Interior Loadbearing Wall

[Uncle Bob]

I can't find in the 2009 IRC, the requirements for a footing below an interior loadbearing wall. It's 5 pm and I'm brain dead. Help please with code section or that I am wrong in believing a footing is required below a slab foundation for an interior loadbearing wall.

Thanks,

 

[pwood]

404.1.5.3 would work. 403.1.4.2, 403.1.6. or 403.1.1 , figure 403.1(1)

 

[97catintenn]

I wasn't aware that a continous footer was required below an interior load bearing wall.

 

[mtlogcabin]

R403.1.4.2 Seismic conditions.

In Seismic Design Categories D0, D1 and D2, interior footings supporting bearing or bracing walls and cast monolithically with a slab on grade shall extend to a depth of not less than 12 inches (305 mm) below the top of the slab.

Now if you are not in a seismic zone

R403.1.6 Foundation anchorage.

Sill plates and walls supported directly on continuous foundations shall be anchored to the foundation in accordance with this section.

Wood sole plates at all exterior walls on monolithic slabs, wood sole plates of braced wall panels at building interiors on monolithic slabs and all wood sill plates shall be anchored to the foundation with anchor bolts spaced a maximum of 6 feet (1829 mm) on center. Bolts shall be at least 1/2 inch (12.7 mm) in diameter and shall extend a minimum of 7 inches (178 mm) into concrete or grouted cells of.....

How do you get an anchor bolt to extend 7 inches into the concrete if you do not have a footing? Remember the J-Bolt should be a minimum 3 inches from the earth just like the rebar. That is a minimum 10 inch thick footing.

 

[97catintenn]

I wasn't thinking...sorry. I confused myself with the non-load bearing walls being placed wherever we wanted to on the concrete slab.

 

[Rio]

How do you get an anchor bolt to extend 7 inches into the concrete if you do not have a footing? Remember the J-Bolt should be a minimum 3 inches from the earth just like the rebar. That is a minimum 10 inch thick footing.[/color]

Not to be nitpicky but as the 10" A.B. is sitting on top of a 1-1/2" sill plate, has about 1" (probably more) above that for the nut and washer, has a 3-1/2" slab to go through before reaching the footing that would leave 4" extending down below the bottom of the slab, requiring a 7" footing to achieve 7" minimum embedment while having 3" of cover between the bottom of the A.B. and the dirt. If I'm not mistaken interior footings can be measured from the top of the slab so the minimum 7" embedment would be in compliance in this scenario.

 

[Sifu]

I hadn't thought of the bolt embedment as a way to provide a specific code section for interior slab/footing thickness.....but I like it. I use this:

R401.2 Requirements. Foundation construction shall be

capable of accommodating all loads according to Section

R301 and of transmitting the resulting loads to the supporting

soil. Fill soils that support footings and foundations shall be

designed, installed and tested in accordance with accepted

engineering practice. Gravel fill used as footings for wood

and precast concrete foundations shall comply with Section

R403.

·:·In order to fulfill its role in the complete load path, the

foundation must support the required design loads and

transmit these to the soil. The phrase "accepted engineering

practice" in this section means common practice

that is acceptable to the code official of the

jurisdiction.

Often, the slab has been poured before I realize there is a load bearing wall above it (I know, but I'm not allowed to require plans!) so when I get there it usually results in a phone call to the mayor and an engineer!

 

[mtlogcabin]

Rio

You are not nitpicky. I have always measured from the top of the slab to the bottom of the footing for the total depth of the footer in a mono slab foundation pour. It was my poor choice of wording. I should have stated 10 inch thick concrete, not footing for clarity.

 

[Keystone]

Below was a foundation plan submitted and rejected, the engineer inadvertently listed anchor bolts at 8". Recieving this type of thing more often lately.

 

[Keystone]

Where's my pic, have to figure this out

 

[Daddy-0-]

I like the section listed by SIFU. You need the 7" for the anchor bolts, BUT that might not be thick enough to support the imposed load....(think PSL or pipe column point load). Without a slab set up you could use a pier or multiple piers with a girder.

Again....glad you are back UB.