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Old 12-16-2009, 03:55 PM   #1
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Structural reinforcement needed (ridge beam)


We need some ideas with a structural reinforcement problem: The ridge beam is sagging, and the second floor walls are bowing out.

I bought the house two years ago which looked to be in excellent condition at the time, but soon after the drywall began cracking along the lengths of the collar-ties.
As a background, the basement/first floor was built in 1954 with the second floor added in 1990. The paperwork left by the previous owner shows that the city inspectors signed off on the blueprints, but a final inspection was probably not done.

I modeled the framework in Sketchup7 to find out where things did not match up.
-Basement: Has one continous centerline load-bearing wall, but there are no other interior walls to support the first floor load(walls, appliances, etc).
The north side of the stairs is centered on this line.
-1st floor: The same centerline load-bearing wall exists only along the western two-thirds. In the eastern third, the interior walls land of either side of it.
-2nd floor: There is almost nothing load-bearing! The only thing keeping the roof from collapsing appears to be the bathroom and end walls.
Exterior measurements are about 30' x 30', but the ridge beam is 2'x12', and the collar ties are 2'x6's according to the blueprints.

Our plan(so far) is to add a support beam under the ridge with a post reinforced down to the basement, and to lower the collar ties to 1/3rd up the rafters.
Does this sound like the best/cheapest solution?
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Structural reinforcement needed (ridge beam)-fromnorth-existing.jpg   Structural reinforcement needed (ridge beam)-fromnorth-fix.jpg   Structural reinforcement needed (ridge beam)-fromsouth.jpg   Structural reinforcement needed (ridge beam)-fromeast.jpg   Structural reinforcement needed (ridge beam)-fromwest.jpg  


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Old 12-16-2009, 04:43 PM   #2
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Structural reinforcement needed (ridge beam)


How big is that cantilever?

I think you need an engineer.

Nice sketchup work, btw!

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Old 12-16-2009, 06:08 PM   #3
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Structural reinforcement needed (ridge beam)


If you have serious roof problems, I would agree with pyper that an on site visit from an S/E is required. Our Regs state that collar ties must be in the bottom third, unless the rafters are held together with the ceiling joists. If they are too high the roof can spread pushing the walls out.
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Old 12-16-2009, 06:57 PM   #4
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Structural reinforcement needed (ridge beam)


From your description you have a ridge board, not a ridge beam. A ridge beam is a structural element that is typically supported on both ends by a bearing wall or post system, may be supported in the middle, and is designed as a structural element to support the roof rafters. What you show is a ridge board, which is simply a nailing surface designed to allow nailing surface for the rafters. A 2"x12" board cannot span 30 feet. Based on the drawings, it is not surprising that the ridge board is sagging, and the walls are bowing out, due to vertical load from the roof.

That said, you definitely need a professional structural engineer to make a site visit and provide professional assistance in evaluating options. It would be impossible for someone on an internet forum who has not seen the house in person to make a valid judgement as to the best method of resolving what sounds like a serious structural problem.
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Old 12-16-2009, 08:27 PM   #5
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Structural reinforcement needed (ridge beam)


Thanks, I am just looking for opinions on how to do this, the more information and ideas the better. The cantilever in front is about 3 feet.

I have already spoken with one well S.E., but he only works with large projects mainly. He handed me off to an architect associate to do the drawings/etc., but at this time I simply don't have the extra thousands to run this through the city(and probably pay extra taxes due to the "higher value").
This is a repair to undo incomplete workmanship, not an addition.

After learning about the structural process since buying this house, I'm simply amazed this addition was allowed to be passed.
There is a bunch of paperwork back and forth on allowing a varience for an extra 6 inch overhang, but there may be no final inspection. City Hall had no paperwork.

Last edited by Stillwerkin; 12-16-2009 at 08:31 PM.
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Old 12-16-2009, 08:55 PM   #6
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Structural reinforcement needed (ridge beam)


Quote:
Originally Posted by Stillwerkin View Post
The cantilever in front is about 3 feet.
Yikes! I'm pretty sure 12" is the most you can do with lumber.

Quote:
This is a repair to undo incomplete workmanship, not an addition.

Based on your description and your drawing, I believe you have an incomplete design. You don't have collar ties, and I bet you don't have adequate support for your cantilever. Not unless you have a lot of steel in the floor.

If you go to a real builder supply company, they will have a guy with a computer program who can size an engineered beam. In my house we used a 3.5" by 14" (actual dimension) beam to support a 22 foot ceiling span. I think you'll need a monster to hold up a roof -- plan on a crane.

Someone in a recent thread found a structural engineer to come to his basement, size things up, and specify a solution for $200. Find an engineer who needs the work -- in this economy it shouldn't be hard

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