Minimum Foundation Wall Height above Grade Code confusion

Question

Minimum Foundation Wall Height above Grade Code confusion

jacky89 (Civil/Environmental)

(OP)

22 Jul 19 15:55

CRC 2016 R404.1.6 says minimum height above "finished grade" is 4" for masonry and 6" for concrete foundation walls.
CRC 2016 R317.1(5) says preservative treated wood siding, sheathing and wall framing on the exterior of a building is required when clearance is less than 6 inches from the ground or less than 2 inches measured vertically from concrete steps, porch slabs, patio slabs and similar horizontal surfaces exposed to the weather

R317.1 seems to indicate that the top of foundation can be minimum 2" above concrete and hardscapes. I can't think of any case where non p.t. wall framing and sheathing can be 2" from the ground therefore it seems these two codes are conflicting.

What is the code definition of "finished grade"? Does that mean soil surface or any surface including finished concrete?

oldestguy (Geotechnical) · Answer 1 · 2019-07-22 16:06:44

In some areas there are wood-eating ants and other such bugs. They best need the earth right up to the siding. However, by having some clearance their open travel height ease of climbing is made more difficult. So above concrete it is in area where less ants may live, requiring less heights.

jacky89 (Civil/Environmental) · Answer 2 · 2019-07-22 22:55:18

I understand the termite concern but I'm questioning what is the code definition for "finished grade" because there seems to be a conflict in the two codes.

jacky89 (Civil/Environmental) · Answer 3 · 2019-07-24 16:19:51

RE: Minimum Foundation Wall Height above Grade Code confusion

jacky89 (Civil/Environmental)

(OP)

24 Jul 19 16:19

anyone?

CarlB (Civil/Environmental) · Answer 4 · 2019-07-24 16:57:29

I'd think Finish grade is same as Grade, which is defined:
[RB] GRADE. The finished ground level adjoining the building at all exterior walls.
I'm only guessing, but think the R317.1(5) is not meant to apply to concrete block or concrete foundation tops, rather other wood items such as sheathing. E.G. are other foundation types allowed, such as All Weather Wood?

coloeng (Civil/Environmental) · Answer 5 · 2019-07-25 16:12:38

you usually place hardscapes, i.e. concrete patios, steps, etc. above finish grade therefore the two codes don't conflict.

jacky89 (Civil/Environmental) · Answer 6 · 2019-07-26 02:19:23

So concrete surfaces and other hardscapes are not considered finished grade? I just haven't seen an official definition of what finished grade is.

MotorCity (Structural) · Answer 7 · 2019-07-31 16:07:52

Finished grade is finished grade......whatever you step on......concrete, soil, alligators, etc

civilman72 (Civil/Environmental) · Answer 8 · 2019-08-06 13:58:45

Finished grade from a design standpoint is what you step on.

But finished grade for this code is dirt, or final backfill material that's placed against the concrete foundation wall. As others stated, it's not concrete, asphalt, or other hard surface materials.

jacky89 (Civil/Environmental) · Answer 9 · 2019-08-13 08:26:33

But where does the code describe what they mean by finished grade? It's too unclear.

wikidcool (Structural) · Answer 10 · 2019-09-07 00:27:59

I hate it when sections contradict each other. I think it's generally accepted that finish grade is whatever surface you step on after construction is complete. BUT, exact word choice aside, I think the intention here for R404.1.6 is to have concrete or masonry foundation and retaining walls extend 4"/6" min above the adjacent DIRT, if there is any. I think "soil" would have been the better choice of words here than "finish grade". I would not consider this requirement to apply where the grade next to the wall is an impervious surface like concrete.

bimr (Civil/Environmental) · Answer 11 · 2019-10-01 23:09:15

Finished grade means the surface of the ground after completion of final grading.

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