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Basement - minimum ceiling height

MrKropp's picture

Is there a minimum ceiling height for a finished basement per the International Code? What is the typical slab to joists height in basements in newly constructed homes?

Excavators just finished digging the hole for the addition on my older home. I went out and measured in reference to a basement window. Depth of excavation appears to be 4" deeper than existing basement, which I presume is the slab depth.

Problem is slab to joists hieght in the existing cellar is only about 7'. I'm afraid instead of getting a basement I'm getting an extra deep crawl space.

Mike K


Amateur Home Remodeler in Aurora, Illinois

Mike K

Amateur Home Remodeler in Aurora, Illinois

(post #67387, reply #1 of 11)

IRC says not less than 7' from finished floor to the lowest projection in the ceiling for habitable rooms. One exception is that beams may project down not more than 6" and be spaced at least 4' O.C. It makes no allowances for duct work projecting down more than that. Minimum height in basements without habitable spaces is 6' 8" with beams and ducts not less than 6' 4".

I would consider adding another course of block to the foundation if possible. That would put the new floor one step down from the existing floor.

Woody

(post #67387, reply #2 of 11)

I was once told that in Gwinnett county a heated are, which defines a living space, must have the majority of said space with 7'6" ceilings. Personally, I never validated this information, but if I were doing by code I'd probably go with local codes vs. International codes.

(post #67387, reply #3 of 11)

Thanks Guys.

What I was assuming was going to happen was that the basement slab for the addition would be below the slab of the existing house. That way the first level floor in the addition is at the same height as the floor in the existing house, but the basement is 8' deep.

I guess tomorrow I will call the local building inspector and find out what my city considers the minimum ceiling height and go from there. I specifically told my GC I wanted a full depth basement so I could finish it. That's not what I got.

Mike K


Amateur Home Remodeler in Aurora, Illinois

Mike K

Amateur Home Remodeler in Aurora, Illinois

(post #67387, reply #4 of 11)

Something to note. The slab foor in the addition to my house is lower than that in the 'main' house, providing more headroom in addition basement. This resulted in the footing for the 'main' house being exposed. I had to have a block poured along the exposed footing of the 'main' house to support that footing.

An ex-boat builder treading water!
An ex-boat builder treading water!

(post #67387, reply #5 of 11)

I finished a basement that had 6'10" ceiling height. I told the homeowner that 8' was required for this. Since the expence wasn't worth worth to excavate or raise the floor. The room was finished with the lower ceiling height. It is now classified as a storage room. As the inspector told me originally, you can store a couch, pool table, TV etc. Everybody is happy.

(post #67387, reply #6 of 11)

Chris,

I'll have to make sure you don't talk to my contractor!

I called my GC today and he agreed that 7' was not acceptable. The excavators will be back to dig deeper.

Mike K


Amateur Home Remodeler in Aurora, Illinois

Mike K

Amateur Home Remodeler in Aurora, Illinois

(post #67387, reply #7 of 11)

-  Ummm...what do the drawings show?  


-  Did someone define "full height basement" to the GC and the excavator?


-  Have you accounted for any pipes, ducts, etc., that may hang below the joists, and how you're going to fur the ceiling below them?


- As mentioned above, have you taken into consideration what you're going to do with the exposed footing at the existing house?


Bob

"Brilliance!! That's all I can say- Sheer, unadulterated brilliance!!" Wile E. Coyote- Super Genius

(post #67387, reply #8 of 11)

Bob,

Excellent questions.

Q: Ummm...what do the drawings show?

A: I designed the addition and submitted the drawings to the GC. He told me he would draw the working drawings and get the permit. Instead of drawing a complete set of working drawings he marked joist locations, electrical outlets, etc on my drawings. He added a few sections showing construction details.

I was taken back by the way he did it. I questioned how he could get the permit on drawings that lacked much detail. He said he had done a number of projects in my town and that he had a good relationship with the building department.

In hindsite I should have demanded a more detailed set of drawings. At this point I think I'm going to have to sit down with the GC and go over the drawings. I think in order to avoid further miscommunication we need to get more detailed drawings.

Q: Did someone define "full height basement" to the GC and the excavator?

A: Yes I verbally told the GC I wanted 8' slab to joist clearance. I think that did not get communicated to the excavator because of the lack of detailed drawings. From my perspective it is the GC's responsibility to communciate to the sub, not mine.

Q: As mentioned above, have you taken into consideration what you're going to do with the exposed footing at the existing house?

A: House is over 100 years old, stone foundation. There does not appear to be a footing. Foundation wall is about 18" wide. They have dug down 4" below the level of the slab in the existing house. If there had been a footing it would have been exposed.

Bob

Mike K


Amateur Home Remodeler in Aurora, Illinois

Mike K

Amateur Home Remodeler in Aurora, Illinois

(post #67387, reply #10 of 11)

I am a DIY and I hope someone with more experience comments. If the excavation has been dug 4" past the base of the 18" foundation wall, what is supporting the foundation wall? The Building Inspector in my town said that the 4" slab was not adequate support.

An ex-boat builder treading water!
An ex-boat builder treading water!

(post #67387, reply #11 of 11)

BowBear,

Apparently 100 years ago there were no footings. Yes, if we put the basement slab of the addition below the basement slab of the existing house we will have to have underpinning.

My issue is I'm paying for a basement that I can finish. At 7' depth that is not what I would get.

Mike

(post #67387, reply #9 of 11)

Waht does the plans call for?

Joe Carola
Joe Carola