Commercial Site Surface Tolerances

[GoldDredger]

Does anyone specify the tolerance for final paving elevations for a typical commercial site (internal parking and drives)

I was discussing it with our survey department, and indicated I would like to specify finished pavement elevations to within 0.03'. They indicated that was too precise, and 0.05' would be more reasonable.

Undoubtedly the FF elevation of the building should be spot on, but parking lot grading could probably fluctuate a bit without causing too much problem (except in particularly flat areas, where precision to meet minimum slope might be needed).

Anyone have an opinion on that?

 

[sammyk]

We specify +/- .05' on our parking lots.
But in most cases you'll get much larger fluctuations.

The paving contractor has to spend time looking at your plans trying to find your drainage intent based on the few spot grades you give. And I guarantee no one puts as many spot grades as a contractor would like or your plans would be illegible.

Once the curb is in, the agg. base will be placed to grade based on the contractors evaluation of your plans. The real trick is having a good paving contractor to make sure the lot drains. A good contractor can evaluate better than you what field adjustments are needed based on as-built shots of curbs and structures.

I would place the +/-.05' on your plans, for your own liability. But you should keep in mind that it probably wont be met, and that the goal is to make this thing drain.

Even the FF should have a small tolerance or youll get bids for an exhorbitant amount seeing how the contractor will have to price an extra amount of liability.

 

[dik]

I usually use 0.10' with a note to the effect that it has to drain. I also show drainage arrows.

Dik

 

[cvg]

better bet is to specify minimum 2% and preferably 4% slopes for areas which must drain. Anything flatter than that will end up with bird baths due to inaccuracy in the grading and paving and staking

 

[Hoagie]

You need published data from a reliable/conventional source. The US DOT and USACE have dimensional quality control for all sorts of items/materials.

 

[SlideRuleEra]

Concur with cvg.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[civilperson]

0.5% for PC Concrete and 1.5% for HMA are the lower limits of accuracy without paying a premium.