floor level

huangyhg

floor level
i have recently been involved with a single family house where the rear was constructed roughly 1 1/2" higher than the front.  the depth of the house is roughly 30ft.  so it is fairly difficult to notice the unlevel floor walking on it, but an noticiable mistake. my question is: is there an allowable slope to an otherwise "flat" floor in wood framing?
to my knowledge the only requirements for "flat" or "level" concerns stairs. exterior porches and decks are often designed & constructed with a lot more slope than that to shed rain water.
thank you.
i think i should ask this another way.. i have been asked to determine how much we must lower the rear wall to bring the floor within an acceptable tollerance of being "flat".  maybe lower the wall by 3/4" in lieu of the full 1 1/2".
i would be more worried about the overal house.  spring height wont be the same.  if you are using roof trusses, the joist wont be sitting at the same elevation.  
what if you use hacked plate on the top of the foundation?  i dont know who to blame but if i were the framer, i wouldnt want to build on uneven foundation.
this is a walkout basement with unlevel plate due to the stud lengths. and yes many many discussions have been had about the distress the rest of the house would have.  this is why i'm trying to determine how little we would have to lower the wall (if at all) to make the floor "level".  i'm hoping to find something like a max slope or max difference in elevations of a floor joist bearing locations.
before doing anything, suggest that you get a high precision cross section of the entire floor to make sure the slope is uniform. with construction that poor, the floor may have "waves" in it that would be best to know about sooner rather than later.
*i think i should ask this another way.. i have been asked to determine how much we must lower the rear wall to bring the floor within an acceptable tollerance of being "flat".  maybe lower the wall by 3/4" in lieu of the full 1 1/2".
to change the floor level 3/4" or 1.5" should not be significant in terms of difficulty and cost. it feels simpler to jack the lower side of the house. but if budget is a limit (typical), then the easiest solution is install a level subfloor or pour a lightweight grout subfloor which will level itself. yes, this will leave all the door and window headers at different levels. old house blues.
i'm assuming that this house is still under construction without china cabinets in place..
like dzinegrp mentioned, i'd recommend jacking in lieu of cutting. why? the condition appears to be at the foundation. if you start chopping on the concrete, you will loose your minimum cover and then durability of the reinforcement becomes an issue. not to mention rust stains and spalling.
why do i say it's the concrete and not framing? framers and carpenters use levels, and the lumber is all the same length from the supplier for studs- or if they have to cut to length, only a couple at most can be cut at a time, so it would be noticable if they screwed up a cut mark..
finally, how much- well, if you are going to attempt a repair, the difference between 0.75 inch and 1.5 inches is nill as far as material goes, infact, you might spend more to get the 0.75 inch because of the labor involved in shaving a 2-by in half introduces additional labor expense for the shims.
but on the flip side, if your anchor bolts are too short, you can't do that. so what about a float layer (gyp)? well, you might exceed the design capacity of the floor system and the you are really up crap creek.
or you could do nothing, although 1.5 inches in 30 feet is only l/240, you could probably watch a bowling ball roll down the hallway before the carpet is put in. i'd fix it- and fire the surveyor.
thank you all for your comments.
jen4950 - my first thought was the foundation wall as well for all the same reasons you mentioned.  however, i have surveyed the entire house and found it is in the length of the studs at the walkout level (not a typical stud height).  and yes slideruleera, the framing was very poor and it is not a consistant 1 1/2" off, but close enough to try and find an answer to my quetion about floor level tolerances.  
also, we looked into using a self leveling pour, but the height of 1 1/2" brings the floor above the botto of the door.  
and we don't have much access to the front of the foundation to jack it higher.
so far the solution is to support the main floor joists while the walkout level studs are cut to dropped the rear of the house.
if the house is already roughed in, the windows set and the doors hung; there are fewer options to consider. jacking the 'low' walls verses lowering the 'high' walls: along one axis you're ok, along the other axis you are creating unacceptable problems regarding the windows and doors (square/plumb/level). if true flatness is expected, a self leveling floor topping is the most reasonable approach. the door bottoms can be trimmed to accomodate an acceptable correction.
labor represents less than 10 dollars/square foot on framing a residence.  disassembly and reconstruction should add approximately 15-18 /sq foot to the cost.  what is the value of an poorly constructed and repaired house vs. a correctly framed one?