Foundation Adjacent Grade Tolerance
Foundation Adjacent Grade Tolerance
(OP)
Our soils report recommends at least 10% for 10 feet perpendicular to the foundation walls. If compaction was done to at least 90% ASTM D 698, how much tolerance in grade differential from 10% is the standard of care when examining these grades 7 years after construction?
Potential movement of the soil up at the foundation wall interface location, movement of soil at the toe location of the 10% envelope, or movement at both locations can affect grade, or together effectively cancel out a net change in grade over the 10 feet.
The site soils are sandy clay.
Potential movement of the soil up at the foundation wall interface location, movement of soil at the toe location of the 10% envelope, or movement at both locations can affect grade, or together effectively cancel out a net change in grade over the 10 feet.
The site soils are sandy clay.





RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
What is your purpose in posting? Plese explain little of the site situation and perhaps a question then. It looks like you are replying to something somewhere.
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
Are you saying, by stating only the typical 0.1' survey measurement tolerance in your response, that the settlement should be negligible if grading and compaction was done per those soil report recommendations in the OP at original construction for a clayey sand material?
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
cvg has explained possible tolerance standards, but what is your purpose now? Has the site changed due to settlement or work since and are you trying to relate it to a 7 year old job? ? Is there some drainage problem? What does the local code require, if there is a local code? After 7 years is someone trying to claim damage due to something done 7 years ago? Has there been some possible site grading change after the original job, such as plants removed or planted? If so, good luck. 10% may be nice for drainage, but perhaps other factors make that not possible, such as paving or walks. That's darn steep for walk ways in some situations.
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
Again, you have not indicated if this building is on fill or cut, which might make a difference. And have you verified that the material is actually clayey sand as indicated in the geotech report?
10% is steep and some erosion should be expected. I would normally expect to see no more than about 5% slope away from a foundation.
RE: Foundation Adjacent Grade Tolerance
RE: Foundation Adjacent Grade Tolerance
The amount of settlement around the foundations is variable, almost always worse at the front door porch (Murphy the Engineer). This influence fro Murphy, PE can have grave consequences for basement height backfills.