Diagnal Framing Structure Question

Statjunk · Jul 3, 2007

Hey guys,

I'm remodeling a house and one of the projects that I'm about to get into is putting new windows across the front of the house. The issue is that there are diagnal framing structures that cross multiple studs. My very experienced buddy tells me that they are there to protect the structure from high wind.

The number of windows that I'll be putting in across the front of the house will not allow me to have this board. Are there other methods to replace this protection in a different way?

The board appears to be a 1x6 running at a 45 across the studs. My buddy told me the name of them but I can't recall what he called them.

Thanks

Tom

Jimbo · Jul 3, 2007

The general term is shear bracing.

Around here, if you mess with walls, you have to have a licensed architect or structural engineer redesign the shear.

My daughter just had a 500 sq ft addition put on her house. They had to completely sheath two existing walls with plywood ( very strict inspection on the nailing pattern on those) to beef up the shear for the load caused by the new roof area, and the one wall ooped up. Engineers plans had to be signed off by the city, and it took 2 go-rounds before they got it accepted.

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Statjunk · Jul 3, 2007

Any body aware of a way to add that strength back without adding the diagonal braces? Could I use a bunch of 2x4's between the wall studs to provide the shear stength?

Thanks

Tom

Markts30 · Jul 3, 2007

Like the man said, you will have to consult an engineer for designing the sheer wall...
I have seen some require sheeting the inside and outside with plywood...
I have seen others require steel studding (heavy gauge) and welded gussets for the sheer strength....
This is not something you can ask over the net...

Frenchie · Jul 3, 2007

...yes, and no... we're talking about a single brace, here?

If you sheath the entire wall with 1/2 ply, you would be dramatically increasing the wall's shear value, don't need an engineer to know that.

Might be massive overkill, though.

This really is a job where it's worth spending a few hundred bucks on an engineer - odds are, you'll save that much, by only doing what you need to.

And your jurisdiction will probably nail you to the wall, if you don't file the right permits.

Geniescience · Jul 3, 2007

Load paths are important to plan, so that every load is fully supported. Under high winds, loads go diagonal, and can be reversed too (gravity might no longer hold the roof down).

See http://www.fema.gov/rebuild/mat/mat_fema499.shtm fact sheets (Load Paths and others), also at http://www.nahb.org/generic.aspx?genericContentID=46305.
Also http://www.coastalcontractor.net/cgi-bin/article.pl?id=18 explains more risks.

david

Statjunk · Jul 5, 2007

The exterior of the house is brick so I can't screw sheets of ply to it. Could I screw in the sheets of ply into the interior? Can you dry wall over plywood?

For the record, this is the only exterior wall that will get fooled with on this remodel. This is also the only sheer brace that will be affected. I can actually keep most of it intact but it will no longer span between the toe and the top plate.

Thanks

Tom

Statjunk · Jul 5, 2007

Geniescience,

Looking at the links that you've supplied it appears that a lot of it speaks to roofing under high wind. If I'm not mistaken the diagonal "wall" 1x6 that I'm speaking of is to stop the house from leaning in high wind. Am I missing something?

Tom

Geniescience · Jul 5, 2007

statjunk said:
.... Am I missing something?

yes. but i am not the right person to describe to you why you need pro help... i wouldn't know how to say it just right in this field, which is not a field I feel comfortable in.

Three people posted before I did, saying you need PRO help. No one posted to say the opposite. No one posted to say, "maybe, just maybe..."

That much is clear to me.

Be well, be nice, have a good day.
david

Frenchie · Jul 5, 2007

Yes, the 1x6 is to stop the house from leaning in the wind; or more precisely, to stop it from falling over in the wind.

You may have to remove enough brick to sheath the wall.

You may simply have to put in some new diagonals. These would have to be in certain very precise locations, with a certain nailing pattern, a certain size nails, etc.

Get an engineer, they'll specify all that for you.

Leejosepho · Jul 5, 2007

statjunk said:
... this is the only exterior wall that will get fooled with on this remodel. This is also the only sheer brace that will be affected. I can actually keep most of it intact but it will no longer span between the toe and the top plate.

Can you possibly post a picture?

Spaceman Spiff · Jul 6, 2007

Hire an engineer and for a couple hundred dollars they'll tell you exactly what to do. Also, if it ever comes down for any reason insurance will pay for it (either yours or the engineer's). If no engineer then you will likely have to pay for it unless you have a really good lawyer.
I'm an architect and I hire an engineer on everything I do. I'd rather they be liable and not me. My liability insurance is high enough as it is!! Don't need that headache!

Statjunk · Jul 16, 2007

Had an older friend of mine that was at one point or another licensed in every trade come over and give me his one-two. He had me rip off the exterior sheathing and replace it with 3/4" ply with screws every two inches.

He claims that the strength of the sheer is determined by how many studs you cross between the bottom and top plate with the 1x6. So I had to cross as many studs as possible because I no longer had enough room between any of my windows to get the sheer strength back.

Cost me a big mac, a double quarter pounder and a beer.

Thanks for all the advise guys. The advise here helped me to trust what my buddy had to say.

Tom

Jimbo · Jul 16, 2007

He summed up the shear issue in about one sentence, and it sounds like you got a good fix on it.

Frenchie · Jul 16, 2007

Wait a minute - didn't you say, earlier, that you couldn't sheathe the wall because it's covered in brick?

Leejosepho · Jul 17, 2007

statjunk said:
Could I screw in the sheets of ply into the interior? Can you dry wall over plywood?

After first being able to actually see the open wall, that is what I likely would have suggested ... and yes, I have occasionally finished plywood with drywall mud right alongside regular sheetrock.

Diagnal Framing Structure Question

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