or at least I think it was odd as I can honestly say I'd never heard it before. I was reviewing some house plans with him, and the home is basically a large box. The homeowners are out in BFE, heat with wood and have a very basic design built around a massive hearth. I think it's a good design but he said the fact that they have 2 walls that are rather long (75') without any breaks in the wall makes it "weaker". He wanted to bump out a bathroom to make it "stronger". My gut told me he wanted to add more corners to add more profit, but he said the wall has no wind break. I kinda passed over it and said I would mention it to the owners, but it didn't sit well with me. I kept thinking he MAY be right, but geesh, if the wind is so strong that a 6" concrete and rebar wall is going to get moved AT ALL, then I think an F4+ tornado is at this guys front door and a bump out will make ZERO difference. Plus the interior walls bracing it against the other concrete walls are a factor too. Anybody have any opinions or better yet facts on this? Is this at all a valid concern? Thank you in advance for your replies and have a good day.

Corners would make it stronger, but without corners in a long wall and reinforced correctly it will be very strong. The 2006 IRC addresses minimum solid wall amounts, for when there is to much openings such as doors and windows. The floor system(s), roof and interior walls do add strength.

Thats what I was thinking so thank you for the reply. There is a french door in this wall to the outside deck and about 4 windows, but it's by in large (read 75%+) icf wall. If this wall was 300' I can see his point, but maybe you can elighten me as to why his concern for a wall under 100'? Do you know what section it is in? I looked under exterior walls but couldn't locate it, did I just miss it or is it in another section? Thanks.

oh and this isn't in a seismic zone.

If I am understanding this correctly, why not add a reinforced concrete shear wall inside the house instead of adding a corner and changing the roof line.  Wouldn't that be simpler if more strength is needed in the long wall.

Is this house subject to the IRC2006, or 2009? If so, the building official very well may require you to have the plans stamped by an engineer. The reason being, the IRC specifically limits its provisions to houses that are no longer than 60' in any plan dimension, nor more than 32' floor clear span and not more than 40' roof clear span. I have the 2006 IRC but I can't see that that limitation would have been relaxed in 2009.

R611.2 Applicability limits. The provisions of this section
shall apply to the construction of insulating concrete form
walls for buildings not greater than 60 feet (18 288 mm) in plan
dimensions, and floors not greater than 32 feet (9754 mm) or
roofs not greater than 40 feet (12 192 mm) in clear span. Buildings
shall not exceed two stories in height above-grade. ICF
walls shall comply with the requirements in Table R611.2.
Walls constructed in accordance with the provisions of this section
shall be limited to buildings subjected to a maximum
design wind speed of 150 miles per hour (67 m/s), and Seismic
Design Categories A, B, C, D0, D1 and D2. The provisions of
this section shall not apply to the construction of ICF walls for
buildings or portions of buildings considered irregular as
defined in Section R301.2.2.2.2.

Alton's suggestion of an interior sheer wall is best way to go. But it doen't even have to be concrete. Any interior partition wall that intersects this long wall can serve the purpose with the use of let in bracing that will provide support without changing the dimensions of the walls or their locations. I have no clue as to how this will fit the 'codes' but it was common practice in frame construction 100+ years ago, and those houses lasted long enough for me to see this technique in use, and I'm not that old.

Wes;

you are correct, can be a wood wall, steel framed wall or SIPs wall.

Wes & Chris,

Rykertest mentioned that the long wall was concrete and rebar and it made me think that the wall was below grade.  After re-reading the post now I assume the walls are above grade.  If so, then almost any kind of interior wall properly braced can serve as a shear wall.

I have noticed in some parts of Florida near coastal areas builders use a 2x4 stick-built wall covered with OSB on both sides for shear walls.

Alton and most others are correct. And this is one of the main reasons for the dimensional restrictions on prescriptive homes. Assuming it's built to code, that means an engineer or (qualified) architect is required. An interior shear wall or walls, properly designed, will work fine, though it's easier w/ exterior, especially concrete homes. And they need to be secured to the exterior wall, and especially the foundation.
But just because it is built out of concrete doesn't make it able to resist the lateral wind load by defauld. It needs to be designed for it.

Thanks for all the replies guys. There are a few walls that cross over between the opposing exterior walls that will act as the bracing walls. I wasn't clear as it is an above grade wall but it is over a pit basement. The more I think about it, having the wall that is in th emiddle of the home become ICF with T forms on each end can resolve this problem and benefit the roof system as well. I'm planning on using this new interior icf wall to seperate/privatize the master bedroom, and this will become a concrete capped storm room. Also, I will use it as a middle anchor point for the roof system as well so this is turning out to help the house as opposed to create problems. The owners are liking the change in direction and we'll see what the engineer has to say but so far he seems to like the ideas and the cost won't be that much more.

Good feedback guys thank you again for all your help.