2.1 slopes

when grading residential lots in my area the local inspection agency checks 2.1 slopes with a smart level. The reading is suspossed to be 50%. Is the 50% reading absolute or is there a plus or minus tolerance?

 

[TimPLS]

There is no such thing as an absolute measurement. Every measuring instrument ever made has a tolerance error. I don't know what that is for a "smart level" but you should ask to see the users manual or contact the manufacturer to find out what the spec's are for it.

 

[DRC1]

Grading isn't surgery. Usually if it is between 1.5:1 and 2.5:1 and the grade looks good, that is relatively uniform with no ridges or troughs and looks nice at where the slope ends, I would think that that is okay.
Hpoefully your inspector is somewhat practical.

 

[cvg]

If you look at the plans or specs, it usually indicates a minimum or maximum slope. This does not mean 1.5:1 or 2.5:1 is ok! It means that the slope MUST BE 2:1 or flatter. There are reasons for this. Yes, grading is not surgery, but engineers put minimum slopes on the plans for a reason. That reason may not be clear to the contractor or inspector, but the plans must be followed. TIMPLS is correct, there is some error in measuring with a smart level, but again, look at the specs. Grading tolerances for elevations are usually given and these must also be followed. Plus or minus a tenth is common and to check slopes, surveyor grade stakes should be set to verify the elevations.

Remember, it is not up to the contractor to determine what is "ok".

 

[gibbycu]

I agree with cvg. If a slope is constructed steeper than expected in the wrong type of soil, the built in factor of safety may not be sufficient to keep the slope in place. It's better to spend a little bit of time ( or money) getting it right the first time than spending a lot of money fixing the slope after it fails.

 

[DRC1]

I respectfully disagree to a point. One must be able to look at the problem and apply a little bit of reason. If you are building a 30 foot embankment, Slope angle is critical. (However, the minmum slope angle should be called out as a "minimum slope angle" on the plans.) If we are grading a yard so that there is positve drainage, one should stay as close to the plans as possible, but some reasonable allowance should be made as long as the work looks reasonable.

 

[sc]

Wolfcat

I am not sure if this applies in your area, but in my area a smart level is often an electronic spirit level that can give a slope reading. So if this is the case in your area I would think that it is near useless in measuring slopes on land.

Nothing beats a check by surveyors level or laser level for height differences over a given length.


Regards

sc