Moving Support Posts (3 Forum threads merged)

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  #1  
Old 09-21-05, 05:28 PM
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Cool Moving Support Posts (3 Forum threads merged)

This is a long post, but I'm trying to include as much relevant info as possible for your evaluation. I've posted this in a couple different forums so forgive me if you've already read or commented on the project - and thanks to Doug for helping me clarify what I'm trying to convey here.

My questions regard a lanai (a covered outdoor room surrounded by the walls of the house on 3 sides and screened on the other side for you non-Floridians). My problem centers on the 27' screened wall.

The lanai is part of an addition done 10-15 years ago. I pulled off the soffit vent and can see that the roof is made up of 2x6 joists, one end of which rests on the original poured cement wall of the house and the other end of which rests on a top plate (2 flat 2x4s) above a double 2x10 header. The lanai itself is 12' deep by 27' long and everything rests on a poured cement slab.

The screen wall header is made in three sections - two 10' sections and one 7' section. Each header section has a king stud at each end that extends all the way up from the sill plate to the top plate, a jack stud that supports each end of the 2x10s and three 2x4s sandwiched together serving as a post in the middle of each header. It's almost as if they framed up three header walls and joined them together. Making sense so far?

I am sprucing up the lanai and want to "adjust" these supports to create larger, evenly spaced openings. There are currently 5 posts along the 27' span including the "king/jack combo" posts and the center supports which create six 5'-3.5' openings

My plan is to insert two 4x4 posts which would leave three 9' openings along the 27' span. I would insert the new posts up to the bottom of the 2x10s, then knock out the old posts, using a reciprocating saw to cut the tops of the king studs flush with the bottom of the header.

Doing this would place the two new posts approximately 1' and 2' away from the respective king/jack stud supports at the joint between each header section. I also considered fastening a metal plate over the joint between each header section to "tie them together". (I should mention that I can't access the surface of the outer 2x10, so this metal plate would be attached only to the inside 2x10. I thought to then use bolts with a countersunk head to tie the inside and outside 2x10s together near the joints) Still with me?

I'm in central Florida, so obviously no snow loads to contend with. Does this plan sound doable? Would three nine foot openings along a 27' span be an invitation to a sagging header? Would anyone recommend a different way of supporting the joints between the header sections? Does it sound like a roof collapse is in my immediate future?

Any input or suggestions from some of you pros out there would be greatly appreciated.
 

Last edited by Star; 09-23-05 at 12:13 PM.
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Old 09-21-05, 07:10 PM
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Cool Moving Support Posts

Merging resulted in my repeating myself - nothing new here
 

Last edited by Star; 09-23-05 at 12:10 PM.
  #3  
Old 09-21-05, 09:12 PM
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Get Professional Help

It sounds to me like the two posts that extend to the top plate, along with their cripple studs, are actually holding up the 2x10 beams. To remove these you will have to replace the 2x10 beams. The other posts may or may not be designed as load bearing, but I would not risk moving them.

BOTTOM LINE: Hire a structural engineer or EXPERIENCED contractor to take a look, it will probably require more work than you are thinking about doing yourself.

Good Luck!!
 
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Old 09-21-05, 09:36 PM
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Star,

9 feet apart in your area seems fine using 4x4's with metal anchors into concrete and metal plates at top.

Hope this helps!
 
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Old 09-22-05, 08:33 PM
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Doug - It does indeed help.

I do have a little further information. Tonight I pulled off the beadboard covering the header. I can see they used 3 different sections of doubled 2x12 and that the posts that don't extend all the way up to the top plate are centered under each section of 2x12. There are two 10' sections and one 7' section (which explains the reason some of the posts aren't equal distance apart).

Now I'm concerned that perhaps the 2x4s at the end of each 2x12 and centered in the middle under each 2x12 section are indeed holding up each section of the header. ACK!

Any thoughts on this? Is there something I could do along the bottom of the header to kind of tie the 3 sections together - maybe insert another piece of lumber that overlaps the joints? Or perhaps join the faces of the 2x12s with a metal plate to tie them together at the joints?

