Flatness of a condo slab

I know slab flatness has been discussed, but I could not find anything on the forum regarding condos. I have a client claiming the floor is too uneven to lay hardwood and “exceeds industry standards”.

Does anyone have any info about the tolerances that are acceptable for a residential condo? Preferably differences in inches per foot, or over a 6 or 10-foot length. (Also, not the requirement of the flooring manufacturer, but the proper acceptable variance for the slab.)


The National Home Builder’s Performance Guidelines book indicates the a WOOD floor should not slope more than 1/2" in 20’. See page 15 section 3-3-3 here: https://builderbooks.com/media/flippingbook/pdf/rcpg_4e__contractor/r/c/rcpg_4th_ed-contractor_final4.pdf

I did not look up slabs…but feel free to do so.

Now I looked slabs up. SLABS: page 4, section 2-2-3 (3/8" in 32 ")

Most depressions and humps can be addressed with self-leveling underlayment mixes or a concrete grinder. A little prep is all that is needed to install wood, laminate, or tile flooring. Slabs are never perfect unless laser screeded.

This is very useful for single family dwellings. I will keep it as a reference. Do you have any idea where I might find similar info for a condo?

Why would a condo be held to a different standard?

Same thing I was thinkin’.

Here’s the issue: The issue here is not determining if a floor is flat enough for a wood floor installation. It is about whether or not our inspection of a carpeted condo should have determined that the concrete under the carpet was not “flat enough” to install wood floors at a later date.

I cannot find any code or requirement for flatness of a raised slab in a condominium building (fourth floor). I just find classifications that a builder can specify for the category of flatness (residential, industrial, warehouse, etc).

Client is trying to come after us for $ because we didn’t report “uneven” floors that are now problematic because they want to change the flooring. The HOA will not allow them to grind the floors, and filling low areas may cause “steps” they claim.

There are no cracks or other defects. Just variations in the slab that are conflicting with the flooring manufacturer’s requirements.

That is a latent defect …
" In the law of the sale of property (both real estate and personal property or chattels) a latent defect is a fault in the property that could not have been discovered by a reasonably thorough inspection before the sale."

Read this…

Hi Roy,

I’m not even sure this qualifies as a defect. Just because the slab does not meet the flatness requirements for a particular product does not indicate a defect. They are just choosing a product that requires a flatter surface.

They perceive it as a defect…Huh?
It’s not a defect for me . Unless you could trip over it…
What does your SOP say?

Levelness of a concrete slab per ACI is 1/4" in 10’ and that should apply to residential as well as commercial unless the commercial requirement calls for super flatness.

Do you check for it?

No. And levelness is different than flatness. I believe the ACI measurement is for level or slope, not flatness.

There was carpet present, so an evaluation of the slab by any means would not be possible without lifting the carpet.

Simply put, is it reasonable for a home inspector to determine if a slab is suitable, in this case flat enough, for a different material to be installed at a later date?

Damn! I’ve been mislead all my life…:smiley:
We don’t worry about any future date. It is NOW what we are inspecting.

having no part higher than another; having a flat or even surface.

Yes, I agree. When we all think of level, we picture a nice, flat surface. But this is a specific term that measures how flat a level surface is. A lake is level, but wind can make the surface less than flat. Likewise, a slab can be flat, but has a slope for drainage and is therefore not level.

Call it semantics if you wish, but when a lawyer is asking for money, you need to be specific.

“The lawyer made me do it.”

How can you determine the condition of the slab when it’s covered with carpet? Do I need to add another bs disclaimer?

Of course not…espectially since it was hidden under the carpet.

Exactly! Or, should we start reporting on every possible potential upgrade? Do we need to state that the foundation on a one story house isn’t adequate for a second story? Or cabinets may not be suitable for a granite upgrade? How about plywood floors on a second story, what if they want to add tile later on? Do we need to determine how stiff the plywood is?

It’s getting ridiculous.

No, not unless I feel it with my feet as I am walking.

Level is a figure of speech when a slab is expected to be level.
The flatness of a slab tolerance is 1/4" in 10’. Therefore in 10’ it is not level and not flat.
One would not notice that on a carpeted area. So I would not worry about it.

You are doing a VISUAL inspection. Installed floor coverings and furnishings, if present, prevent your inspection for other conditions without removal of the floor coverings which is outside the scope of your home inspection. Now, if as your walking through the room you find a hump or something strange you have a duty to not it in your report and recommend further invasive inspection.