out whether additional supports or jacks are necessary, and if using jacks and raising the floor would fix the sag or cause unintended, negative consequences. There’s no one-size-fits-all for this situation.

If the floors are out of level in many places, and you have sticking doors or windows, or cracks in your walls, it might be time to have a foundation inspection done as this seems like it may be more substantial. There could be horizontal cracks in the foundation, or a soils issue that would benefit from underpinning, or any other number of possible remedies for floors out of level. The specialist will need to see, measure, and evaluate to get you that info.

Sometimes even after repairs are done, the floors still aren’t flat, for instance, if there’s a hump in the floor. A contractor should be able to come in and do repairs to level it.

In some cases your contractor may say that the floors out of level are not a big enough deflection to be significant, but you are bothered by them and want to make a cosmetic improvement. In those cases, you may want to consider a floor leveling compound or self-leveling underlayment. Hardware stores have many of these to evaluate. The compound is cement based and heavy, so it would not be wise to use this in big areas with large differentials. Think small and cosmetic only.

Finally, many foundation repairs do require permits and finals in Los Gatos, including horizontal foundation crack repairs, but not all do. When in doubt, call the town’s building department and ask.


Floors out of level – related reading

What To Consider When Buying a Hillside Home in Silicon Valley (from our Valley of Heart’s Delight blog)