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Old 08-01-2011, 05:18 PM   #1
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Uplift protection


Attached is a picture of a framing detail. This is a raised rafter plate, mainly to allow enough space for insulation required in the north east.

I intend to use a hurricane tie for the top plates to the ceiling joist. The wall sheathing is in place and nailed to the top plates (picture is BEFORE I sheathed the wall).


The rafter as you can see is nailed to ceiling joist it rests beside, and the facia board will be nailed to BOTH.

Is this nailed connection in combination with the facia board sufficient to prevent uplift of the rafter, or should a second metal strap be used to tie the rafter and ceiling joist together?

This is a 4 pitch roof, and it's blended into the existing ranch.

Thanks!

-- Joe
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Old 08-01-2011, 06:14 PM   #2
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Quote:
Originally Posted by anesthes View Post
Attached is a picture of a framing detail. This is a raised rafter plate, mainly to allow enough space for insulation required in the north east.

I intend to use a hurricane tie for the top plates to the ceiling joist. The wall sheathing is in place and nailed to the top plates (picture is BEFORE I sheathed the wall).


The rafter as you can see is nailed to ceiling joist it rests beside, and the facia board will be nailed to BOTH.

Is this nailed connection in combination with the facia board sufficient to prevent uplift of the rafter, or should a second metal strap be used to tie the rafter and ceiling joist together?

This is a 4 pitch roof, and it's blended into the existing ranch.

Thanks!

-- Joe
What do the plans say? They have to have a detail for that to follow code.

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Old 08-01-2011, 08:15 PM   #3
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Originally Posted by Joe Carola View Post
What do the plans say? They have to have a detail for that to follow code.
I drew the plans. I didn't include any ties in the plan, but the building inspector asked me to tie it for uplift when I got the permit.

802.11 of the IRC (2009) doesn't really give much to design details, i.e, if facia board and ringshank nails are adequate.

Simple framing plan attached.


Keep in mind - I'm not a builder.. When I built my garage, and my horse barn I was never asked to tie the rafters. This is a 40 foot addition to my house, and I understand the standards are higher than an outbuilding.

My feeling is that the nailing in the facia board (rafters and joists are side by side) and the cross nailing between the joists and rafters are enough, but I'd welcome other opinions. Either way it assumes the ceiling joists are tied with hurricane ties to the top plates.



Thanks!

-- Joe
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Last edited by anesthes; 08-01-2011 at 08:21 PM.
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Old 08-01-2011, 09:27 PM   #4
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Assuming your ceiling joists are adequately connected to the walls, the issue is the connection between the rafters and the ceiling joists. I cannot tell from either your plans or the photos exactly how that connection is made, it looks like there are two nails holding the rafter in. If you explain exactly how many nails, and what size nails, are holding the rafter to the joist, that would help. Also, where are you located, and what wind exposure are you designing for?
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Old 08-01-2011, 10:37 PM   #5
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Originally Posted by Daniel Holzman View Post
Assuming your ceiling joists are adequately connected to the walls, the issue is the connection between the rafters and the ceiling joists. I cannot tell from either your plans or the photos exactly how that connection is made, it looks like there are two nails holding the rafter in. If you explain exactly how many nails, and what size nails, are holding the rafter to the joist, that would help. Also, where are you located, and what wind exposure are you designing for?
Hi,

I'm in New Hampshire.

The rafters are nailed to the ceiling joists with two 12d nails.

They are also nailed to the plate with two nails but I guess that doesn't matter for this topic.

For my area (zip 03079), the wind speed design criteria is < 90mph, so I'll use the 90mph column.

In the worst case scenario, I think it requires 489lbs/connection ?

What do they mean by "Span" in 802.11 ?

-- Joe
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Old 08-02-2011, 08:29 PM   #6
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Well, I made a decision.

For the top plates to ceiling joist I used two H2.5A ties per joist connection, which are fastened with 10 8-d nails each.

For the rafter to ceiling joist, I used a LSTA-24 at a 30 degree angle, and 8 nails each.

The H2.5A is rated at 600 lbs uplift, and the LSTA-24 has a load capacity of 1,234 lbs.. This is way more than the requirements and in addition to a fully nailed facia board, it's not going anywhere...

So with this configuration, I have the min 10 1/4" over the plate for R38 insulation and room for a baffle.

NH state energy codes are tough! If you can't fit R38 over the plate, you must use R49 in the ceiling!!!

-- Joe
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Old 08-02-2011, 08:57 PM   #7
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Got to say, that’s the first time I’ve ever seen a roof framing detail like that before.
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Old 08-02-2011, 09:03 PM   #8
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Originally Posted by kwikfishron View Post
Got to say, that’s the first time I’ve ever seen a roof framing detail like that before.
It is method "D", which from talking to builders is becoming fairly popular.

Unfortunately, I built my walls on the ground, and used wall jacks to stand them up (40 feet long) fully sheathed so I couldn't use the tie method in figure D. Which put me in a minor panic. Only one spot was left unsheathed over a window, which I covered a day or two later. Ripping 80 feet of sheathing off wasn't an option.