Ideas?
 
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Old 09-22-05, 08:41 PM
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Star,

I need more clarity on this. It sounds as though the 2x12's have been offset during the making of the plies, per say. You are tellling me we need to possibly install metal plates (bolted all the way through existing beam) to overlap the locations where the posts were so that we maintain stability once relocated? Right?
 
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Old 09-22-05, 09:31 PM
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Listen to KPM.

An EXPERIENCED contractor who has put up several dozen or maybe hundreds of these rooms can help you. If you can't find that contractor, then go for the engineer.
 
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Old 09-22-05, 11:01 PM
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Cool Moving Header Supports

Merging resulted in my again repeating myself - nothing new here either.
 

Last edited by Star; 09-23-05 at 12:11 PM.
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Old 09-23-05, 05:55 AM
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Star,

After our discussion, the existing areas of this screen porch are in fact walls. The 2x10's are headers, not beams with 2 - 2x4 top plates on top.

Based on this and the fact that you cannot add additional 2x10 to both outside and inside due to a soffit, the alternatives to removing the 3 vertical 2x4's would be to;

1. Add an additional 2x10 (2) to the interior and use carriage bolts spaced 6 inches vertically and 2'-0" apart. You must ensure that your 2x10's at the joints are resting on the new 4x4 posts with metal post anchors below and post cleats above. Then wrap with 1x stock for a clean look. This would be easiest since you mentioned we hae an existing soffit to contend with.

2. Make a temp wall to support existing ceiling joists/rafters and remove existing exterior wall. Then install a new beam made of 2 x 10 (2) minimum or 2 x 12 with 1/2 ply between so that the load at joints will be resting on the new 4x4 posts with metal post anchors, at 9'-0" O.C. Then wrap with 1x stock for a clean look. This however means the existing soffit would also have to be replaced.

Hope this helps!
 
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Old 09-23-05, 09:26 AM
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Doug - thanks so much for all your guidance and direction on this. I really appreciate your taking the time to help. I'll let you know how it progresses.
 
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Old 09-23-05, 10:54 AM
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I'm not a pro, but I see two problems with your plan, although I believe a double 2x10 should be sufficient for a 9' span. First is the joining of the header sections. With your plan you effectively have eliminated any support under your middle 7" header. I would think you would either have to have staggered joints (meaning a new header), or else the metal plates would have to be very strong and on both sides and bolted, not just lag screwed on one side. An engineer would be able to design something. I would probably spring for a new header, probably a microlam. Also, while the jack studs (or replacement pillars) are providing support, the king studs are also preventing the header from tilting out of vertical. If you cut off the king studs, what will prevent the header from tilting? (in other words, the 10'" sides not being vertical )
I would think a whole new header would be in order.
But again - I'm no pro.
 
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Old 09-23-05, 11:17 AM
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Reworking the Header

Thanks to everyone for your responses. All of this has me thinking maybe my biggest problem is the header, rather than the posts.

Today, I spoke to an engineer at the local lumber house about laminated beams. He did the calculations and came back with two 1 3/4" x 9 1/2" x 27' lam beams nailed together to replace the 2x10s. Using those lams, he tells me I'd actually only need one 4x4 support in the center. Unfortunately, I don't have easy access to the outside 2x10 because of the soffit and trim board.

That being the case, might it work to replace just the interior 2x10s with a laminated beam, nail the lam beam to the existing outside 2x10s and support the whole business with 4x4 posts at the end and two 4x4 posts in the span 9' from each side wall? I know this might not be the "best" way to do it, but my question is, would it work?

Keep in mind I have no snow load, no second floor, no attic space, just the roof framing above the header.

Any input?
 

Last edited by Star; 09-23-05 at 11:57 AM.
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Old 09-23-05, 11:19 AM
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one other consideration

must be the loads from the roof. If there are any concentrated loads from girders or #1 hipt trusses that sit directly on top of the posts they may produce concentrated loads on the beams if the posts are moved. This may cause the beam to be over stressed.
 
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