Usually up 1-2 inches can be considered ok actually. I spoke to Centex foundation a few weeks ago on a property. The basic gist is that no foundation will be absolutely perfect, so there's a legitimate amount it can be off. A structural engineer verified this, so don't be scared of 1 inch off, etc. You can still use this to your advantage because most agents and consumers think any movement is bad.

The closer to 2 inches, then you may think about doing something about it. I called a few foundation companies today. They charged $300-350 per pier.

Yet another update! The owner of the foundation company explained to me that there is a measurable amount of moisture that is trapped underneath the slab when any foundation is poured. Over time the trapped moisture dries, which causes the soil to compact and crack, which causes the foundation to shift.

Foundations leveling standards are determined on a case by case basis. In this case the home was evaluated and thereby concluded that a level cosmetic appearance and structural integrity would be the determining factors when performing the contracted workmanship. The owner further stated that if any foundation is corrected to its originally intended level surface that the foundation would raise but would create voids in various parts of the house, thereby causing sagging in the foundation and could create potential for further foundation failure.

This seems to make total sense! I hope everyone has learned something from this question! Can I get a thumbs up?

2-3 inches is way too much and would suggest foundation problems. Get a foundation repair company to come out and look at or a structural engineer. I have been told that the rule of thumb is 1.5 inches and below is ok per 20ft.

1 inch is what the foundation repair guys insure.

GEESH!! Why are these getting paid what they get paid if they aren't even accurate? Atleast you can sleep better now! lol

UPDATE!!! I spoke with the seller and informed him of the initial findings. Two days later we had an appointment to re-measure with the zip-line. When I returned to the home for our appointment I found the original engineer, both sellers, and the engineer's water level in tow. I was in total surprise! He stated that his measurements where not "completely accurate"! GREEAT!!! Thanks for the crappy sleep! I think to myself! Does anybody want the name of an engineer never to use? Drop me an email. I am definitely going to yelp about this one!

Looks like you've got some great answers here. I have been told by numerous sources that FHA allows up to 2" of variation per every 16 feet. If this is correct or not, I haven't been able to personally verify.

As to why these foundations are having soo many problems can be traced to a number of issues; but the latest probable cause that I couldn't believe I was hearing was how fast these contractors HURRY the curing process. A builder the other day, told me that he really adds some kind of chemical to the foundation so that it can cure in less than 2 weeks (on a 2400 sq. ft. single level slab) !! OUCH!! YIKES! I've been told... that "es no bueno"

I like Brandon's answer. I think we often get bad pours from people who are not skilled. This could be the case if there are no cracks inside or out and no other signs such as windows that won't open, doors that won't shut, freeze boards that have popped, etc. Sometimes that can be covered up, but typically not everything can be hidden. The engineers reports I see typically not only address slope, but other observations and recommendations as well, both for inside and outside the home. I don't think I would "advise" the client one way or another. In my opinion most of us are not qualified to advise on foundation or structural issues. I'd ask the client what they want to do based on the opinions of professionals they've hired.

Have the foundation electronically measured work side by side with the professional to confirm that the home owner is not their meal ticket. Also a structual engineer is another way to go.

I pulled the following language from an engineers report done recently for a client:

IRC, 2000 Edition, Table R301.7 states allowable deformation of floors shall not exceed L/360. Although more detailed criteria may exist, this translates to 0.5” of allowable slope in 15’0” feet of horizontal distance.

So basically, less than 1/2 inch in 15 feet is generally considered not a much of a problem. I have heard the same said about 1 inch in 20 feet by other engineers. I have also had cases where slabs were not within either tolorance above, but where an engineer believed the condition was "as built" and not due to foundation movement., just questionable workmanship on the slab poor. For me, it all comes down to the level of accomplishement of the engineer and thier experience in a city. Both of these engineers use zip levels which if memory serves are supposed to be accurate to within a few tenths of an inch. Never heard of a water level. Third opinion? Good luck!

from my experience most foundations are not 100% level. the general rule of thumb is 2-3 inches across the entire slab. I have never had an engineer use a water level. the guys I use always use the zip line. just remember that any slight issue that you encounter now you will more than likely be forced to deal with when you sell. of course in austin we do have alot of clay which does cause alot of foundation problems. it is a common issue in certain parts of the city. If it were me and I really liked the house and I planned on being there for a while I would go for it. Of course it couldnt hurt to get another opinion. Most engineers will do a free verbal. I wish you luck.