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-   -   Confused with code requirements about structural sheathing. (http://www.diychatroom.com/f19/confused-code-requirements-about-structural-sheathing-31917/)

Clutchcargo 11-15-2008 01:07 PM

Confused with code requirements about structural sheathing.
 
First some background, I'm rebuilding a single level sunroom and adding a level. It will now be two levels. The size is 7'4" x 11'. I tore the old sun-room to grout the open cell block foundation and now I'm rebuilding. I've got the first floor framed and I've begun to add the sheathing. Before I get too far with the sheathing, I want to make sure I'm doing it correctly.

The height of the wall from bottom plate to top plate is just short of 100" + the rim joist and sill plate So the total height from foundation to top of top plate is about 110 5/8".
For the 11' wall section there are two windows (RO 34x54"). They are 21" from edge of each wall and 22" between.
So looking down the 11' wall it looks like this:
' 21" Wall
+ 34" RO for window 1
+ 22" Wall
+ 34" RO for window 2
+ 21" Wall
= 132" approx
I've begun to hang the sheathing (15/32" CDX) horizontally and used the first panels to cover the rim joist and sill plate.
I believe the Massachusetts code follows IBC pretty closely and the area I live in is subject to less than 100 MPH winds.
Should I be concerned about the lateral strength of the wall?
In the old wall there were 3 windows and they were about 10" from the corner and there was no lateral support. I guess that was good enough for code requirements 85 years ago.

Marvin Gardens 11-15-2008 02:27 PM

The taller the structure the more you should be concerned with wind. We don't get 100 mph winds here either but last winter I watched as a building blew down. It was a two story and the building next door had recently been torn down. This left the building open to the wind.

Freak winds do happen. The Columbus Day storm here in the NW is a good example. It really did some damage and many homes were totaled. It was estimated that the winds hit 120.

Also windows do not have any lateral support which puts the pressure on the framing next to it to do double duty. The more the windows the more the rest of the structure has to handle.

I am in the process of building a solarium. It will be overbuilt since we do have some gusts of 70 at least once ot twice a year. With all the windows I want to have lots of support adjacent to it.

Just my 2 cents worth and with inflation that isn't worth much.

buletbob 11-15-2008 02:51 PM

here is how i would do it, run your first 8' sheet out nailing it 6" oc along the sill plate and 6" oc up along the 4' edge and 8" oc on each stud (code is 12") then install your half sheet on top nailing with the same spacing, since the wall has to be blocked out anyway install your blocking along the 8' seem in the plywood. use 8d full round head nails. that should be well suited for your none wind zone location. but check with your local building dept. BOB

Clutchcargo 11-15-2008 03:10 PM

Thanks Bob, that would leave me with 2 sets of block in the joist bays because the total wall height is 110+" from the bottom of the sill plate to the top of the top plate.
I'm hopefully wondering that this structure is small enough that 21" & 22" and 21" continuous areas are enough for the wind load.

Marvin Gardens 11-15-2008 03:18 PM

Perpendicular blocks will not provide much, if any, lateral support. Try angle braces. This will give much more lateral support.

buletbob 11-15-2008 03:35 PM

Quote:

Originally Posted by Marvin Gardens (Post 185382)
Perpendicular blocks will not provide much, if any, lateral support. Try angle braces. This will give much more lateral support.

Your absolutely correct, But I believe depending on his code he is still required to run the blocks between the studs. so why not bring them down to meet the seem? here the blocks are required. and 1x4 Let in bracing would be the choice I would use here near the water.but would be a over kill for a none wind zone location, just my opinion, BOB

Marvin Gardens 11-15-2008 03:49 PM

Quote:

Originally Posted by buletbob (Post 185390)
Your absolutely correct, But I believe depending on his code he is still required to run the blocks between the studs. so why not bring them down to meet the seem? here the blocks are required. and 1x4 Let in bracing would be the choice I would use here near the water.but would be a over kill for a none wind zone location, just my opinion, BOB

Would angle bracing be acceptable for blocks or is it required to have actual fire blocks? I know that code can be a real stickler sometimes and there is no altering it.