If you look closely at figure D, they used a really nice hurricane tie (on the JOIST) that nails behind the sheathing, and the rafter to joist connection is 6 nails. However, the footnote indicates that additional tie may be required for uplift, which my building inspector also pointed out.


The ONLY thing a raise heal/rafter plate gets you is room for insulation over the wall. As more and more states adopt the intense federal energy codes, you will see more and more homes framed this way or similar.

-- Joe
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Last edited by anesthes; 08-02-2011 at 09:05 PM.
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Old 08-02-2011, 09:08 PM   #9
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I find it interesting that you appear to have broken (joined) the top plate on a header cripple, and even seemed to miss the cripple with the joint.
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Old 08-02-2011, 09:19 PM   #10
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I find it interesting that you appear to have broken (joined) the top plate on a header cripple, and even seemed to miss the cripple with the joint.
Those cripples are not nailed in, just kind of sitting there. In fact, I still have not finished the headers. When I did the cutout I started from the floor measurement of where the wife indicated she wanted the window sill, and as I laid it out I realized how silly the 2" cripple studs are. I'm probably just going to use a bigger header all the way to the top plate, and toe nail it. through the sheathing.

Nothing in section 6 says a plate joint can't be over a cripple... ?

-- Joe
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Old 08-02-2011, 10:11 PM   #11
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Going to be difficult to get the required full-height blocking between the ceiling joists with the plate bearing on them...... Everything should line up vertically for transferring the loads to the walls, also. The amount of nails at joist/rafter connection depend on the building span: last two charts at bottom of page here: http://publicecodes.citation.com/ico...002_par023.htm

The Inspector may look for correct amount of end nails in the built-up header also. Raise the headers you have and just add a flat 2x6 under it to nail drywall and curtain backing to without compromising the foam inside face of the header.

Gary
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Old 08-02-2011, 10:50 PM   #12
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Originally Posted by GBR in WA View Post
Going to be difficult to get the required full-height blocking between the ceiling joists with the plate bearing on them......
I never intended on blocking the joists.

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Originally Posted by GBR in WA View Post
The amount of nails at joist/rafter connection depend on the building span:
Which is 16 feet. Looks like 5, 3 on one side 2 on the other is correct.

That seems like a lot of nails for a small area of wood...

I've seen posts from Joe Carola on other forums where he states on a 2x8 rafter he puts two into the seat, and 3 at the rafter/joist connection which is essentially what I did on this, how I built my barn, garage, etc.

I guess I'll ask the building department in the next couple days. Can always alter it if I need to.

-- Joe

Last edited by anesthes; 08-02-2011 at 10:53 PM.
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Old 08-05-2011, 10:45 PM   #13
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Blocking or rim joist is required at the ends to keep the joists from rotating and give the rafters support (a continuous load path to the walls/ground. Here is a better diagram: http://docs.google.com/viewer?a=v&q=...WvZygC-vGi-JoA

Joe frames from the plans which have been approved by the local AHJ. The tables are used by Building Officals, check locally and let us know the requirements.......

Gary
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Old 08-06-2011, 09:45 AM   #14
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Originally Posted by GBR in WA View Post
Blocking or rim joist is required at the ends to keep the joists from rotating and give the rafters support (a continuous load path to the walls/ground. Here is a better diagram: http://docs.google.com/viewer?a=v&q=...WvZygC-vGi-JoA

Joe frames from the plans which have been approved by the local AHJ. The tables are used by Building Officals, check locally and let us know the requirements.......

Gary
I spoke to the building inspector twice this week and he's been too busy to come by. Normally, he doesn't perform the framing inspection until all the partition walls are up, etc.

I believe talking to a local architect I've satisfied the uplift requirement, and I appreciate the comments from forum members.

Regarding blocking, I would think the facia board would prevent such twisting, since it's essentially a rim/band joist however it wouldn't be over the wall.. but I'll be sure to ask the building inspector. Worst case scenario, I can cut some boards to go between as a solid block/bridge however they would have to be on the outside of the wall to satisfy the insulation requirement of being over the wall in full height.

The link you provided is actually the guide I had based my design on, that you had provided me a number of months ago.

In example B of the "raised rafter plate", they have a band joist and example D, which is the style I went with I do see they have solid blocking between ceiling joists. I think if you look closely at picture D, the blocking is actually outside the wall and not over the wall cavity ?


Thanks!

-- Joe

Last edited by anesthes; 08-06-2011 at 09:53 AM.
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Old 08-06-2011, 09:18 PM   #15
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"I think if you look closely at picture D, the blocking is actually outside the wall and not over the wall cavity ?" ------ Read the printed words next to the picture with the lines pointing to "solid blocking", they are in-line, (dotted lines)- under the trist strapping. The Inspector may quote you this: http://publicecodes.citation.com/ico...002_par028.htm

So adding the two framing members- rafter/joists, the least for a 5-1 would be 2x4 rafters w. 2x6 joists, or VS. Adding up to 2x10, thickness/width.

Gary

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