SYP beam size for 10.5 ft span

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  #1  
Old 09-29-05, 10:18 PM
dlibke
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SYP beam size for 10.5 ft span

What I have is a living room that projects 8.5 ft beyond the foundation. The width of the room is 20 ft and 3 steel tubular (4" dia) posts support the over hang and a 12 ft x 20 ft deck.
A 2x4x16 wall supports a 4 x 12 roof. The outside dimension of the living room is 18 ft x 20 ft. The projection and deck produce a two bay car port. On the inside of the wall is a metal fireplace w 6.5' x d 3.5' with a raised hearth and wrapped in a 2x4 wall with thin sandstone pieces around the opening. On each side of the fireplace are 5' Atrium Wood french doors with 2 2' x 5' fixed double pane window above each door.

Now for some history. I bought this house at HUD auction. The metal framed slider and windows on each side of the fireplace were broken out. While removing the sliders and carpeting signifcant water damage to the flooring was discovered on fireplace side jamb. Inspecting the framing for water damage from carport area revealed a single 2x10 header nail to 2x10 joists with only 1/2" of good wood left in the header for a 2' area under the door jambs. I replaced the single header with a double 2x10 header and through bolted the 2x8 deck header 2' OC and staggered vertically to the house header.

A few years later the 10.5 ft span has deflected 3/8" resulting in the french door above not to latch. Since I am now have to rebrace the house and deck along with unbolting the deck and recutting the joists, I want a good idea of the width and composition to augment the 2x10 header.

Any help would be greatly appreciated.

Dave
 
  #2  
Old 09-30-05, 06:10 AM
Join Date: Dec 1999
Location: South Dakota
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SYP Beam

Dave:
I am going to give you my recommadations. You must also bear in mind that I cannot view your problem, so I may be way off base. You will also probably get alot of responses to my answer. All these guys are smart and very good at construction. We may have different opinions, but in the end it all works and nothing falls down. Your house appears to be very strong from what you have stated. Your concern seems to be with the 3/8 sag making your french door not open correctly. I would not take things apart for 3/8" on an inch. You might do more damage. Since the deflection happen some years later, I would guess it is just from normal settleing, other wise it would have happened sooner. What I would probably do, is open up the bottom of the french door and put in some oak shims. In other words, relevel the door, without tearing into the structure. 3/8" on an inch is not much in construction. Most would not even notice it. Your door however made the problem come to light. In my big old house, I have a beam which has setteled over 1 1/2" in 10 years. It is a beam that is sagging in my basement.
People ask when am I going to fix it. I just say, I am going to see how far down it will go. So I guess its up to you, but like I said, you might do more damage then you have now, plus cost alot of money. Good Luck
 
  #3  
Old 09-30-05, 06:18 PM
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Dave,

If I understand correctly you have an 8'-6" cantilever unsupported below with wall and roof loads above. Those are tremendous loads bearing through the door (am I understanding that it is below at the wall that supports the cantilever joists)? I would say that your 10' header span needs at least a 4x12 header. I would use 4x4 king studs and dbl trimmers to support the loads. Hopefully you have a good footing through there.

I hope this helps.

Brian Garrison
General Contractor/Professional Building Designer
 
  #4  
Old 09-30-05, 06:56 PM
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Syp Beam

Brian:
The 8' 6" overhang is supported by 4" dia. steel posts.
 
  #5  
Old 10-01-05, 11:16 AM
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Jack,

my interpretation is that the lally columns support the deck which extends beyond the cantilever. The columns if I understand correctly are out at 12' beyond the cantilever. They would not support the cantilever but would support the deck. The problem is not only is half the deck load bearing on the same wall line below but also the cantiver. I would almost reccomend that an engineer come calc. the loads on the header because they are tremendous. 3/8" sag in a header is extreme. It shows the loads impacting the header. You can do nothing and simply remove the shims that are at the top jamb but dvae is asking for the reccomended header size. Our rule of thumb here is bearing first story wall lines to be 4x12 minimum. Upper floor we reduce to 4x8 minimum for standard windows and doors up to 6' wide.

Dave,
I would ask that if I am misunderstanding what is existing you let you us know so we can help clarify our reccomendations.

thanks

brian garrison
 
  #6  
Old 10-01-05, 11:53 AM
dlibke
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To clarify further the current inadequate beam and load I give the following:

The canterlevered joists attach to 2 ply 2x10 beam constructed of a 2x10x20 and a 2x10x10.5 and 2x10x9.1 with the shorter pieces' ends rest on the middle post (original placement of post) with the a 2x8x19 deck band bolted to it. The problem is that the fireplace surround (17' height) consisting of studs, 1/2" drywall, 4x9 cedar mantel, PA blue stone veneer raised hearth, and 30 sf AZ rose sandstone around the opening places a point load 79" and 95" for each end of the beam. The posts sit on ~4" of concrete overlay of a previous surface above whatever footing that might exist because the concrete is 4" above basement door sill in the carport area.

If I had the weight (lb/sf) of a typical 2x4 exterior wall then I could calculate the roof + wall + floor load on the beam and then add the load of the fireplace across the center 7' of the beam. The center post carries half of the rwf plus 2/3 of the fireplace load.

Does anyone have an idea of the weight of an exterior wall?

Unfortunately I am restricted to 10" beam depth but can make it as wide as necessary and add flitch plates. Also centering the middle post on the beam would reduce the span to 9' 9".

Any help is still appreciated.

Dave
 
  #7  
Old 10-01-05, 12:25 PM
dlibke
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Brian,

The beam has three posts and the deck has its own three posts. The beam carries half the weight of the deck plus my previous post loads

Dave
 
  #8  
Old 10-01-05, 12:32 PM
dlibke
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syp beam

Brian,

The header referred to is the floor joist header not opening headers. It is the joist header, originally a single 2x10x20', which I doubled. It has always been supported by three metal posts albeit with an offset center post.

Hope this helps

Dave
 
  #9  
Old 10-01-05, 01:09 PM
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Syp Beam

Dave:

Your explanation to Brian is exactly as you stated it at the start. I sketched it out from your first post. My hat is off to you. You know your building procedures really well.
 
  #10  
Old 10-01-05, 02:51 PM
dlibke
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Jack,

You are right. After this thought provoking discussion, I believe I will move the center post 9" to product 2 equal spans of 9' 9". Now the questions are: Will a simple 3 ply 2"x10"x20' beam carry the load across to 2 spans of <10' without deflection? Or should it be 3 ply with a single 1/2" plywood flitch plate? Or should I just bite the bullet and make a simple 4 ply beam?

I already have a 4x8 sheet of 1/2 plywood. Work wise, the beam choice only effects the amount cut off of each joist and whether I buy 1 or 2 2x10x20 syp boards. With my neighbor's help, I believe I can get the 2x10 in place in one piece which will be stronger than 2 pieces. I will use hangers to attach each joist to the beam.

I will address the footing issue when I lower the carport concrete to below the basement door sill.

Answers to the above questions would be greatly appreciated.

Dave
 
  #11  
Old 10-01-05, 03:06 PM
Join Date: Dec 1999
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Syp Beam

Dave:
You could use the 3 ply with the 1/2" plate, and it would probably be fine. But I think I would bite the bullet on this one and go with the 4 ply. You have some unknowns here, and even though the 4 ply may be over building a little, it may end up being the wise choice down the road. Just my thoughts.
 
 

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