Clutchcargo 11-15-2008 03:53 PM

Quote:

Originally Posted by buletbob (Post 185390)
Your absolutely correct, But I believe depending on his code he is still required to run the blocks between the studs. so why not bring them down to meet the seem? here the blocks are required. and 1x4 Let in bracing would be the choice I would use here near the water.but would be a over kill for a none wind zone location, just my opinion, BOB

You're correct and it does at a few more nails for an increase in the total shear strength of the nails. The part I'm having trouble understanding is the shear wall length. Since this is a bump off of the main house does it come under the same requirements as the main house or is it included in the main house's structure so I don't need to put as much thought into the racking effects of wind load. I don't want to waste a day not working on this project and waiting to talk to the building department with the weather being somewhat nice tomorrow because weekends are my only chance for working on home projects.

buletbob 11-15-2008 04:00 PM

I'm Sure they would be accepted for fire blocking, You see them all the time on your old balloon framed homes , the inspectors here like to see them around mid point on an 8' wall and a double row on a 10' wall or taller. Here on the island with all different town ships they with in themselves have there Owen set of codes. BOB

Marvin Gardens 11-15-2008 04:54 PM

Quote:

Originally Posted by buletbob (Post 185404)
I'm Sure they would be accepted for fire blocking, You see them all the time on your old balloon framed homes , the inspectors here like to see them around mid point on an 8' wall and a double row on a 10' wall or taller. Here on the island with all different town ships they with in themselves have there Owen set of codes. BOB

I love multiple jurisdictions. We have that problem in Oregon where the county says one thing and the city says another. Mostly on what you can do with things other than building but it is frustrating.

When I was a timber faller the Forest Circus told us we had to leave wild life trees and if we didn't we would be fined $1500. OSHA said if we left them we would be fined $2500. So we cut em down because the fine was cheaper to pay the Forest Circus. We just included that in the bid.

My vacation home has 23 foot walls and not one fire block. When I remodeled it no one said word one to me about it. I found that odd that they wouldn't tell me to put them in.

When I did my buried electric the county didn't care about how deep I buried it as long as it was in conduit. The state told me I had to be down 2 feet. The electric co-op told me that I had to be down 6 feet.

The county said I could put in water lines right next to the power line, the state didn't care what I did, the electric coop said anything in the same ditch had to be separated by 18 inches.

So many different rules, no wonder I am so confused.

Clutchcargo 11-15-2008 06:17 PM

Marvin, for your solarium, how do you overbuild it for lateral strength?

Marvin Gardens 11-15-2008 07:17 PM

Quote:

Originally Posted by Clutchcargo (Post 185475)
Marvin, for your solarium, how do you overbuild it for lateral strength?

I put in cross bracing at the corners from top to half way down and then put another brace half way down to the other corner. These nailed into a 4x4 on the corner and a 4x6 12 inches in from the corner. The rest of the front is going to be windows.

My ceiling windows are old double glazed commercial sliding patio doors. They are really heavy and I am not sure how I am going to keep the roof stable enough so this thread is interesting to me.

Sometimes I just walk away from a project for a while and think about it. I am in the thinking mode now.

The roof will be shed type and will be 12 feet with 4 feet of shingles and then 8 feet of glass to the edge. I had thought about cross bracing at the first 4 feet but that would do little to keep from having wind damage because of the leverage of the other 8 feet.

Then I thought of angling the sides but then I would have to get some more glass as windows would not work at an angle.

Then I thought of putting in some angle supports and make them look like a "design feature" :yes::yes:. Kind of like stealth support.

I am still thinking...... We do get some serious wind out of the gorge here and wind load is a big concern.

Clutchcargo 11-15-2008 07:34 PM

I Level has a couple of products that only requires 21"; Shear Pnel and Shear Brace. It needs to be directly secured to the foundation. Unfortunately, I'm beyond that on this project. Strongtie also has a product meant for garage openings, it looks really expensive though.

Marvin Gardens 11-15-2008 07:48 PM

How about cable with turnbuckles? I have used those on wind towers. East to put in even if the job is almost done.

Just put in some lag screws at either end and a turnbuckle in the middle. You can tighten them to the point where you can pull the wood out if you want to.

We built a 40 foot tower for a guy so he could shoot sage rats. We used cable and turnbuckels and that thing doesn't move much in 70 mph winds and it isn't all that large at the base. Of course it doesn't have any siding to catch the wind but the deck on top is enclosed to 3 feet and at 40 feet has a lot of leverage.

Clutchcargo 11-15-2008 08:03 PM

I'm going to have to talk to the building inspector to see if he has any suggestions or if it's even an issue. I'm hoping that he'll tell me to just sheath the interior with plywood as well and that will do it.


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