I cannot find anything specific regarding lateral support for ICF walls.  The IRC doesn't mention the subject.  The Prescriptive Method says that lateral support will be provided by the roof and floors assuming an above wall height of 10' or less.  Has anybody seen this issue referenced in the IRC?  Any feedback please.

Earl

ELEDSALL: Your post is a little confusing. The IRC codes where adopted verbatum out of the prescriptive methods so I believe your wording has thrown us all. Please explain in a more detailed version.

Dave

I'm required by engineers to install blocking 10 - 12' (5-6 joist bays) back in from the parallel walls rim board and also add a CMST strap to it.

Is anyone else required to use PT or LTT's every 4' around the entire perimeter of the floor diaphragm? or I am the lucky one have this siesmic code requirement

Backfill or no backfill this happens on every job

Wow! In my area about 10% of the jobs have blocking, but not to that extent. Inspectors in my area either dont know or dont care.  Typically blocking is 2x10's back 2 joists at 3 or 4' o.c. There are a few areas in Michgan (larger municipalities) where the bldg departments actually hire outside engineers to review all plans before issuing permits. These are the ones that have blocking, etc. I know nothing about seismic, but I'm sure the requirements are more rigorous than non sesmic areas.

Bunt

You mean for open-web wood trusses only Chris, or for TJI as well?

We build in a seismic area, but I will not build combustibly.

For TJI as well.

I believe both Oregon and Washington are the same siesmic as I, but I get the brute end of engineering here.

Want to see some wild rebar spec's? You're head will spin.

Ya, sounds like you're describing SoCal...

Actually NorCal, bay area

I sure hope I'm not going to have any problems, but neither do I expect to. In the design for my house I have no connection at all between the floor and the end walls which are parallel to the joists. The only IRC requirement I read for ICF wall bracing are the requirements for minimum length of solid wall based on wind loads, and for designs in seismic areas. We're not in a seismic area, and we fall into the minimum psf column in the wind pressure table.

The only lateral support requirements I read in the IRC are in cases of backfill of 4' or more for all foundation walls, and for masonry block walls. I didn't look to see what it says for stick walls.

The BI didn't raise any questions when he reviewed my plans for the building permit. I even loaned him a copy of the Prescriptive Method and the Build Block installation manual. But maybe that's because he is only passingly familiar with ICF construction. My civil engineer cousin didn't raise any questions either when he did quick review of my plans, but that review was primarily focused on the footers.

Yes it looks like we're about the same.

Although you've got alot of liquefaction area. Put in alot of pilings?

Here's ours. Liquefaction areas are where old landfills were, or where alluvial deposits were left by rivers. (soft soil)

Well, the first thing to do Mac is to have your screen cleaned.

Mac; I have a theory with engineering

Until something happens everyone is lax, once there is a problem that gets attention the rules and spec's tighten up

I remember living in Ontario, decks were a joke, literally, people slammed them up on weekends/evenings...no permits, no inspections and no one ever said anything, suddenly on a quiet Sunday afternoon in August around 1994 a deck collapsed on the back of a new home, old lady and a kid were on the deck (oh, and the BBQ as well), within 30 days every deck regulation was fully enforced in that area and within a year it was enforced across the Province. Deck regs. their seem more strict than the floor of the house now.

California here has always been tough since it is known as the earthquake place, I wasn't here but everyone tells me after the '89 quake that destroyed so much in the Bay area including the collapse of a portion of the 880 freeway, codes were tightened like crazy, so I bitch about it a little here and a little there, but in reality, not if but when another major 7.0+ hits we should be safe becuase of the precautions. Most areas should adopt this practice but don't, they haven't had the problems of earthquakes or decks falling off.

Chris:
I was in Barrie installing decks on custom homes back in 95, I remember my bosses watching me put the ledgers on "properly" and nitpicking everything structural....Once the stuctural work was finished, they were out snowmobiling....

Mac, you have to mechanically attach every 6' to the concrete on the non-load bearing side or the walls will be considered to be the height of the 2 floors combined which would require engineering on a standard home.

Dave

ok, ok, my screen is clean

I'm either blind or dense because I sure can't find that requirement in the 2006 IRC. Can you point me to it? I find what reads like that requirement for townhouses in seismic cat C and all buildings in seismic D and above. I'm in seismic B.

I was wondering if anyone else could see that, or if it was just my LSD flashbacks from from the '70's...

Mac, I don't have a IRC at home but a quick look at Prescriptive may prove you to be right with the seismic zones. Any ways we attach the non bearing side every 6' with an anchor bolt. Maybe its just cheap insurance after all. Thanks for pointing that out.

Dave

And if that one doesn't do it, try http://setitfree.net

... squeeky clean