AskCodeMan

Hi,

I'm working on a project in Hawaii, and we follow IBC 2006 and IRC 2006. What is the code requirement for height between the bottom of the sill plate and earth elevation? This is slab on grade application.
Thank you for your help.

Mik808 wrote: ... project in Hawaii, and we follow IBC 2006 and IRC 2006. What is the code requirement for height between the bottom of the sill plate and earth elevation? This is slab on grade application.

The answer is one building officials like to use "It depends."

That is because "it depends" on many factors - I am addressing the most common factors below.

R404.1.6 Height above finished grade addressed the absolute minimum "height above finished grade" as being 6 inches for that part of the answer to your question.
-

R319 Protection against wood decay addresses another minimum height above grade - a minimum height for wood which is not preservative treated (pressure treated) or is not a naturally durable wood species needs to be at least (minimum height of) 6 inches above finished grade (FINISHED grade) per R319.1, item 5 ... and if wood siding is to be applied, and if that wood siding extends below the bottom of the sill plate (as is common), then the minimum 6 inch height above finished grade is to the bottom of that wood siding.
-

R324 Flood-resistant construction addresses yet another minimum height above grade - this height could be much higher than the two preceding heights, all depends on any flood risk determination, if any has been determined - this would be a FEMA established level, see your local FIRMs (Floor Insurance Rate Maps) for any requirements regarding floor elevation.
-

There may be other sections which could affect the height of the sill above grade. Check with your AHJ and local FEMA regulation department (which may be the AHJ as part of their duties).

Hopefully, the above will help you determine your answer.