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Old 01-08-2010, 09:31 AM   #1
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Need remodeling advice! Structure


Hi,

Never posted here before...so thanks in advance for anyone who can give some advice. We inherited a 3 bedroom vacation house in NY state, built around 1960. It measures about 25 x40 the roof pitch is kind of shallow, no more than 30%. We would like to rip out the ceiling in the front third of the house (going length wise)...its an area about 15x25 and vault the ceiling.
I am enclose pics of the room and the attic construction. The rafters are 2x8's 16 on center nail to a 2x12 ridge beam. The builder did construct some
knee walls on third in I guess for extra support when it snows. There is also some funky support structure in the attic ceiling which does not apparently really support anything. We where thinking of sistering in 2 x 12's against the existing ridge bean...beafing up support walls that would transfer the load to the foundation and sistering in 2x10's against the roof rafters, maybe every other on with notches fitting into the outsides wall to keep the walls from spreading. There would also be collar ties about 2 feet from the right for additional reinforcement.

I am enclosing pictures of the outside and inside and the attic so you can see what I have here











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Old 01-08-2010, 10:08 AM   #2
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I can't really tell from the pics what is going on
Or where you want to rip out & open up - I imagine the 15' labelled pic
The problem is we don't know what this looks like above - which attic pic ?
You have multiple 2x's in the attic that looks like a support beam
I'd be very leary of taking any of that apart

You need A Pro to look at this IMO

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Old 01-08-2010, 10:35 AM   #3
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What I think I see is this.
A main support beam running the length of that room about where your 15' line is drawn on the ceiling. It supports the ceiling joists since the span is very long.
Knee walls adding extra support for the roof, presumably for snow load.

You need to consult a structural engineer for advice on how to remove that stucture and resupport the roof. I suspect you will need to sister all the roof rafters with something much larger to support the load. Not sure what you would do to replace the rafters tieing the two walls together and keeping them from bowing out under the load.
Another option would be rmove that section of roof completley and instal engineered scissor trusses.

This is not simple job of removing the joists and drywalling the bottom of the rafters.
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Old 01-08-2010, 11:08 AM   #4
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I have enclosed a photo with captions. From what I have studied...I would definitely transfer part of the roof load onto a new ridge beam formed by
sandwich 2 2x12's on each side of the existing ridge board. This would be supported by the outer wall on one end and interior wall which forms a corner
near the stove which is already supported in the crawls space by a cinder block pier. I would also sister in 2x10's to the existing 2x8 roof rafters. The collar ties would remain, but those knee walls in the attic would be removed as well as the ceiling rafters
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Old 01-08-2010, 11:16 AM   #5
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Joed is right- that is a main support beam
Removing it & the 2 knee walls means structural work & redesigning the whole roof load
With a 25' total span 2x12's would work as rafters
But then you need to worry about pushing the walls out without the ceiling joists
Is there a lumber yard nearby where they can run the numbers ?
Or a structural engineer/architect etc you can hire to redesign the roof load ?
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Old 01-08-2010, 11:59 AM   #6
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A properly sized ridge beam would carry the load of the roof and prevent the walls from blowing out, but I think it would need to be more than a pair of 2x12.

You can look up span tables for this exact application (in engineered beams) in the pdf at ilevel.com

If I'm reading the table right, you'd need a 5x11 LVL (three 1.75x11 attached together. Your posts and foundation will carry half the weight of the roof, including the snow and wind loads, so they need to be sized properly too.

But you'd need to replace the existing ridge board with the LVL, wouldn't you? That would be tricky.

I don't think those "collar ties" are actually doing anything -- but I wouldn't mess with anything myself unless someone who could do the calculations signed off on it.
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Old 01-08-2010, 01:21 PM   #7
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I an now wonder if the ldl's could be placed below the existing ridge board. I forgot to mention that the roof is being opened up anyway
Or...maybe they could be sistered in with the ridge board.
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Old 01-08-2010, 01:35 PM   #8
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I think you need to fasten each rafter to the beam with joist hangers. Don't know for sure. If you put the beam under the existing ridge, you wouldn't be gaining much ceiling height.

I looked into the idea of raising the ceiling in our living room, but there were just too many unasnwered questions and potential pitfalls. If anything ends up not quite right you can ruin the building.
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Old 01-08-2010, 02:22 PM   #9
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Pyper is absoutely correct, if you replace the existing ridge board with a properly sized ridge beam, you need to do several things:

1. Make sure the ridge beam is adequately sized to carry all loads, dead and live, with the appropriate safety factor.
2. Make sure the supports for the ridge beam are properly sized for the vertical load, and are designed to resist buckling.
3. Make sure the vertical load from the ridge beam is carried down to a properly designed foundation by appropriate framing.
4. Make sure the rafters are properly connected to the ridge beam using appropriate hardware such as Simpson connectors.

Typicall the design of a ridge beam system would be done by a structural engineer.

If you put in a ridge beam, you do not need collar ties, which would allow you to install a cathedral ceiling. The collar ties in the existing framing are there to equalize uplift pressure on the roof, they are not there to resist outward thrust against the walls. Outward thrust on the walls is resisted by the ceiling joists. The knee walls provide support to the rafters, allowing the framing to use smaller rafters than would be needed if there were no knee wall. Should you remove the knee walls, you would need to review the rafter sizing, which you check anyway.

By the way, the framing looks pretty good to me, seems like a careful job, in fact there is some redundancy in the framing, which is not a bad thing in this case.
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Old 01-08-2010, 02:27 PM   #10
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Just as an example
For a 24' 6" span & only a room 17' wide they spec'd (3) 16" LVL's as my
ridge beam
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Old 01-08-2010, 03:21 PM   #11
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That quad 2x10 beam looks like it is floating over nothing. It looks as though there was a wall at one time parallel to the front wall (back by the table.) and someone took it down. The structural attic beam looks to be about 2 feet or so in front of the fireplace and running to the back of the house. Is there another wall bisecting this area?
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Old 01-08-2010, 03:27 PM   #12
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Quote:
Originally Posted by Ron6519 View Post
That quad 2x10 beam looks like it is floating over nothing. It looks as though there was a wall at one time parallel to the front wall (back by the table.) and someone took it down. The structural attic beam looks to be about 2 feet or so in front of the fireplace and running to the back of the house. Is there another wall bisecting this area?
Ron
Actually if you look back at the 1st sets of pics it shows the quad beam extending past the stove pipe
That should have it landing on the wall behind the stove
Hopefully there is support under that wall down to the ground or another beam support in the floor
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Old 01-08-2010, 03:41 PM   #13
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Got it. The beam is behind the fireplace, not in front.
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Old 01-08-2010, 04:55 PM   #14
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Quote:
Originally Posted by echelonphoto View Post
I an now wonder if the ldl's could be placed below the existing ridge board. I forgot to mention that the roof is being opened up anyway
Or...maybe they could be sistered in with the ridge board.
You have many options that can work for you. Putting a structural ridge underneath the existing ridge is done alot. I've done it many times. This has to be designed by an Architect or Engineer. No one here can tell you what size beam to use. This is not the place to do this. You can listen to the suggestions you get here and that will help you understand your options when you seek professional help form an Architect or Engineer.
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Old 01-08-2010, 05:20 PM   #15
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Change the size of your picture so they don't make the forum scoll to view the entire post. They should be max 720 wide. 640 is the most comon standard used forum pictures.

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